Method of operating a UICC and a network node, UICC and network node implementing the method

Abstract

According to an aspect, a method of operating a Universal Integrated Circuit Card, UICC, (56) in a host Mobile Equipment, ME (4) is provided. The method comprises: measuring (1002) one or more characteristics of the host ME (4); determining (1004) whether a characteristic measurement of the host ME (4) coincides with a first ME fingerprint corresponding to the first ME; and performing (1006) a first action if the characteristic measurement of the host ME (4) is inconsistent with the first ME fingerprint.

Description

Technical Field

[0001] The present disclosure relates to a Universal Integrated Circuit Card (UICC) that can exist in a Mobile Equipment (ME), and more particularly, to a method of operating a UICC and a network node in a communication network, and a computer program product implementing the method, and a UICC and a network node. Background Art

[0002] To a consumer, a mobile phone may appear like a single monolithic object, where the subscription, subscriber identity module (SIM), phone, and network act as a cohesive whole with a single purpose. However, there are several different components in the system that play different roles and may sometimes be perceived as working against each other, such as Figure 1 shown. Figure 1 The mobile phone 2 in FIG. 1 is internally logically composed of a mobile equipment (ME) 4 (corresponding to the physical phone) and a SIM 6, which enables the ME 4 to represent a subscriber to a network 8. The phone 2 is the unit that a consumer normally sees and interacts with (usually referred to as a "user equipment" (UE)). The mobile equipment 4 is normally purchased by an end user, but this does not represent a "phone" as understood by the end user (in terms of its intended purpose as a communication device), because the ME 4 can only access a network if a subscription has been provided by a network operator. The ME 4 can access this subscription via the SIM 6. Both the ME 4 and the SIM 6 include respective hardware and software parts, selected components of which are as follows: Figure 1 shown.

[0003] Specifically, to a consumer, the mobile phone 2 and the subscription may appear inseparable, but logically (and almost always physically) they are separate functions. A mobile phone, or more precisely a mobile equipment (ME) 4, is a device that includes a wireless modem 10, a user interface (e.g. including a display, keyboard, touch screen, etc., or none of the above if the mobile phone 2 is an embedded Internet of Things (IoT) device), a power source, etc.

[0004] Typically, the ME 4 comprises a system-on-chip (SoC) module that includes not only a main central processing unit (CPU) 12 on which an operating system (OS) 14 runs, but also modem circuitry 10 for offloading radio network protocol processing, among other things. The modem 10 also typically handles communications with the SIM 6, which in fifth generation (5G) terminology is referred to as a UICC (Universal Integrated Circuit Card). For clarity, Figure 1 A distinction is made between the low-level electrical and logical communication between the modem 10 and the SIM 6 via the UICC PHY 16 (Physical Interface Module).

[0005] Similarly, the SIM 6 includes hardware 18 (as defined in the 3rd Generation Partnership Project (3GPP) TS 31.101 v17.0.0 (2022-03) “UICC Terminal Interface; Physical and Logical Characteristics (Release 17)”), which includes a signaling interface 20 (102 221 PHY) compliant with ETSI TS 102 221 (i.e., compliant with: ETSI TS 102 221 v17.0.0 (2021-10) “Smart Card; UICC Terminal Interface; Physical and Logical Characteristics (Release 17)”) and optionally includes a Universal Serial Bus (USB) interface 22 (inter-chip USB PHY) compliant with ETSI TS 102 600 (i.e., compliant with: ETSI TS 102 600 v10.1.0 (2020-09) “Smart Card; UICC-Terminal Interface; Characteristics of USB Interface (Release 10)”) and a CPU 24. The CPU 24 on the SIM 6 runs a custom operating system provided by the card manufacturer, which is called the card OS 26. The operating system 26 may host multiple applications that run sequentially or simultaneously, but for the purposes of this disclosure, only the Universal Subscriber Identity Module (USIM) application 28 (as defined in 3GPP TS 31.102 v17.4.0 (2021-12) "Characteristics of the Universal Subscriber Identity Module (USIM) Application (Release 17)") is relevant.

[0006] It should be noted that the module that provides subscription information to the ME 4 is generally referred to as a "SIM" 6. As used herein, a SIM refers to the overall capability of providing subscriber information to the phone 2, wherein the physical adaptation of the SIM 6 may be a UICC, an embedded UICC (eUICC), or an integrated UICC (iUICC). The differences between these types of UICCs are described in more detail below, but in most cases, the differences between these types of UICCs at the capability level are not significant. Although these types of UICCs differ significantly in the configuration model used, the configuration of subscriber information to the UICC is not relevant to the present disclosure.

[0007] Mobile devices and subscriptions

[0008] In order for the ME 4 to be able to make all calls except emergency calls, it needs to register itself with a mobile network 8 (either a home network or a visited network). Since the introduction of Global System for Mobile Communications (GSM) communications, the authority to provide the ME 4 with the credentials and information required to register with the network has been separated to the SIM card 6 (UICC), and more recently to embedded (eSIM) (e.g., eUICC) and integrated SIM (iSIM) (e.g., iUICC). The SIM 6 is provided and configured by the home network operator, thereby establishing a trust relationship between the SIM 6 and the operator. The operator controls the contents of the SIM card 6, including any necessary credentials it can use to authenticate itself to the network 8.

[0009] Technically, the SIM card 6 is physically a UICC device (as specified in the above-mentioned ETSI TS 102 221), i.e. a generic smart card. The reason why it is called a smart card (UICC), and specifically the SIM 6, is because it contains and runs the USIM application 28 as specified in the above-mentioned 3GPP TS 31.102 (and many subsequent amendments and extensions). The USIM application 28 has access to authentication credentials provided by the operator, such as its subscriber identifier (International Mobile Subscriber Identity (IMSI)) and a shared key K shared between the SIM 6 and the operator 8.

[0010] Historically, the SIM 6 has been a card, with the first phones using full-sized cards, but due to weight and space usage requirements for the ME, card size has been significantly reduced, and it is now common to use so-called "nano-SIM cards" which are as small as possible while maintaining some degree of physical backward compatibility. A newer approach is to use an eSIM or iSIM that is provisioned over the air (i.e. digitally) without providing a physical SIM card to the customer. These eSIMs and iSIMs either have a separate eUICC discrete chip running the USIM application, as an embedded IP core within the SoC; or as a fully software-based application running in a trusted execution environment (TEE) within the CPU 12 of the ME 4.

[0011] ME and UICC interaction

[0012] The above-mentioned ETSI TS 102 221 defines the interaction between the terminal (ie, ME 4 of the mobile network) and the UICC at the physical layer, the electrical layer, and the logical layer. Figure 2 The different protocol layers in the terminal and the UICC as set out in ETSI TS 102 221 are shown.

[0013] When the SIM 6 is inserted into the ME 4, or when the ME 4 is accessing the UICC after a reset (of the ME 4 or the UICC), the ME 4 will first establish the voltage of the physical layer, as the UICC and the ME 4 may support different power and signaling voltage levels. Subsequently, communication parameters of the data link layer, transport layer and card application toolkit (CAT) layer are further established, after which the ME 4 can establish communication with the USIM application 28, including identifying the capabilities it supports (such as the basic file USIM Service Table (EF TABLE) in the USIM application directory). UST ) documents (as described in the above-mentioned 3GPP TS 31.102). This communication is very complex because the ME 4 needs to support multiple generations of SIM 6 (physical characteristics and electrical characteristics) and USIM applications (third generation (3G) / fourth generation (4G) / fifth generation (5G), as well as various optional features), and the USIM needs to support ME 4 with different capabilities (modem, speed, power saving, etc.).

[0014] Although the UICC protocol is logically a request-response protocol driven entirely by the terminal (ME 4), it has been extended to support active UICC, where the ME 4 periodically polls the UICC to see if the UICC needs to issue commands to the ME 4. This enables the UICC to also initiate commands on the ME side, although the underlying transport protocol is essentially driven only by the ME.

[0015] Identify ME and SIM

[0016] There may be various valid reasons for the ME 4 and SIM 6 to identify each other, such as operator locking (i.e. the ME 4 only works with a SIM 6 from one operator) or phone locking (i.e. the SIM 6 only works for a specific ME 4). This helps the ME 4 to be able to identify itself via the EF in the USIM Application Directory. IMSI (Essential File) Retrieve a subscriber identifier (e.g., IMSI) from the SIM 6 (as described in 3GPP TS 31.102). Accordingly, the USIM application 28 may use the Local Information Active UICC command to retrieve a device identifier (e.g., International Mobile Equipment Identity (IMEI)) as described in 3GPP TS 31.111 v17.2.0 (2021-12) "Universal Subscriber Identity Module (USIM) Application Toolkit (USAT) (Release 17)".

[0017] Both the IMSI and IMEI have the disadvantage of being unauthenticated - the ME 4 lacks a mechanism to determine whether the SIM's IMSI has indeed been configured for that particular card (e.g., a challenge-response protocol using an asymmetric key pair authenticated by the operator that "owns" the IMSI). Similarly, the device's IMEI is provided to the USIM application 28 "as is", and the USIM cannot determine whether the IMEI corresponds to a real physical device, or to a device it is communicating with. For example, a hostile party could perform a relay attack so that either or both of the ME 4 and USIM 28 believe they are communicating with another ME device 4 or SIM 6. Similarly, an attacker with sufficient resources could completely simulate or emulate the SIM 6 or ME 4.

[0018] Standards (e.g. as described in 3GPP TS 42.009v4.1.0 (2006-06) "Technical Specification Group Services and System Aspects; Security Aspects (Release 4)") provide only relatively weak protections, stating: - The IMSI is securely stored within the SIM 6. - The IMEI shall not be changed after the final production process of the ME. It shall be resistant to tampering, i.e. manipulation and alteration, by any means (e.g. physical, electrical and software).

[0019] Typically, the SIM 6 requires the user to enter a personal identification number (PIN) to unlock it, but this is to provide a "knowledge" authentication from the user to the SIM 6. It does not establish or prove to the SIM 6 the validity of the device (such as the IMEI).

[0020] eSIM and iSIM

[0021] While eSIM (eUICC) and iSIM (iUICC) are remotely provisioned and in reality "only" provide digital (profile) information sent from the operator to the device, they share a lot of similarities with the physical UICC. Even the aforementioned 3GPP TS31.101 confirms that the USIM can interact with the ME 4 over non-"SIM form factor" interfaces (as defined in the aforementioned TS 102 221). Figure 3 An example is shown in which a USIM application communicates with a terminal via a non-UICC interface, which is extracted from 3GPP TS 31.101, wherein the non-UICC interface is a USB interface.

[0022] The ME↔eSIM / iSIM interface inherits many legacy features, allowing the migration requirements from the UICC-based SIM interface to the eUICC / iUICC-based eSIM / iSIM to be minimized for ME 4. Therefore, the eSIM / iSIM is accessed using the same UICC-based directory and file structure, uses the same USIM commands, and supports the same active UICC interface as the physical UICC / SIM interface. Therefore, while the physical and electrical characteristics of the eSIM / iSIM may differ from those of the physical SIM, in all relevant parts they are identical to the higher levels.

[0023] Physically Unclonable Function (PUF)

[0024] PUF is used to create a unique response by using implicit or explicit randomness. To create a PUF response, a challenge value is fed to the PUF, which is usually a fixed-length binary string. The response can be used for encryption or device identification purposes.

[0025] The benefit of using a PUF is that two identical PUF implementations on different devices / components can produce different responses when fed the same challenge value. Hence, "unclonable" in a physically unclonable function.

[0026] Implicit randomness is extracted from unpredictable manufacturing variations (e.g. in semiconductor devices) and can be used to create a device-unique response. Explicit randomness, on the other hand, means that additional steps are required to introduce randomness during manufacturing or at a later stage (e.g. at packaging).

[0027] A PUF may consist of one or several sub-functions, each contributing to a part of the PUF response. Examples of sub-functions may be: - Ring oscillator, an odd number of signal inverters in a ring, which uses gate delay propagation as a random source. The response is a comparison between two or more ring oscillators, where the number of oscillations at a given point in time is measured. The result can be, for example, an identifier of the fastest / slowest ring oscillator. - An uninitialized static random access memory (SRAM) memory cell that has two possible states (0 and 1). Before power is applied, the cell is not in any state. At power-up, the cell is stable in one of the two states. The response is the state entered. - Transmission (TX) lines, such as coaxial cables. By using the inherent impedance non-uniformity pattern of any TX line (i.e., the variation of characteristic impedance with distance), the TX line can be identified with high authentication accuracy. The PUF response can be extracted using frequency domain reflectometry (FDR) or time domain reflectometry (TDR) methods. - Radio transmitters, as described in “RF-PUF: Enhancing IoT Security through Authentication of Wireless Nodes using In-situ Machine Learning” (https: / / arxiv.org / abs / 1805.01374), where the radio receiver is able to extract transmitter-specific features from the transmitted signal. Such features include frequency offset, IQ features (amplitude and phase mismatch), and channel features (attenuation, distortion, and Doppler shift).

[0028] The PUF response can be used to create a unique device identity or a device-unique key without having to store the key in, for example, battery-backed RAM (BBRAM) or one-time programmable (OTP) memory. Therefore, it is more difficult for an attacker to steal keys from a device using PUF because the keys are never stored on the device.

[0029] There are several types of PUFs, but they can generally be divided into two different categories, those that support a small number of challenge-response pairs (CRPs) and those with a large number of CRPs. The latter can generate several different responses by using different challenge values ​​as input. The former only allows one or a few challenge values. If the PUF only accepts a single challenge value, this challenge value can be hard-coded or omitted.

[0030] Most PUF types additionally require error correction codes (usually represented as auxiliary data) to function properly, i.e. to improve the probability of recreating the same response given the same challenge value.

[0031] Prior art

[0032] Some existing technologies check the environment that the hardware is operating in. These technologies may include, for example, boot security solutions, which include metric boot, trusted boot, and secure boot.

[0033] Measuring boot involves measuring (e.g., hashing) each component loaded on the system and storing the results in boot registers. Such registers are usually extendable rather than directly writable, e.g., R t+1 =OWF(R t || ArgumentOfExtend). The result can be a hash chain, each individual hash, or a combination of both.

[0034] Trusted boot is essentially a measurement boot, but the values ​​are verified during the boot process. That is, the device itself knows the expected measurement values, and if they are different, the device will not boot or enter a secure state.

[0035] Secure boot requires the use of cryptographic signatures, which must be rooted in a so-called Root of Trust (RoT). This is typically a fused key, which can be unique to each device or a vendor key that is reused by many devices.

[0036] PUFs that use transmission characteristics as a "function" are described in, for example, "Transmission Line Identification via Impedance Inhomogeneity Pattern" (https: / / ieeexplore.ieee.org / abstract / document / 8732652) and "RF-PUF: Enhancing IoT Security through Authentication of Wireless Nodes using In-situ Machine Learning". These solutions describe the use of wired and wireless transmission characteristics to authenticate devices / components, respectively. Wired channel properties include, for example, impedance inhomogeneity patterns, while wireless channel properties include, for example, frequency offsets and phase mismatches.

[0037] US 2021 / 0314365 describes a method for authenticating hardware. The hardware is divided into two layers, where the first layer authenticates the characteristics of the second layer. The characteristics of the second hardware layer are described by firmware, read-only memory, storage memory, fuses, jumpers, soft jumpers, or electronic fuses. Once the second hardware layer is authenticated, it can be used to authenticate the software layer. Summary of the invention

[0038] The overall security posture of mobile communications has improved over time. For example, 5G has improved the security and privacy of ME authentication to the network, and the over-the-air (OTA) remote provisioning of eSIM / iSIM is also secure and resistant to tampering by third parties and middlemen.

[0039] While the ME↔USIM interface has been extended to support new features on advanced networks, the basic assumption has not changed, that is, both the ME and the USIM assume that the other is trustworthy and that no entity can insert itself between the two. This may be a valid assumption for threat models that target the unit as a whole (i.e., the ME and SIM are inseparable).

[0040] However, there has been an increase in the use of mobile subscriptions for other purposes, such as using the subscription as an identifier (in WhatsApp, Telegram and other services, the user's entire online identity is tied to the subscriber's phone number (although it should be noted that the phone number is not directly related to the SIM card's IMSI, for most purposes it can be assumed that the two are temporarily equivalent)). Another use of mobile subscriptions is the ability for users to receive Short Message Service (SMS) messages (i.e., that they can be contacted via their subscription) as a form of multi-factor authentication (MFA). Against these kinds of attacks, the assumption that a SIM cannot be surreptitiously removed and inserted into another device is no longer a safe assumption.

[0041] This also exposes the problem of lack of ME↔USIM authentication, where a USIM application cannot securely detect that it has been swapped to another device (assuming an adversary is able to forge the IMEI) since there is no authentication mechanism to securely bind any available device identifier to any unique device.

[0042] Some examples of where lack of authentication between the ME and the UICC could cause harm include: - If, for example, autonomously operating IoT devices (such as temperature sensors) are deployed in a forest. An attacker could remove the SIM card from the IoT device and use it in his own device to make phone calls (potentially high-priced ones), use data services, etc. The attacker would not have to pay for the services used, as the bill would go to the subscription / subscriber, i.e. the SIM card owner. It could take days to notice this situation, as a service person might need to visit the location of the IoT device to notice the problem, and sending someone to the site might not be considered a high priority, giving the attacker more time to use the services and run up the bill.

[0043] Conventional methods of locking a SIM card to a phone's IMEI are ineffective because it is assumed that a hostile party would be able to clone the IMEI. - If the owner of the SIM card is utilizing Applied Authentication and Key Management (AKMA) or Generic Bootstrapping Architecture (GBA)-based authentication to access network services, an attacker can swap the SIM card onto their own device, access such services in the victim's name, and then swap it back without the victim noticing. This of course requires the attacker to have access to the phone. However, without access to the victim's biometrics (which is one of the default phone access authentication mechanisms today), the attacker cannot unlock the victim's phone, and guessing the SIM PIN as 1234 or 0000 may produce good results.

[0044] Again, IMEI locks are ineffective against this method. SIM PINs do offer some protection, but only for users who actively use it. It is thought that more and more users are relying on biometrics and either disabling PIN checks or using defaults.

[0045] US 2021 / 0314365 cited above describes a solution for using transmission characteristics to identify components / devices. Although they show the feasibility of using this property to identify changes, they are not directly applicable to the UICC-ME scenario.

[0046] None of the above boot solutions are intended to authenticate hardware. Although US 2021 / 0314365 describes a solution for authenticating hardware, it is built based on a description of the hardware, not on a communication channel.

[0047] Certain aspects of the present disclosure and embodiments thereof may provide solutions to these or other challenges. Specifically, the physical UICC chip and the USIM application running thereon may perform measurements of the ME, including both: low-level parameters (e.g., voltage and communication parameters, signal levels, and duty cycle lengths); and high-level measurements (e.g., the order of access to directories and files on the UICC main directory and / or the USIM application directory, the order of USIM commands and their parameters, and their timing information). These measurements may be input into a monitoring component, which will first use these measurements to determine the fingerprint of the ME, and then detect whether the fingerprint has changed from the established baseline, thereby allowing the USIM application to react to the ME change, such as stopping its operation or sending a signal about the suspicious behavior to the home public land mobile network (HPLMN). That is, the monitoring component may determine the fingerprint of the ME based on these measurements, and may compare subsequent measurements with the fingerprint to determine whether the ME has changed.

[0048] The above aspects provide fingerprint recognition and ME replacement detection from within the UICC / USIM without requiring changes to the UICC / USIM↔ME protocol, allowing the solution to be deployed without requiring changes to the ME. The solution will detect both replacement of the ME (i.e., placing the UICC / USIM into a different ME) and hardware (HW) modifications to the ME (which may generally indicate an attack on the ME).

[0049] The aspects and / or embodiments described herein may provide one or more of the following technical advantages. Specifically, the proposed solution does not require any changes to the ME or its interface with the UICC / USIM. It does not rely on the ME IMEI, which may be forged. The solution is invisible to the ME, i.e., a hostile party will not be able to identify whether the SIM supports fingerprint recognition by passive observation alone. Locking the SIM to a known ME makes it more difficult to remove the SIM from the device and set it in a hostile environment to implement further attacks (e.g., voltage and clock interference, etc.). The solution has the potential to be used to detect malicious changes to the device, such as attaching or welding measurement probes (impedance changes) and other hardware tampering. The solution can be deployed gradually by operators (i.e., one SIM at a time) and can be deployed selectively, i.e., only for customers who require or need higher security.

[0050] According to a first specific aspect of the technology described herein, a method for operating a universal integrated circuit card UICC in a host mobile device ME is provided, the method comprising: measuring one or more characteristics of the host ME; determining whether the characteristic measurement value of the host ME is consistent with a first ME fingerprint corresponding to a first ME; and if the characteristic measurement value of the host ME is inconsistent with the first ME fingerprint, performing a first action.

[0051] According to a second aspect, there is provided a method of operating a universal integrated circuit card UICC in a first mobile equipment ME, the method comprising: measuring one or more characteristics of the first ME; and determining a first ME fingerprint of the first ME based on the characteristic measurements.

[0052] According to a third aspect, a method for operating one or more network nodes in a network is provided, the method comprising: receiving a first message from a host mobile device ME that is registering and / or authenticating with the network or has been registered and / or authenticated with the network; processing the first message to extract an indication of whether a universal integrated circuit card UICC in the host ME believes that a characteristic measurement value of the host ME is consistent with a first ME fingerprint corresponding to the first ME; and performing an action based on the extracted indication.

[0053] According to a fourth aspect, there is provided a computer program product comprising a computer-readable medium having a computer-readable code embodied therein, the computer-readable code being configured so that: when executed by a suitable computer or processor, the computer or processor executes a method according to the first aspect, the second aspect, the third aspect or any embodiment thereof.

[0054] According to a fifth aspect, a universal integrated circuit card UICC for a host mobile equipment ME is provided, and the UICC is configured to: measure one or more characteristics of the host ME; determine whether the characteristic measurement value of the host ME is consistent with a first ME fingerprint corresponding to the first ME; and if the characteristic measurement value of the host ME is inconsistent with the first ME fingerprint, perform a first action.

[0055] According to a sixth aspect, a universal integrated circuit card UICC for a first mobile equipment ME is provided, the UICC being configured to: measure one or more characteristics of the first ME; and determine a first ME fingerprint of the first ME according to the characteristic measurement values.

[0056] According to a seventh aspect, one or more network nodes for a network are provided, the one or more network nodes being configured to: receive a first message from a host mobile device ME that is registering and / or authenticating with the network or has been registered and / or authenticated with the network; process the first message to extract an indication of whether a universal integrated circuit card UICC in the host ME believes that a characteristic measurement value of the host ME is consistent with a first ME fingerprint corresponding to the first ME; and perform an action based on the extracted indication.

[0057] According to an eighth aspect, a universal integrated circuit card UICC for a mobile equipment ME is provided, the UICC comprising: a control unit configured to control the operation of the UICC; an interface circuit coupled to the control unit, wherein the interface circuit is configured to be connected to a corresponding interface circuit in the ME so as to enable exchange of electrical signals with the ME; and one or more probe assemblies coupled to the interface circuit and configured to measure characteristics of the electrical signals received from the ME via the interface circuit.

[0058] According to a ninth aspect, a universal integrated circuit card UICC for a host mobile equipment ME is provided, wherein the UICC comprises a processor and a memory, the memory containing instructions executable by the processor, so that the UICC is operable to: measure one or more characteristics of the host ME; determine whether the characteristic measurement value of the host ME is consistent with a first ME fingerprint corresponding to a first ME; and if the characteristic measurement value of the host ME is inconsistent with the first ME fingerprint, perform a first action.

[0059] According to a tenth aspect, a universal integrated circuit card UICC for a first mobile equipment ME is provided, wherein the UICC comprises a processor and a memory, the memory containing instructions executable by the processor, whereby the UICC is operable to: measure one or more characteristics of the first ME; and determine a first ME fingerprint of the first ME based on the characteristic measurement values.

[0060] According to an eleventh aspect, one or more network nodes for a network are provided, wherein the one or more network nodes include a processor and a memory, the memory containing instructions executable by the processor, whereby the one or more network nodes are operable to: receive a first message from a host mobile device ME that is registering and / or authenticating with the network or has been registered and / or authenticated with the network; process the first message to extract an indication of whether a universal integrated circuit card UICC in the host ME believes that a characteristic measurement value of the host ME is consistent with a first ME fingerprint corresponding to the first ME; and perform an action based on the extracted indication.

[0061] According to a twelfth aspect, a universal integrated circuit card UICC for a mobile equipment ME is provided, the UICC comprising: a control unit operable to control the operation of the UICC; an interface circuit coupled to the control unit, wherein the interface circuit is operable to be connected to a corresponding interface circuit in the ME so as to enable exchange of electrical signals with the ME; and one or more probe assemblies coupled to the interface circuit and operable to measure characteristics of the electrical signals received from the ME via the interface circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Some embodiments contemplated herein will now be described more fully with reference to the accompanying drawings, in which:

[0063] Figure 1 is a simplified schematic diagram of a conventional mobile device and SIM;

[0064] Figure 2 The different protocol layers in the terminal and the UICC are shown;

[0065] Figure 3 shows a USIM application communicating with a terminal via a non-UICC interface;

[0066] Figure 4 is a simplified schematic diagram of a conventional mobile device and SIM according to various embodiments;

[0067] Figure 5 is a state transition model representing the operation of the monitoring component in the UICC;

[0068] Figure 6 is a signaling diagram showing communication establishment between UICC and ME and USIM activation;

[0069] Figure 7 is an example of a single character sent over an input / output line;

[0070] Figure 8 is a signaling diagram illustrating the use of fingerprinting techniques to allow or prevent network authentication according to some embodiments;

[0071] Fig. 9 is a signaling diagram illustrating the use of SUCI to communicate a non-matching output of a fingerprinting technique according to some embodiments;

[0072] Fig.10 is a flow chart illustrating a method of operating a UICC according to some embodiments;

[0073] Fig.11 is a flow chart illustrating another method of operating a UICC according to some embodiments;

[0074] Fig.12 is a flow chart illustrating a method of operating one or more network nodes according to some embodiments; and

[0075] Fig.13 A network node according to some embodiments is shown. DETAILED DESCRIPTION

[0076] Some embodiments contemplated herein will now be described more fully with reference to the accompanying drawings.The embodiments are provided merely as examples to convey the scope of the subject matter to those skilled in the art.

[0077] As described above, the subscriber identity modules (SIMs) in the mobile equipment (ME) and the UE are different from each other. The SIM is an example of a universal integrated circuit card (UICC) and may be physically implemented as a UICC (e.g., in the form of a conventional SIM card), an embedded UICC (eUICC), or an integrated UICC (iUICC, e.g., where the UICC is a core integrated into a system on chip (SoC)).

[0078] Figure 4 Shown are a conventional ME and an exemplary UICC (in the form of a SIM) that can be used to implement the techniques described herein. Figure 4 and Figure 1 Similarly, and common components and features of the ME 4 and the SIM are given the same reference numerals. Thus, the SIM 56 comprises hardware 58 which may include a conventional ETSI TS 102 221 compliant signalling interface 20 (102 221 PHY) and optionally a conventional ETSI TS 102 600 compliant USB interface 22 (inter-chip USB PHY) and a CPU 24.

[0079] The CPU 24 on the SIM 56 runs a custom operating system provided by the card manufacturer, which is referred to as the card OS 26. The operating system 26 may host multiple applications that run sequentially or simultaneously.

[0080] In order to enable the SIM 56 to "fingerprint" the ME 4, the SIM 56 includes one or more probes that can be used to measure characteristics of the ME 4. In some embodiments, the SIM hardware 58 may include a physical layer probe component 60 that can measure the characteristics of any electrical signal received from the ME 4. In some embodiments, the SIM software 62 includes a first behavioral probe 64 that can be used to measure or monitor characteristics related to the activity or operation of the USIM application 28. In some embodiments, the SIM software 62 includes a second behavioral probe 66 that can be used to measure or monitor characteristics related to the activity or operation of the card OS 26. The SIM software 62 may also include a monitoring component 68 that can collect or receive measurements of characteristics from one or more probes 60, 64, 66, and implement the fingerprinting techniques described herein (e.g., techniques including deriving or determining the fingerprint of the ME 4 and / or techniques for comparing the characteristics of the ME 4 with the fingerprint of the ME).

[0081] It should be understood that although Figure 4 The SIM 56 is shown to include a number of different probes 60 , 64 , 66 , but the functionality of two or more of these probes may be combined into a single entity or component.

[0082] The additional functionality provided in SIM 56 generally involves two distinct steps: (i) monitor 68 performs fingerprint recognition and matching of stored fingerprints, and (ii) SIM (UICC) 56 reacts to the (positive or negative) fingerprint match result.

[0083] These steps are described in more detail below.While these steps and much of this disclosure are described for a physically discrete, removable UICC in the form of a SIM card, it will be appreciated that these techniques may be readily adapted to other forms of UICC, such as eUICCs and iUICCs.

[0084] The operation of monitoring component 68 may be represented by a state transition model. Figure 5 An exemplary state transition model of the monitoring component 68 (i.e., the portion of the UICC that performs fingerprint recognition and stored fingerprint matching) is shown in FIG. It should be understood that the monitoring component 68 may follow the same state transition model as Figure 5 The state transition model shown may be different from an alternative state transition model (e.g., an alternative state transition model that follows a different sequence of events). The monitoring component 68 may persistently store information about whether it is disabled (i.e., the fingerprint generation / detection algorithm is deactivated), whether it is learning a fingerprint (also known as "enrolment"), or whether a fingerprint has already been learned.

[0085] If the operation of the monitoring component 68 is disabled, it will not perform any operation. Otherwise, the monitoring component 68 will start collecting measurements of the ME that is carrying the UICC (i.e., the ME in which the UICC is present). The measurements may be collected from any one or more of the UICC PHY 20 / 22, the card OS 26, and the USIM application 28. The monitoring component 68 may need to collect measurements for a period of time until it determines that it has sufficient data to store the learned fingerprint or compare the measured fingerprint with the stored fingerprint (or compare the measured value with the stored fingerprint) to determine whether the measured fingerprint / measurement value is consistent with the stored fingerprint. In the latter case, the result can be: either match the stored fingerprint (i.e., consistent), or do not match (i.e., inconsistent).

[0086] When a new SIM 56 is provided, it will enter a registration phase either initially or after an explicit enabling operation. During this phase, the monitoring component 68 receives measurements from one or more probes 60, 64, 66 in the SIM 56 and uses these measurements to create a fingerprint of the ME 4. This fingerprint can be a mean and / or expected variance, an explicit threshold of the measurement, or a machine learning (ML) model trained on the measurement, or includes a mean and / or expected variance, an explicit threshold of the measurement, or a machine learning (ML) model trained on the measurement. It can also be a combination of two or more of these items.

[0087] Additionally or alternatively, monitoring component 68 may receive a configuration from a SIM provider, a home network operator (at least it may be provided by it), or an end user of SIM 56. The configuration may specify what is considered a match / no match, for example, a time limit for how long a threshold must be exceeded before action is taken, how many measurements need to exceed a threshold at a certain point in time. The configuration may also specify how often the monitor should evaluate the measurements.

[0088] The monitoring component 68 may also be reset, in which case it will either be disabled, or re-enter the registration phase. This may be controlled by the USIM application 28.

[0089] During the monitoring phase, the monitoring component 68 can use the fingerprint and the configuration. If the measurements received from the probes 60, 64, 66 fall outside the fingerprint, and the configuration deems the measurements to be abnormal enough to be classified as a mismatch (e.g., an attack on the security of the UE), the monitoring component 68 can send a signal about the situation to the USIM application 28, which can then take action (if appropriate). Alternatively or additionally, the monitoring component 68 can provide the detected measurement abnormality or an indication of the existence of the abnormality to the home network of the SIM 56 (e.g., the home public land mobile network (HPLMN)). This is further described below.

[0090] In some embodiments, the fingerprint match may be one-shot, i.e., once a decision has been made, the only way to change the decision is to either reset the learned fingerprint, or to restart the ME 4 (which will restart the fingerprint recognition and matching process). Alternatively, the monitoring component 68 function may continue to accumulate more measurements and continually re-evaluate the fingerprint match. This may, for example, detect a "hot swap" of a SIM 56, where the SIM 56 is first connected to a real ME and then switched to be controlled by another ME without interrupting power or clock signals.

[0091] Figure 6 The sequence diagram in provides an abstract (i.e., omitting some technical details) view of how the SIM 56 is initialized (i.e., early UICC initialization and USIM setup). The signals sent to the monitor 68 come from the probes 60, 64, 66. Some details are abstracted, for example, active UICC issuance is more complex at the protocol level.

[0092] The first step is for the ME 4 to provide power and clock signals to the SIM card 56, which will perform low-level initialization and respond with ATR (Answer to Reset) data. The ME 4 uses the ATR response to potentially change the supply voltage and other logical characteristics (powering down the SIM 56 and restarting it with the new electrical parameters). Once the low-level electrical parameters have been agreed, the ME 4 will retrieve various Elementary Files (EFs) from the UICC file system, allowing it to identify the device (e.g., EF Integrated Circuit Card Identifier (EF Identifier)). ICCID )) and its supporting applications (EF DIR ). Since a single UICC 56 can support multiple different applications, the ME 4 can use this process to determine whether the SIM card 56 provides a version of the USIM application 28 that can communicate with it. Once the USIM application 28 has been identified, the ME 4 will issue a "SELECT" command to activate the USIM application 28.

[0093] In addition, once the USIM application 28 is activated, the ME 4 will read various files provided by the application 28 that can be read before authentication (referred to as "always allowed" files). These files help the ME 4 determine the exact capabilities of the USIM application 28, the types of networks it supports, the preferred network to join, the interface language, etc. The USIM application 28 can also issue active UICC commands to retrieve information from the ME 4. At the protocol level, the UICC does not "issue" UICC commands - instead, the ME 4 must send a request to the UICC 56 to retrieve active commands. The UICC 56 can indicate at any time that it wants to issue active commands by indicating in the SW2 status word of any reply it sends (for any request from the ME 4) that it wants to issue active commands. However, from the application's perspective, it will only issue active commands, and the transport layer will handle setting SW2 and waiting for the "ME Get" command.

[0094] During the above process, the UICC PHY probe 60, OS probe 66 and USIM application probe 64 will provide the monitoring component 68 with the measured values ​​of the relevant characteristics. The types of these measured values ​​vary depending on the probe type. For example, the PHY probe 60 provides low-level characteristics such as voltage information, signal conversion edge accuracy and slope. The card OS 26 can provide information that occurs outside the control of the USIM application 28 (such as the order of file retrieval and the timing between them) and the USIM information disclosed in the USIM protocol command, as well as any additional information that it can retrieve using active UICC commands. Although the data can be fingerprint characteristics, the low-level physical characteristics (caused by impedance changes in the interface components) and the behavioral differences (between the CPU 12 in the ME 4 and the phone OS 14 implementation) are more important because they are more difficult to copy than pure data.

[0095] There are various characteristics that can be measured by the UICC PHY probe 60, the card OS probe 66, and the USIM application probe 64. Some of these characteristics may vary based on the physical characteristics of individual discrete components (chips, capacitors, resistors, inductors, transmission lines, and contacts), which vary due to software differences between devices and versions, and high-level responses such as IMEI values. These characteristics vary in the effort required to be perfectly replicated by an adversary, from extremely difficult (electrical characteristics) to potentially quite simple (OS-level data).

[0096] Electrical Characteristics ETSI TS 102 221 v17.0.0 defines the UICC electrical specification and allows the supply voltage (VCC) to vary within the following four discrete levels:

[0097] Class A: 4.5V to 5.5V

[0098] Class B: 2.7V to 3.3V

[0099] Class C: 1.62V to 1.98V

[0100] Class D: 1.1V to 1.3V.

[0101] The final choice of supply voltage can be varied in many ways. For example:

[0102] 1. The SIM 56 may indicate (in the ATR response) that it supports a voltage level lower than the initial cold reset voltage, thereby allowing the ME 4 to reduce the operating voltage - the operating voltages supported by different ME 4 may be different, so for example, if the SIM 56 indicates that it supports all voltage classes, one ME 4 may support all voltage classes and start at class A and then change to class D, while another ME 4 may only support classes A and C. It can be assumed that the ME 4 selects the lowest possible voltage level supported by the SIM 56 to reduce power consumption.

[0103] 2. The average voltage for a class can be different for different MEs. Voltage regulators (converters) may have physical manufacturing differences within manufacturing tolerances. That is, although two MEs 4 have the same brand and model of voltage regulator, one ME 4 may provide a Class 1 voltage of 5.00 V, while another ME may provide a Class 1 voltage of 4.98 V.

[0104] 3. Ripple (i.e., deviation from the average voltage level) can be different for different MEs. Two devices with the same average VCC = 5.00 V can still differ in their measurable ripple (noise), being ±0.01 V for one device and ±0.05 V for another.

[0105] 4. The behavior of average VCC and ripple may also differ based on current (drawn by the SIM 56) and temperature. During initial startup (low current draw), VCC may be 5.00 V, but during later stages, when the USIM 56 is performing cryptographic calculations (high current), it may drop to 4.95 V.

[0106] That is, even for a simple supply voltage VCC, measurable differences can already occur, which exist (absolutely) not only between different ME models, but also between two MEs of the same brand.

[0107] It should be noted that even the voltage switching after ATR is measurable: for example, the time required for different MEs to switch from one voltage to another may be different. This would require the SIM 56 to be able to measure the time difference between two VCC high levels by relying only on (a small amount of) capacitor stored energy and a low-power independent timer.

[0108] All of these electrical characteristics vary based on the ME supplier's choice of voltage regulation, bypass and filtering capacitors, and also based on individual differences in the characteristics of the actual samples used in manufacturing.

[0109] Clock Characteristics - The ME 4 provides an external clock signal to be used in the UICC protocol to the SIM 56. The electrical characteristics of the clock are defined in Table 5.3 of ETSI TS 102 221 v17.0.0, which is shown below: Table 5.3 of ETSI TS 102 221 v17.0.0

[0110] Table 5.3 shows that the high voltage can vary significantly, for example, for Class C devices, VOH = [1.13, 1.98] V. The clock frequency f = [1, 5] MHz and the duty cycle are between 40% and 60%, with a wide possible variance that can be measured. Therefore, there are several measurable characteristics of the clock signal: frequency, high and low voltage levels, and duty cycle. In addition, since the clock signal is a periodic transition signal, it also has other measurable properties. For example, while the frequency itself may be stable, there may be clock signal dispersion, that is, deviations from the expected clock edge location. The clock driver is also limited by the transition slope, which affects the rise time and fall time of the signal (which may also be affected by various filtering capacitors). In addition, no digital signal can completely avoid overshoot and undershoot, and the settling time of the signal due to ringing may also vary from device to device.

[0111] Logical characteristics ——The actual data content of ME↔SIM communication is also transmitted through physical contacts, where the input / output (I / O) signals have specific electrical requirements. Table 5.4 below shows the electrical tolerances of UICC I / O signals for Class A operation mode: Table 5.4 in ETSI TS 102 221 v17.0.0

[0112] Furthermore, because the signal line varies between low and high values, it can contain measurable device-to-device differences in signal rise and fall rates, overshoot and undershoot voltages, and settling times, as described above with respect to clock signals.

[0113] Data link protocol characteristics ——The data link protocol defines how individual characters are encoded and sent over the I / O lines. Figure 7 An example of a single character sent over an I / O line is shown in FIG. 1 , which corresponds to ETSI TS 102 221 v17.0.0. Figure 7 .2.

[0114] The logic signal electrical characteristics are described above, and the data link protocol also allows for the accuracy of measuring character durations (e.g. if one device uses 10.05 time units and another uses 9.90 time units for a single character, both are within nominal tolerance) and guard times. The devices may also have current and temperature coefficients, and inherent deviations, for example (some devices may have "noisy" guard times with large deviations from the mean).

[0115] The transport layer also has concepts of blocks, chains, error detection, resynchronization, etc., all of which can be potential sources of behavioral differences between devices.

[0116] Transport protocol characteristics -- The transport layer relies on the data link layer to send bytes and blocks over the I / O lines. It focuses on the application protocol data unit (APDU) and its transmission. This is described in section 7.3 of ETSI TS 102 221 v17.0.0 and allows for some variation and decision space in how the APDU is encoded and how it is transmitted over the data link protocol. These choices can reflect differences in the lower layer implementation of the transport protocol driver.

[0117] Application Selection Protocol Features Once the ME↔SIM handshake and transport protocol have been established, the ME 4 will typically read several files from the Master File (MF) records that the SIM 56 defaults to after reset. As described in 3GPP 31.101 v17.0.0, 3GPP requires that EF ICCID EF DIR ,DI,EF ARR and EF UMPC The following characteristics may differ in how the ME accesses these files: which files are accessed (the ME may not read all files), the order in which the files are accessed, and the time difference between these accesses.

[0118] At some point in time, it may be reading EFDIR After detecting the presence of the USIM application 28 on the SIM 56, the ME 4 will issue a "select assist" command, which instructs the card to start the USIM application 28. Whether the card OS 26 actually starts the USIM application 28 only at this point in time, or whether the USIM application 28 is already running and will receive the "you are selected" signal from the card OS 26 is an implementation detail of the card 56 itself and is not visible to the ME 4.

[0119] It should be noted that at this level, most of the differences are due to firmware and OS differences, not to inherent electrical and manufacturing differences between two devices of the same brand. Therefore, the USIM 56 and proactive UICC commands are more useful in differentiating between replacements of two devices of different makes and models (different manufacturers), or in some cases, between two devices of the same type with different firmware and OS versions. In extreme cases, it may be possible to detect a ROORed phone if the ROOR operation has an effect on the phone OS load or kernel driver parameters.

[0120] USIM application protocol characteristics - The USIM application protocol (as described in 3GPP TS 31.102 v17.4.0) is very complex. Once a USIM application 28 is selected, there may be significant differences between different devices based on any of the following: which commands the ME 4 issues (such as file reads; section 4.2 of 3GPP TS 31.102 v17.4.0 defines 51 EFs as part of the USIM application directory), in what order, which parameters are used (if applicable), and the time interval between individual commands.

[0121] Active UICC Information Features - The USIM 56 can also issue commands to the ME 4 using the active UICC. This interface is referred to as the USIM Application Toolkit (USAT) in 3GPP TS 31.111 v17.2.0 (2021-12) "Universal Subscriber Identity Module (USIM) Application Toolkit (USAT) (Release 17)". The USAT defines 44 commands that can be issued to the ME. However, many of these commands are not often used by the SIM, or have side effects (such as having user-visible effects), which means that they cannot be used invisibly by the USIM.

[0122] Some of the proactive UICC commands include "Polling Interval", "Timer Management", "Run on Command", "Service Search", Geolocation Request, and "Provide Local Information" (this list is not exhaustive). While it can be assumed that an attacker (i.e., a party that is trying to get the SIM 56 to leak sensitive information) is able to forge any returned data (such as forging the IMEI via "Provide Local Information"), a careless attacker could return these values ​​without taking into account the processing time required on the real (original) ME, allowing the time taken by the ME to process the proactive command to be used as a measurement. Consider, for example, a ME where the IMEI is derived from a hardware identifier for each request, and a careless attacker could hardcode the result into a protocol simulator, returning the result faster than the original device.

[0123] Inter-chip USB protocol characteristics -- ETSI TS 102 600 v10.1.0 (2020-09) Smart Card; UICC Terminal Interface; Characteristics of the USB Interface (Release 10) defines the USB protocol implemented over the physical SIM chip contacts, which can be considered as a high-performance connection to the UICC capabilities. The USB protocol itself is a host-driven protocol, just like the core UICC protocol (described in ETSI TS 102 221 v17.0.0), where the host sends requests to the device and the device replies. However, unlike the historical UICC protocol (which has been replaced by USB), USB is much more flexible. In theory, the SIM 56 can represent multiple devices through the USB protocol, including keyboards and network interface cards. In practice, the host ME 4 is likely to severely limit the USB device capabilities in the SIM device. However, this does not prevent the USB protocol (including its electrical parameters and signaling parameters) from providing a useful source of measurements for fingerprinting the ME 4. The timing between USB commands, the order in which commands are issued, etc., can also be measured. In some embodiments, the UICC may emulate various types of USB devices and detect differences in the behavior of the ME towards these USB devices, where some may choose to activate some types of USB devices while others may ignore them.

[0124] As described above, monitoring component 68 may perform fingerprint generation and subsequently fingerprint matching to determine whether UICC 56 exists in the same ME 4; or whether ME 4 has been tampered with since the fingerprint was generated; or whether the software / firmware of ME 4 has been updated or altered since the fingerprint was generated.

[0125] Because techniques for generating fingerprints from a set of measurements are well known in the art, this disclosure does not provide extensive details regarding the generation, storage, or matching of fingerprints. For example, some techniques for generating fingerprints based on a set of measurements derived from different types of measurement sources, including physical measurement sources and measurement sources related to higher protocols, are described in the following literature: "Identifying unique devices through wireless fingerprinting" by Loh Chin Choong Desmond et al., WiSec '08: Proceedings of the first ACM conference on Wireless network security, March 2008, pp. 46-55; "Network Protocol System Fingerprinting - A Formal Approach" by Guo Qiang Shu and David Lee; "Passive os fingerprinting methods in the jungle of wireless networks" by Martin Lastovicka et al., NOMS 2018-2018 IEEE / IFIP Network Operations and Management Symposium, 2018, pp. 1-9; and "IoT Device Fingerprint using Deep Learning" by S. Aneja, N. Aneja, and M.S. I. Slam, 2018 IEEE International Conference on Internet of Things and Intelligence System (IOTAIS), 2018, pp.174-179. In general, there are various approaches that can be taken, two of which are briefly described. The first option is relatively simple and lightweight, while the second option is significantly more expensive to implement (in terms of processing resources). The first option utilizes statistical correlation techniques, while the second option utilizes artificial intelligence (AI) or machine learning (ML) models.

[0126] In statistically relevant examples, fingerprinting will identify through statistical analysis those measurements of characteristics that are both sufficiently stable (variance is not too high) and known to vary for different equipment (MEs). The stored fingerprints may consist of mean and / or variance information for the selected characteristics, and matching may compare the current measurement to the fingerprint using threshold matching (e.g., using M-choose-N match-to-no-match selection) or using a more complex fuzzy matching algorithm (e.g., where an error correction algorithm is used that allows a predefined degree of error in the measurement). The algorithm may also be configured to allow different measurements to have different error tolerances.

[0127] Due to inherent processing limitations in such a component, it would be unlikely to train a complete AI / ML model in the SIM 56. However, the model could be partially trained offline (i.e., separate from the SIM 56) using various measurements from the actual selected MEs. When the SIM 56 applies the measurements of a particular ME to the model, the output weights of the model can be recorded as the fingerprint of the ME 4. Another approach would be to use transfer learning to adapt a previously trained generic model to a three-element classifier tailored to the specific fingerprinted ME (e.g., more data / match / no match).

[0128] In some embodiments, the generation of fingerprints and / or the evaluation of stored fingerprints may be enhanced using information stored in templates for a particular model of ME. Specifically, while the UICC 56 may measure and learn the typical behavior and characteristics of the ME 4 from scratch, it may be useful for the UICC 56 to have a template available for a particular model of ME (or ME from a particular manufacturer) that indicates which characteristics should be measured and / or what range these values ​​should be within. Alternatively, the template may be an ML model to be fine-tuned for a particular ME 4. During the fingerprint identification / enrollment phase, these values ​​may be adjusted so that they are applicable to the ME 4 being evaluated. These templates may be based on manufacturer measurements and estimates, but may also be generated and updated based on an active UICC that is capable of reporting the generated fingerprint to the network 8.

[0129] The following section describes the detection and reaction to fingerprint mismatches in the USIM application 28. In some embodiments, the monitoring component 68 described above may only make a decision on the match (i.e., consistency) of the current measurement value with the stored ME fingerprint. The action taken after reaching a consistency decision (match or mismatch) can be determined by the USIM application 28 and any security policies configured. For the UICC 56, the goal is to prevent undesirable changes to the operating environment. Such changes may be, for example, that the UICC has been moved to another ME, that electrical detection or switching circuits have been added between the UICC and the ME, or physical changes to the ME itself.

[0130] Whatever the exact attack vector, what the UICC 56 is protected from adversaries is its contents, specifically the authentication credentials required by the ME 4 to authenticate itself to the network 8. These credentials are used (but not leaked) during the network registration phase. Therefore, the natural decision point is when the ME 4 requests the UICC 56 to perform network authentication. The actions of the UICC are described below assuming that the fingerprint match / no match decision of the monitoring component is used during the network authentication step, although in practice, the making and use of this decision may occur earlier and / or later during the ME-UICC interaction.

[0131] Figure 8 Signaling involving the use of fingerprinting techniques to allow or prevent network authentication is shown in accordance with some embodiments. Figure 8 The signaling between the components of the UICC 56, ME 4 and the network 8 is shown. Thus, the ME 4 initiates authentication with the network 8 (which is ultimately handled by the authentication server function (AUSF) of the home network, but for Figure 8 For the purposes of this specification, it is sufficient to note that ME 4 accesses network 8). ME 4 receives RAND and AUTN parameters from network 8 as part of an authentication request.

[0132] To obtain the session keys, the ME 4 will issue an AUTHENTICATE request to the USIM application 28 (as described in the above-mentioned 3GPP TS 31.102), which will authenticate RAND and AUTN using the long-term key K (shared with the home mobile network operator (MNO)) and, if successful, will derive the CK and IK key materials and return them (along with the authentication response RES) to the ME 4. The ME 4 can then derive the session keys (KAUSF, KgNB, etc.) using the CK and IK and initiate encrypted communications with the network 8.

[0133] According to an embodiment of the disclosed technology, the USIM application 28 may query the monitoring component 68 to check whether the ME 4 behavior (represented by the characteristic measurement value) is consistent (match) or inconsistent (mismatch) with the stored fingerprint, rather than immediately returning the CK and IK parameters. If it is a match, the USIM application 28 continues to return the CK and IK to the ME 4 as usual. If a "mismatch" situation is detected, it may instead return an error to the ME 4, or not respond to the ME 4 at all. This will prevent the ME 4 from completing registration with the network 8, because the ME 4 will not be able to calculate the correct key material.

[0134] It should be noted that the query may alternatively be a local flag within the USIM application 28 based on an asynchronous notification from the monitoring component 68 that is sent by the monitoring component 68 after it has made a decision. Figure 8The synchronous polling method is shown in FIG.

[0135] As mentioned, described here is one potential decision point for the techniques described herein, namely a point in the ME↔ network protocol where the UICC 56 can make an influential decision. This decision point and other decision points are further described below. In addition, one potential action for a "mismatch" situation has been described. Additional / alternative actions are also described below and include actions that affect only the UICC 56 and ME 4 as well as additional actions with the HPLMN 8.

[0136] Decision Points - As used herein, a "decision point" is a moment in the ME↔UICC interaction / protocol at which the UICC 56 may choose to deviate from "normal" behavior in a way that has a significant impact on the ability of the ME or an attacker to take further action with the UICC 56.

[0137] "Authentication": As mentioned previously, the "Authentication" decision point occurs during the registration of the ME 4 with the network 8. As part of the registration reply, the network 8 provides the RAND and AUTN parameters to the ME 4. In order to derive the network session key material, the ME 4 requires the CK and IK parameters, which requires access to the long-term authentication key K, which only the USIM application 28 has access to.

[0138] Therefore, a successful network registration process requires cooperation from the UICC 56 / USIM application 28. This allows the UICC 56 to deny the ME 4 access to the network 8 if the monitoring component detects a "mismatch" condition.

[0139] PIN: If a "no match" result can be reliably determined prior to the authentication process (e.g., before the ME 4 uses a VERIFYPIN command to verify the user PIN of the UICC), then the "no match" result can be used to prevent further use of the UICC 56. In such an instance, the UICC 56 / USIM application 28 may reject any / all PIN codes entered into the ME 4 for unlocking the UICC 56, even if the user of the ME 4 enters the correct PIN.

[0140] If desired (and so configured), the UICC 56 / USIM application 28 can enter a personal unlocking key (PUK) locked state, which allows the stored fingerprint to be reset after successfully entering the PUK code. This will be a useful model under the assumption that the attacker cannot access the PUK code. This can correspond to a "normal user" scenario, where the PIN is not very secure (i.e., it can be set to a default value, such as 1234), but the ME 4 has enabled biometrics or other strong authentication. In this instance, an attacker may transfer the UICC 56 to an unlocked ME 4 and try to use a known or easily guessable PIN. In this instance, a "mismatch" condition that occurs before or during the PIN entry will allow the UICC 56 / USIM application 28 to prevent further use of the UICC 56. In contrast, normal users who switch MEs will assume that they have access to the PUK code. After replacing the UICC 56 with a new ME 4, all they need to do will be to enter the PUK code, reset the stored measurement data, and allow the UICC to learn the fingerprint of the new ME 4.

[0141] Subscription Hidden Identifier (SUCI): In the instance of 5G registration, the ME 4 needs to use the SUCI parameter to identify the subscription to the home MNO. 3GPP TS 31.102 v17.4.0 indicates that the identity of the subscriber (Subscription Permanent Identifier (SUPI)) can be kept confidential by the UICC 56 (Services 124 and 125 in 3GPP TS 31.102 v17.4.0) and only provided to the ME 4 in a hidden (e.g., SUCI) format. This allows the UICC 56 / USIM 28 to simply reject the SUCI from the ME 4 in a "no match" situation. Alternatively, the UICC 56 / USIM application 28 can use the encrypted portion of the SUCI as a covert channel to send information to the network 8 that cannot be interpreted or read by the ME 8. This covert channel can be used to communicate to the MNO 8 that it received a "no match" situation from the monitoring component 68 (i.e., the UICC 56 is present in a different ME 4 than the ME 4 from which the stored fingerprint was derived). Fig. 9 A SUCI embodiment is shown in FIG. 8 , which shows signaling between components of the UICC 56 , the ME 4 and the network 8 . Fig. 9 A first option of rejecting SUCI from ME 4 and a second option of using SUCI as a covert channel are shown in FIG.

[0142] Since the ME 4 cannot register itself with the network 8 without a SUCI, a SUCI request from the ME 8 to the UICC 56 / USIM application 28 is also a possible decision point.

[0143] Using SUCI as a covert channel supports remote operation of the network 8, as the covert channel can be used to inform the network 8 that the measured characteristics of the ME carrying the UICC 56 do not match the stored fingerprint. In this example, the home network 8 can become an active participant in responding to the mismatch.

[0144] The above discussion assumes a simple rejection operation in response to a mismatch (inconsistency), wherein the UICC 56 / USIM application 28 effectively stops cooperating with the ME 4 and prevents any further use of the UICC 56 until it is powered off and restarted. This action and some other local actions (i.e., actions that can be performed by the UICC / USIM itself) will be described in more detail below.

[0145] Rejection: The simplest action when a “mismatch” is detected is to simply stop cooperating with the ME 4. There are several key decision points in the ME↔UICC interaction where the behavior of the UICC has a significant impact:

[0146] 1) PIN entry, before which the PIN-protected files in the USIM application 28 are locked,

[0147] 2) SUCI search,

[0148] 3) Initial authentication to generate network key material, and

[0149] 4) "Re-authentication" - This is similar to "Authentication", except that the UICC 56 may notice the discrepancy long before re-authentication occurs (i.e., between authentication and re-authentication), but it will only be able to act on it after running the re-authentication process.

[0150] 5) Application layer authentication - Subscription credentials can be used for application layer authentication, for example via GBA or AKMA. If primary authentication has not been performed and AKMA is required, USIM access is also required in AKMA. GBA can be used at some point after (or before) initial authentication and requires access to the USIM, similar to re-authentication.

[0151] The sooner the UICC can react to a “mismatch”, the more effective the rejection strategy will be, as it allows for more response options.

[0152] PIN locked - If the UICC 56 detects a "mismatch" at any point in time (including any of the above decision points), it may record this fact in memory (e.g., in non-volatile random access memory (NVRAM)) and force a reset ("refresh" using a UICC reset as described in ETSI TS 102 203 V15.3.0 (2019-07) Smart Cards; Card Application Toolkit (CAT) (Release 15)). Subsequently, the UICC / USIM application will behave as a PIN locked UICC, requesting the user to enter a PUK code to continue. If a successful PUK code is subsequently entered, the USIM application 28 may request the monitoring component 68 to discard the stored fingerprint and establish a new ME fingerprint based on the new measurements.

[0153] "Bricked" - Using NVRAM or one-time programmable (OTP) fuses (such as eFuses), the UICC 56 can "brick" itself, i.e. disable itself (preferably permanently), making it unusable. In this case, the USIM application 28 can rewrite any sensitive stored information, such as SUPI, MNO authentication parameters, etc., before triggering the disabling operation. Although this operation is preferably irreversible, it may be considered for some applications where the UICC may be compromised. Alternatively, the disabling of the UICC 56 may be temporary, for example, using a programmed odd number of OTP fuses to indicate "bricked" and a programmed even number of OTP fuses to indicate "unbricked" (not disabled).

[0154] Hidden (1) - The UICC 56 / USIM application 28 may also choose a hiding strategy. For example, it may only record the fingerprint of the ME 4 for later analysis. The UICC 56 / USIM application 28 may disable some high-level features in the "mismatch" case, or use later OTA communication with the MNO 8 without alerting the ME 4 to being identified as a "mismatch".

[0155] Hidden (2) - In an alternative "hidden" method, the UICC 56 may contain two different subscriptions (e.g. IMSI), one of which is used in the correct ME 4 and the other is used in the event that a "mismatch" has been detected. In this case, the UICC 56 will appear to be functioning normally to the ME 4.

[0156] As described above, instead of or in addition to the UICC 56 reacting to the measurement results indicating that the fingerprint does not match, the UICC 56 may also inform the HPLMN 8 of the situation and let the network 8 react to it. For example, the HPLMN 8 may temporarily block the subscription associated with the UICC 56, or limit the subscription (e.g., reduce the available data rate and / or reduce the available services) and may initiate an investigation related to the subscription. This may, for example, mean contacting the user and asking what has happened, etc., or running remote diagnostics on the UICC 56 / ME 4 (if available). In the scenario where the ME 4 has actually been tampered with, this signaling needs to be sent in a covert manner so that the now compromised ME 4 does not notice it, otherwise the ME 4 may try to block the signaling to prevent the HPLMN 8 from discovering that something suspicious is happening.

[0157] One way that the UICC 56 can inform the HPLMN 8 and make it undetectable to the ME 4 is to include information about this measurement in the SUCI sent to the HPLMN 8 as part of the 5G registration. For each new 5G registration request, the UICC 56 regenerates the SUCI (hidden identifier) ​​from the SUPI (permanent identifier). This process requires encrypting the mobile subscription identification number (MSIN) part of the SUPI (IMSI) using a key that can only be obtained by the HPLMN 8. In this way, no entity on the communication path can know the actual subscription identifier, thereby providing privacy protection for the subscriber, while the HPLMN 8 will be able to de-hide the SUCI and obtain the corresponding SUPI. The SUCI is generated on the UICC 56, so the ME 4 cannot see the content of the hidden part of the SUCI.

[0158] This hidden part of the data may also be used to hide information about the measurements made by the UICC 56. In fact, when the UICC 56 generates the SUCI from the SUPI, the UICC 56 may not only hide the MSIN, but also information about the measurement results, for example by concatenating the MSIN with the measurement information and / or the result of a match / no match decision and then hiding the result. This may be done every time the SUCI is generated, i.e. even if there is no difference in the measurement results. This will make it more difficult for the ME 4 to detect whether the UICC 56 has noticed a problem with the fingerprint, because the length of the hidden part of the SUCI may remain the same regardless of whether the message from the monitoring component 68 is positive or negative.

[0159] Another channel for communication between the UICC 56 and the HPLMN 8 without the knowledge of the ME 4 may be based on the UICC OTA keys, which the HPLMN 8 normally uses to remotely manage files on the UICC 56. However, this would be new signalling that could be detected by the ME 4, although the ME 4 would not be able to decipher the contents of the message. The UICC OTA keys may be used by the UICC 56 to send encrypted data to the HPLMN 8, or by the HPLMN 8 to retrieve additional information from the UICC 56 based on information received in the hidden portion of the SUCI as described above.

[0160] There are also some other methods that can be used to send information about the ME fingerprinting status to the HPLMN 8. For example, the UICC 56 / USIM application 28 can use active UICC commands to send an SMS message, open a given uniform resource locator (URL) on a browser (this allows the UICC 56 to embed information into the URL and its query parameters, although this is visible to the end user / ME 4), open a data channel, etc. Regardless of the specific method, the UICC 56 can establish communication with its HPLMN 8 unless the ME 4 actively blocks the UICC 56 from communicating with the HPLMN 8.

[0161] The UICC 56 and the home MNO 8 may also agree that any successful registration must be followed by a non-replayable confirmation sent by the UICC 56 (using some of the available channels). Thus, even if SUCI cannot be reliably used as a covert channel (as it may be cached and reused by the ME 4), and all other communication channels are blocked by the ME 4, the lack of a positive match result from the UICC 56 after network registration may itself be a signal that security is compromised.

[0162] If the UICC 56 ends up in a temporary locked state, it may be necessary for the HPLMN 8 to unlock it. In this case, the HPLMN 8 may request the ME 4 to provide the measurement unit log to determine whether the abnormal measurements constitute an attack. This can also be combined with user interaction (e.g., PIN / PUK) unlocking.

[0163] Further details of an embodiment using SUCI as a covert channel to signal a fingerprint match / mismatch to the network 8 are provided below. In the network 8, the Access and Mobility Function (AMF) delegates the actual authentication of the ME 4 to the Authentication Server Function (AUSF). Logically, the UDM is the first place in the network 8 that can decrypt the SUCI and obtain the Subscriber Identity (SUPI), which is provided to the AUSF along with the authentication vector. Once authentication has been completed, the network has the subscription information and a session can be issued from the Session Management Function (SMF) and instantiated on the User Plane Function (UPF).

[0164] Upon detecting a fingerprint mismatch, the UICC 56 may generate a SUCI that appears valid but is incorrect, which the AUSF may reject. The same applies to the above-described embodiment, in which the UICC 56 stores a second set of subscription credentials that are only used in the event of a fingerprint mismatch. The AUSF may reject the SUCI outright as an authentication failure, or alternatively, the AUSF may indicate to the UICC 56 that the registration will continue, so that it appears valid to the ME 4, but does not result in a valid session. In this case, the UICC 56 and the MNO 8 may have previously agreed on a SUPI that indicates a status such as "session rejected but pretended to be successful" (note that this is slightly different from the way the indication is attached to the SUPI when the SUCI is used as a covert channel as described above). Another alternative is to have the registration result in a so-called "honeypot" session in which the HPLMN is applying additional monitoring to the ME 4.

[0165] If the fingerprint match indicator is included in the SUCI (as an extra field, or each subscriber UICC may be allocated two SUPIs, one to indicate "everything is OK" and another to indicate "match failed, device suspect").

[0166] In instances where the fingerprints do not match, the MNO may any of the following: reject authentication (AUSF fails); perform a “stealth fail” (i.e., registration / negotiation appears to complete to the ME 4, but the base station (gNB) will still reject further communications and no session is created); allow authentication to complete, but mark the session as a “bad fingerprint”, which in turn may cause the SMF to change session parameters; the UPF may add additional filtering; and / or, if there is a 5G identity delegation to an external party, the delegation may be rejected (i.e., the subscriber identity is not available to other parties such as an enterprise).

[0167] Fig.10is a flow chart illustrating a method of operating a UICC 56 according to various embodiments. In the method, the UICC 56 is located in a ME 4 referred to as a "host ME", and the UICC 56 has a fingerprint of a first ME available, which may or may not be the host ME 4. The UICC 56 may perform the method in response to executing appropriately formulated computer-readable code. The computer-readable code may be embodied or stored on a computer-readable medium (e.g., a memory chip, an optical disk, or other storage medium, including a UICC). The computer-readable medium may be part of a computer program product.

[0168] Fig.10 The method in may be performed in a variety of different situations, including: when the UICC 56 is initialized in the host ME 4; continuously or periodically during operation of the UICC 56 in the host ME 4; before or during a network registration process in which the host ME 4 registers with the network 8; before a user code is used to unlock a function of the UICC 56 in the host ME 4; when the host ME 4 requests to hide the identifier; when authentication is requested from the UICC 56; and when the host ME 4 requests SUCI.

[0169] In step 1002, the UICC 56 measures one or more characteristics of the host ME 4. These characteristics may be measured by one or more probes in the UICC 56. The characteristics of the host ME 4 that can be measured may include any one or more of the following items: electrical parameters, voltage parameters, communication parameters, signal levels, duty cycle lengths, one or more parameters of a clock signal provided by the host ME to the UICC, one or more electrical parameters of a logic signal, one or more parameters related to a data link protocol, one or more parameters related to a transport protocol, one or more parameters related to an application selection protocol, an order of accessing directories and / or files in a UICC main directory, an order of accessing directories and / or files in a USIM application directory, an order of commands issued by the host ME 4, command parameters, and / or timing information of commands.

[0170] In step 1004 , the UICC 56 determines whether the characteristic measurement value of the host ME 4 is consistent with a first ME fingerprint corresponding to the first ME 4 .

[0171] In step 1006, if the characteristic measurement value of the host ME 4 is inconsistent with the first ME fingerprint, the UICC 56 performs a first action.

[0172] A number of different options may be used for the first action. In some embodiments, the UICC 56 may be capable of performing several of the first actions listed below, in which case the UICC 56 may select the most appropriate first action to be taken in step 1006 if the characteristic measurement of the host ME 4 is determined to be inconsistent with the first ME fingerprint. Alternatively, the UICC 56 may be configured to perform only one of the first actions listed below, in which case the UICC 56 performs that action in step 1006 if the characteristic measurement of the host ME 4 is determined to be inconsistent with the first ME fingerprint.

[0173] The first action can be any of the following: - avoid providing the host ME 4 with information required for the host ME 4 to register and / or authenticate with the network 8; - reject any user code (e.g. PIN) entered into the host ME 4 that would unlock the functionality of the UICC 56 in the host ME 4; - activating the UICC 56 lock mode (e.g. requiring the PUK of the UICC 56 to be entered into the host ME 4); - activating the UICC 56 lock mode and deleting or resetting the first ME fingerprint; - avoid providing hidden identifiers to the host ME 4; - avoid providing SUCI to the host ME 4; - providing the host ME 4 with a modified hidden identifier to be sent to the home network 8. The modified hidden identifier may be derived from a subscribed identifier associated with the UICC 56 and information indicating that the characteristic measurement of the host ME 4 is inconsistent with the first ME fingerprint; - providing the host ME 4 with a modified SUCI to be sent to the home network 8. The modified SUCI may be derived from the SUPI and the information indicating that the characteristic measurement of the host ME 4 is inconsistent with the first ME fingerprint; - sending a notification to the network 8 that the characteristic measurement value of the host ME 4 is inconsistent with the first ME fingerprint; - deleting or rewriting subscription information stored in the UICC 56; - providing authentication information of a secondary subscription stored on the UICC 56 (e.g. where the UICC 56 stores a primary subscription to be used if the characteristic measurement of the host ME 4 is consistent with the first ME fingerprint and a secondary subscription to be used if the characteristic measurement is inconsistent); - temporarily disabling the operation of the UICC 56; - permanently disabling the operation of the UICC 56; and - storing the characteristic measurements of the Host ME 4 (in this case the UICC 56 may wait for a period of time before communicating the inconsistency to the Network 8).

[0174] In some embodiments, the first ME fingerprint is derived from measured values ​​of one or more characteristics of the first ME. Therefore, in some embodiments, when the UICC 56 is mounted in the first ME, the method in the UICC 56 further includes: measuring one or more characteristics of the first ME, and determining the first ME fingerprint of the first ME based on the measured characteristics of the first ME.

[0175] In some embodiments, the first ME fingerprint includes one or more statistics. In these embodiments, step 1004 may include comparing characteristic measurements of the host ME 4 and / or one or more statistics derived from characteristic measurements of the host ME 4 with the statistics included in the first ME fingerprint.

[0176] In alternative embodiments, the first ME fingerprint includes one or more model weights of the ML model. In these embodiments, step 1004 may include: inputting the characteristic measurement value of the host UE 4 into the ML model configured according to the one or more model weights, and determining whether the characteristic measurement value of the host ME 4 is consistent with the first ME fingerprint based on the output of the ML model.

[0177] In some embodiments, the method further comprises: if the characteristic measurement value of the host ME 4 is found to be consistent with the first ME fingerprint in step 1004, the UICC 56 performs a second action.

[0178] The second action may be any one or more of: providing the host ME 4 with information required for the host ME 4 to register and / or authenticate with the network 8; unlocking the functionality of the UICC 56; providing authentication information of the primary subscription stored on the UICC 56; providing the host ME 4 with a hidden identifier; and providing the host ME 4 with a SUCI.

[0179] Fig.11 is a flow chart illustrating another method of operating a UICC 56 according to various embodiments. In the method, the UICC 56 is located in a ME 4 referred to as a "first ME", and in the method, the UICC 56 determines a fingerprint of the first ME 4. The UICC 56 may perform the method in response to executing appropriately formulated computer-readable code. The computer-readable code may be embodied or stored on a computer-readable medium (e.g., a memory chip, an optical disk, or other storage medium, including a UICC). The computer-readable medium may be part of a computer program product.

[0180] In step 1102 , the UICC 56 measures one or more characteristics of the first ME 4 .

[0181] In step 1104, the UICC 56 determines a first ME fingerprint of the first ME 4 based on the characteristic measurements.

[0182] In some embodiments, the first ME fingerprint includes one or more statistics, and step 1104 includes analyzing characteristic measurements of the first ME 4 to determine one or more statistics representative of the first ME 4. In some embodiments, the one or more statistics include mean and / or variance information of the one or more characteristics.

[0183] In alternative embodiments, the first ME fingerprint comprises one or more model weights of the ML model, and step 1104 comprises training or updating the ML model using the characteristic measurements of the first ME, such that the trained or updated ML model is capable of providing an output indicating whether the characteristic measurements input to the ML model are consistent with the first ME. In these embodiments, the first ME fingerprint is determined as one or more model weights of the trained or updated ML model.

[0184] In some embodiments, the UICC 56 may execute Fig.10 The method shown and Fig.11 The method shown.

[0185] Fig.12 is a flow chart illustrating a method of operating one or more network nodes in a communication network according to various embodiments. Fig.11 Each step in can be performed by the same network node, or Fig.11 The different steps in may be performed by two or more network nodes. One or more network nodes may be nodes in a radio access network (RAN), such as a base station (e.g., an eNB in ​​a long term evolution (LTE) network or a gNB in ​​a new radio (NR)), or may include nodes in a radio access network (RAN), such as a base station (e.g., an eNB in ​​a long term evolution (LTE) network or a gNB in ​​a new radio (NR)); and / or one or more network nodes may be nodes in a core network, such as a network node responsible for authenticating ME4 to the network, or may include nodes in a core network, such as a network node responsible for authenticating ME4 to the network. One or more network nodes may perform the method in response to executing appropriately formulated computer-readable code. The computer-readable code may be embodied or stored on a computer-readable medium (e.g., a memory chip, an optical disk, or other storage medium). The computer-readable medium may be part of a computer program product.

[0186] In step 1202 , the network node receives a first message from a host ME 4 that is registering and / or authenticating with the network 8 or has registered and / or authenticated with the network 8 .

[0187] In step 1204 , the network node processes the first message to extract an indication of whether the UICC 56 in the host ME 4 considers the characteristic measurement value of the host ME 4 to be consistent with a first ME fingerprint corresponding to the first ME 4 .

[0188] In step 1206, the network node performs an action based on the extracted indication.

[0189] In some embodiments, the first message is or includes a hidden identifier or SUCI. In these embodiments, the extracted indication may include information encoded in the hidden identifier or SUCI indicating whether the characteristics of the host ME 4 are consistent with the first ME fingerprint.

[0190] In an alternative embodiment, the first message may be or include information encrypted using an OTA key previously provided by the network 8 to the UICC 56 .

[0191] In an alternative embodiment, the first message may be an SMS message.

[0192] In some embodiments, if the indication indicates that the UICC believes that the characteristic measurement value of the host ME is inconsistent with the first ME fingerprint corresponding to the first ME, the network node may also perform any one or more of the following: blocking or preventing the host ME 4 from accessing the network 8; reducing or limiting the services provided by the network 8 to the host ME 4; and sending a second message to the subscriber associated with the UICC 56 to query the inconsistency.

[0193] Fig.13A network node 1300 that can be used to implement the above method according to some embodiments is shown. As used herein, a network node refers to a device that can, is configured, is arranged and / or is operable to communicate directly or indirectly with a UE and / or with other network nodes or devices in a telecommunications network. Examples of network nodes include, but are not limited to, access network nodes such as access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, NodeBs, evolved NodeBs (eNBs), and NR NodeBs (gNBs)). Other examples of network nodes include, but are not limited to, core network nodes, such as nodes including the functions of one or more of the following items: a mobile switching center (MSC), a mobility management entity (MME), a home subscriber server (HSS), an access and mobility management function (AMF), a session management function (SMF), an authentication server function (AUSF), a subscription identifier de-hiding function (SIDF), a unified data management (UDM), a security edge protection proxy (SEPP), a network open function (NEF), and / or a user plane function (UPF).

[0194] Base stations may be classified based on the amount of coverage they provide (or in other words, their transmit power level), and thus may be referred to as femto, pico, micro or macro base stations, depending on the amount of coverage provided. A base station may be a relay node or a relay donor node that controls a relay. A network node may also include one or more (or all) parts of a distributed radio base station, such as a centralized digital unit and / or a remote radio unit (RRU), sometimes referred to as a remote radio head (RRH). These remote radio units may or may not be integrated with an antenna as an antenna-integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0195] Other examples of network nodes include a multi-transmission point (multi-TRP) 5G access node, a multi-standard radio (MSR) device (such as an MSR BS), a network controller (such as a radio network controller (RNC) or a base station controller (BSC)), a base transceiver station (BTS), a transmission point, a transmission node, a multi-cell / multicast coordination entity (MCE), an operation and maintenance (O&M) node, an operation support system (OSS) node, a self-organizing network (SON) node, a positioning node (e.g., an evolved serving mobile location center (E-SMLC)), and / or minimization of drive tests (MDT).

[0196] The network node 1300 includes a processing circuit 1302, a memory 1304, a communication interface 1306 and a power supply 1308, and / or any other components or any combination thereof. The network node 1300 may be composed of multiple physically separated components (e.g., NodeB components and RNC components, BTS components and BSC components, etc.), each of which may have its own corresponding components. In certain scenarios where the network node 1300 includes multiple separate components (e.g., BTS and BSC components), one or more separate components may be shared between several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique "NodeB and RNC pair" may be considered as a single separate network node in some cases. In some embodiments, the network node 1300 may be configured to support multiple radio access technologies (RATs). In such an embodiment, some components may be duplicated (e.g., separate memory 1304 exists for different RATs), and some components may be reused (e.g., the same antenna 1310 may be shared by different RATs). The network node 1300 may also include multiple sets of the various components shown for different wireless technologies (e.g., GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, radio frequency identification (RFID), or Bluetooth wireless technologies) integrated into the network node 1300. These wireless technologies may be integrated into the same or different chips or chipsets and other components within the network node 1300.

[0197] The processing circuit 1302 may include a combination of one or more of the following: a microprocessor, a controller, a microcontroller, a central processing unit, a digital signal processor, an application specific integrated circuit, a field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic, which is operable to provide network node 1300 functions alone or in combination with other network node 1300 components (e.g., memory 1304). For example, the processing circuit 1302 may be configured to cause the network node to execute reference Fig.12 Part or all of the methods described.

[0198] In some embodiments, processing circuitry 1302 includes a system on a chip (SOC). In some embodiments, processing circuitry 1302 includes one or more of radio frequency (RF) transceiver circuitry 1312 and baseband processing circuitry 1314. In some embodiments, radio frequency (RF) transceiver circuitry 1312 and baseband processing circuitry 1314 may be on separate chips (or chipsets), boards, or units (e.g., a radio unit and a digital unit). In alternative embodiments, part or all of RF transceiver circuitry 1312 and baseband processing circuitry 1314 may be on the same chip or chipset, board, or unit set.

[0199] The memory 1304 may include any form of volatile or non-volatile computer-readable memory, including but not limited to permanent storage devices, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (e.g., hard disk), removable storage media (e.g., flash drive, compact disk (CD) or digital video disk (DVD)), and / or any other volatile memory or non-volatile, non-transitory device-readable and / or computer-executable memory device that stores information, data and / or instructions that can be used by the processing circuit 1302. The memory 1304 may store any suitable instructions, data or information, including computer programs, software, applications including one or more of logic, rules, codes, tables, and / or other instructions that can be executed by the processing circuit 1302 and used by the network node 1300. The memory 1304 may be used to store any calculations performed by the processing circuit 1302 and / or any data received via the communication interface 1306. In some embodiments, the processing circuit 1302 and the memory 1304 are integrated together.

[0200] The communication interface 1306 is used for wired or wireless communication of signaling and / or data between network nodes, access networks, core networks and / or UEs. As shown, the communication interface 1306 includes a port / terminal 1316 for sending data to the network and receiving data from the network, for example, via a wired connection.

[0201] In an embodiment where the network node 1300 is an access network node, the communication interface 1306 also includes a radio front-end circuit 1318 that can be coupled to the antenna 1310 or, in some embodiments, is part of the antenna 1310. In an embodiment where the network node 1300 is a core network node, the core network node may not include the radio front-end circuit 1318 and the antenna 1310. The radio front-end circuit 1318 includes a filter 1320 and an amplifier 1322. The radio front-end circuit 1318 can be connected to the antenna 1310 and the processing circuit 1302. The radio front-end circuit can be configured to adjust the signal transmitted between the antenna 1310 and the processing circuit 1302. The radio front-end circuit 1318 can receive digital data to be sent to other network nodes or UEs via a wireless connection. The radio front-end circuit 1318 can convert the digital data into a radio signal with appropriate channel and bandwidth parameters using a combination of the filter 1320 and / or the amplifier 1322. The radio signal can then be sent via the antenna 1310. Similarly, when data is received, antenna 1310 may collect the radio signal, which may then be converted to digital data by radio front end circuit 1318. The digital data may be passed to processing circuit 1302. In other embodiments, the communication interface may include different components and / or different combinations of components.

[0202] In some alternative embodiments, the access network node 1300 does not include a separate radio front end circuit 1318, instead the processing circuit 1302 includes the radio front end circuit and is connected to the antenna 1310. Similarly, in some embodiments, all or some of the RF transceiver circuit 1312 is part of the communication interface 1306. In yet another embodiment, the communication interface 1306 includes one or more ports or terminals 1316, the radio front end circuit 1318, and the RF transceiver circuit 1312 as part of a radio unit (not shown), and the communication interface 1306 communicates with the baseband processing circuit 1314, which is part of the digital unit (not shown).

[0203] Antenna 1310 may include one or more antennas or antenna arrays configured to send and / or receive wireless signals. Antenna 1310 may be coupled to radio front end circuit 1318 and may be any type of antenna capable of wirelessly sending and receiving data and / or signals. In some embodiments, antenna 1310 is separate from network node 1300 and may be connected to network node 1300 via an interface or port.

[0204] Antenna 1310, communication interface 1306 and / or processing circuit 1302 may be configured to perform any receiving operation and / or certain obtaining operations performed by a network node as described herein. Any information, data and / or signal may be received from a UE, another network node and / or any other network device. Similarly, antenna 1310, communication interface 1306 and / or processing circuit 1302 may be configured to perform any sending operation performed by a network node as described herein. Any information, data and / or signal may be sent to a UE, another network node and / or any other network device.

[0205] The power supply 1308 provides power to the various components of the network node 1300 in a form suitable for the various components (e.g., at the voltage and current levels required by each corresponding component). The power supply 1308 may also include power management circuitry or be coupled to a power management circuitry to supply power to the components of the network node 1300 for performing the functions described herein. For example, the network node 1300 may be connected to an external power source (e.g., a power grid, a power outlet) via an input circuit or interface (e.g., a cable), whereby the external power source supplies power to the power circuit of the power supply 1308. As another example, the power supply 1308 may include a power source in the form of a battery or a battery pack, which is connected to the power circuit or integrated in the power circuit. If the external power source fails, the battery may provide backup power.

[0206] Embodiments of network node 1300 may include beyond Fig.13 Additional components to the components shown are used to provide certain aspects of the functionality of the network node (including any functionality described herein and / or any functionality required to support the subject matter described herein). For example, the network node 1300 may include a user interface device to allow information to be input into the network node 1300 and to allow information to be output from the network node 1300. This may allow a user to perform diagnostic, maintenance, repair, and other management functions for the network node 1300.

[0207] Although the computing devices described herein (e.g., ME, UICC, UE, network node, etc.) may include a combination of the hardware components shown, other embodiments may include computing devices with different combinations of components. It should be understood that these computing devices may include any suitable combination of hardware and / or software required to perform the tasks, features, functions, and methods disclosed herein. The determination, calculation, acquisition, or similar operations described herein may be performed by a processing circuit, which may process information by, for example, converting the obtained information to other information, comparing the obtained information or the converted information with information stored in the network node, and / or performing one or more operations based on the obtained information or the converted information, and making a determination based on the result of the processing. In addition, although the components are depicted as a single box located within a larger box or nested within multiple boxes, in reality, the computing device may include multiple different physical components that constitute a single illustrated component, and the functions may be divided between separate components. For example, a communication interface may be configured to include any component described herein, and / or the functions of the components may be divided between the processing circuit and the communication interface. In another example, the non-computationally intensive functions of any such component may be implemented in software or firmware, and the computationally intensive functions may be implemented in hardware.

[0208] In some embodiments, some or all of the functions described herein may be provided by a processing circuit that executes instructions stored in a memory, which in some embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functions may be provided by a processing circuit, for example, in a hardwired manner, without executing instructions stored on a separate or discrete device-readable storage medium. In any of these specific embodiments, the processing circuit may be configured to perform the described functions, regardless of whether instructions stored on a non-transitory computer-readable storage medium are executed. The benefits provided by such functionality are not limited to separate processing circuits or to other components of a computing device, but are enjoyed by the computing device as a whole and / or are generally enjoyed by end users and wireless networks.

[0209] The above merely illustrates the principles of the present disclosure. In view of the teachings herein, various modifications and changes to the described embodiments will be apparent to those skilled in the art. Therefore, it should be understood that those skilled in the art will be able to design many systems, arrangements and programs that, although not explicitly shown or described herein, embody the principles of the present disclosure and are therefore within the scope of the present disclosure. As will be understood by those of ordinary skill in the art, the various exemplary embodiments may be used together or interchangeably with one another.

[0210] abbreviation

[0211] At least some of the following abbreviations may be used in the present disclosure. If there is an inconsistency between abbreviations, how it is used above shall take precedence. If listed multiple times below, the first listing shall take precedence over any subsequent listings.

[0212] Authentication and key management for AKMA applications

[0213] APDU Application Protocol Data Unit

[0214] CK Confidentiality Key

[0215] EF Basic Files

[0216] eSIM embedded subscriber identity module

[0217] FDR Frequency Domain Reflectometry

[0218] GBA Generic Boot Architecture

[0219] HPLMN Home Public Land Mobile Network

[0220] HW Hardware

[0221] IK Integrity Key

[0222] IMEI International Mobile Equipment Identity,

[0223] IMSI International Mobile Subscriber Identity

[0224] iSIM Integrated Subscriber Identity Module

[0225] ME Mobile Devices

[0226] MF Master File

[0227] MNO Mobile Network Operator

[0228] NVM Non-volatile Memory

[0229] NVRAM Non-volatile Random Access Memory

[0230] OS operating system,

[0231] OWF One-Way Function

[0232] PHY

[0233] PIN Personal Identification Number

[0234] PUF Physical Unclonable Function

[0235] PUK Personal Unblocking Key

[0236] RAND Random Challenge

[0237] RX Receiver

[0238] SIM Subscriber Identity Module

[0239] SUCI Subscribe Hide Logo

[0240] SUPI Subscription Permanent Identifier

[0241] SW Software

[0242] TEE Trusted Execution Environment

[0243] TPM Trusted Platform Module

[0244] TDR Time Domain Reflectometry

[0245] TX Transmitter

[0246] UICC Universal Integrated Circuit Card

[0247] URL Uniform Resource Locator

[0248] USIM Universal Subscriber Identity Module

[0249] 3GPP Third Generation Partnership Project

[0250] 5G Fifth Generation

[0251] 6G Sixth Generation

[0252] ABS Almost Blank Subframe

[0253] ARQ Automatic Repeat Request

[0254] AWGN Additive White Gaussian Noise

[0255] BCCH Broadcast Control Channel

[0256] BCH Broadcast Channel

[0257] CA Carrier Aggregation

[0258] CC Carrier Component

[0259] CCCH SDU Common Control Channel SDU

[0260] CDMA Code Division Multiple Access

[0261] CGI Cell Global Identifier

[0262] CIR Channel Impulse Response

[0263] CP Cyclic Prefix

[0264] CPICH Common Pilot Channel

[0265] CPICH Ec / No CPICH received energy per chip divided by the power density in the frequency band

[0266] CQI Channel Quality Information

[0267] C-RNTI Cell RNTI

[0268] CSI Channel State Information

[0269] DCCH Dedicated Control Channel

[0270] DL Downlink

[0271] DM Demodulation

[0272] DMRS Demodulation Reference Signal

[0273] DRX Discontinuous Reception

[0274] DTX Discontinuous Transmission

[0275] DTCH Dedicated Traffic Channel

[0276] DUT Device Under Test

[0277] E-CID Enhanced Cell ID (positioning method)

[0278] eMBMS Evolved Multimedia Broadcast / Multicast Service

[0279] E-SMLC Evolved Serving Mobile Location Center

[0280] ECGI Evolved CGI

[0281] eNB E-UTRAN NodeB

[0282] EPDCCH Enhanced Physical Downlink Control Channel

[0283] E-SMLC Evolved Serving Mobile Location Center

[0284] E-UTRA Evolved UTRA

[0285] E-UTRAN Evolved UTRAN

[0286] FDD Frequency Division Duplex

[0287] FFS For further study

[0288] Base stations in gNB NR

[0289] GNSS Global Navigation Satellite System

[0290] HARQ Hybrid Automatic Repeat Request

[0291] HO Switchover

[0292] HSPA High Speed ​​Packet Access

[0293] HRPD High Rate Packet Data

[0294] LOS Line of Sight

[0295] LPP LTE Positioning Protocol

[0296] LTE Long Term Evolution

[0297] MAC Media Access Control

[0298] MAC Message Authentication Code

[0299] MBSFN Multimedia Broadcast Multicast Service Single Frequency Network

[0300] MBSFNABS MBSFN Almost Blank Subframes

[0301] MDT Minimization of Drive Test

[0302] MIB Master Information Block

[0303] MME Mobility Management Entity

[0304] MSC Mobile Switching Center

[0305] PDCCH Narrowband Physical Downlink Control Channel

[0306] NR New Radio

[0307] OCNG OFDMA Channel Noise Generator

[0308] OFDM Orthogonal Frequency Division Multiplexing

[0309] OFDMA Orthogonal Frequency Division Multiple Access

[0310] OSS Operation Support System

[0311] OTDOA Observed Time Difference of Arrival

[0312] O&M Operation and Maintenance

[0313] PBCH Physical Broadcast Channel

[0314] P-CCPCH Primary Common Control Physical Channel

[0315] PCell Primary Cell

[0316] PCFICH Physical Control Format Indicator Channel

[0317] PDCCH Physical Downlink Control Channel

[0318] PDCP Packet Data Convergence Protocol

[0319] PDP Profile Delay Profile

[0320] PDSCH Physical Downlink Shared Channel

[0321] PGW Packet Gateway

[0322] PHICH Physical Hybrid ARQ Indicator Channel

[0323] PLMN Public Land Mobile Network

[0324] PMI Precoding matrix indicator

[0325] PRACH Physical Random Access Channel

[0326] PRS Positioning Reference Signal

[0327] PSS Primary Synchronization Signal

[0328] PUCCH Physical Uplink Control Channel

[0329] PUSCH Physical Uplink Shared Channel

[0330] RACH Random Access Channel

[0331] QAM Quadrature Amplitude Modulation

[0332] RAN Radio Access Network

[0333] RAT Radio Access Technology

[0334] RLC Radio Link Control

[0335] RLM Radio Link Management

[0336] RNC Radio Network Controller

[0337] RNTI Radio Network Temporary Identifier

[0338] RRC Radio Resource Control

[0339] RRM Radio Resource Management

[0340] RS reference signal

[0341] RSCP Received Signal Code Power

[0342] RSRP Reference Symbol Received Power or Reference Signal Received Power

[0343] RSRQ Reference Signal Received Quality or Reference Symbol Received Quality

[0344] RSSI Received Signal Strength Indicator

[0345] RSTD Reference Signal Time Difference

[0346] SCH Synchronization Channel

[0347] SCell Secondary Cell

[0348] SDAP Service Data Adaptation Protocol

[0349] SDU Service Data Unit

[0350] SFN System Frame Number

[0351] SGW Service Gateway

[0352] SI System Information

[0353] SIB System Information Block

[0354] SNR Signal to Noise Ratio

[0355] SON Self-Optimizing Network

[0356] SS Sync Signal

[0357] SSS Secondary synchronization signal

[0358] TDD Time Division Duplex

[0359] TDOA Time Difference of Arrival

[0360] TOA Time of Arrival

[0361] TSS three-level synchronization signal

[0362] TTI Transmission Time Interval

[0363] UE User Equipment

[0364] UL Uplink

[0365] UMTS Universal Mobile Telecommunications System

[0366] USIM Universal Subscriber Identity Module

[0367] UTDOA Uplink Time Difference of Arrival

[0368] UTRA UMTS Terrestrial Radio Access

[0369] UTRAN UTRA Network

[0370] WCDMA Wide CDMA

[0371] WLAN Wide Area Network.

Claims

1. A method for operating a universal integrated circuit card UICC (56) in a host mobile equipment ME (4), the method comprising: measuring (1002) one or more characteristics of the host ME (4); determining ( 1004 ) whether a characteristic measurement value of the host ME ( 4 ) is consistent with a first ME fingerprint corresponding to a first ME; as well as If the characteristic measurement value of the host ME (4) is inconsistent with the first ME fingerprint, a first action is performed (1006).

2. The method according to claim 1, wherein: The one or more characteristics include any one or more of the following: Electrical parameters, voltage parameters, communication parameters, signal levels, duty cycle length, one or more parameters of a clock signal provided by the ME carrying the UICC (56) to the UICC (56), one or more electrical parameters of a logic signal, one or more parameters related to a data link protocol, one or more parameters related to a transport protocol, one or more parameters related to an application selection protocol, the order of accessing directories and / or files in a main directory of the UICC (56), the order of accessing directories and / or files in an application directory of a universal subscriber identity module (USIM), the order of commands issued by the ME carrying the UICC (56), command parameters and / or command timing information.

3. The method according to claim 1 or 2, wherein: The characteristic is measured by one or more probes in the UICC (56).

4. The method according to any one of claims 1 to 3, wherein: The method is performed in any one or more of the following situations: - when the UICC (56) is initialized in the host ME (4); - continuously or periodically during operation of the UICC (56) in the host ME (4); - before or during a network registration process in which the host ME (4) is to register with the network; - before using a user code to unlock the functionality of a UICC (56) in said host ME (4); - when the host ME (4) requests hiding of the identifier; - when authentication is requested from said UICC (56); and - When the host ME (4) requests to subscribe to the hidden identifier SUCI.

5. The method according to any one of claims 1 to 4, wherein: The first ME fingerprint is derived from measurements of one or more characteristics of the first ME.

6. The method according to any one of claims 1 to 5, wherein: The first ME fingerprint comprises one or more statistical values, and wherein the step of determining (1004) whether the characteristic measurement values ​​of the host ME (4) are consistent with the first ME fingerprint comprises: comparing the characteristic measurement values ​​of the host ME (4) and / or one or more statistical values ​​derived from the characteristic measurement values ​​of the host ME (4) with the statistical values ​​included in the first ME fingerprint.

7. The method according to any one of claims 1 to 5, wherein: The first ME fingerprint comprises one or more model weights of a machine learning ML model, and wherein the step of determining (1004) whether the characteristic measurement value of the host ME (4) is consistent with the first ME fingerprint comprises: inputting the characteristic measurement value of the host UE into the ML model configured according to the one or more model weights, and determining whether the characteristic measurement value of the host ME (4) is consistent with the first ME fingerprint based on the output of the ML model.

8. The method according to any one of claims 1 to 7, wherein: When the UICC (56) is mounted in the first ME, the method further includes: measuring (1102) one or more characteristics of the first ME; and A first ME fingerprint of the first ME is determined ( 1102 ) based on measured characteristics of the first ME.

9. The method according to any one of claims 1 to 8, wherein: Performing the first action includes any one or more of the following: - avoiding providing the host ME (4) with information required for the host ME (4) to register and / or authenticate with the network; - reject any user code entered into said host ME (4) that would unlock the functionality of a UICC (56) in said host ME (4); - activating the UICC (56) lock mode; - activating the UICC (56) lock mode and deleting or resetting the first ME fingerprint; - avoid providing a hidden identifier to said host ME (4); - avoid providing the Subscription Hidden Identifier SUCI to the host ME (4); - providing the host ME (4) with a modified hidden identifier to be sent to a home network, wherein the modified hidden identifier is derived from a subscribed identifier associated with the UICC (56) and information indicating that a characteristic measurement of the host ME (4) is inconsistent with the first ME fingerprint; - providing the host ME (4) with a modified SUCI to be sent to a home network, wherein the modified SUCI is derived from a subscription permanent identifier SUPI and information indicating that a characteristic measurement value of the host ME (4) is inconsistent with the first ME fingerprint; - sending a notification to the network that the characteristic measurement value of the host ME (4) is inconsistent with the first ME fingerprint; - deleting or rewriting subscription information stored in the UICC (56); - providing authentication information of a secondary subscription stored on said UICC (56); - temporarily disabling the operation of said UICC (56); - permanently disabling the operation of said UICC (56); and - Storing characteristic measurements of the host ME (4).

10. The method according to any one of claims 1 to 9, wherein: The method further comprises: If the characteristic measurement value of the host ME (4) is consistent with the first ME fingerprint, a second action is performed.

11. The method according to claim 10, wherein: The second action includes any one or more of the following: - providing the host ME (4) with information required for the host ME (4) to register and / or authenticate with the network; - unlocking the functionality of the UICC (56); - providing authentication information of a primary subscription stored on said UICC (56); - providing a hidden identifier to said host ME (4); as well as - Provide a Subscription Hidden Identifier SUCI to the host ME (4).

12. A method for operating a universal integrated circuit card UICC (56) in a first mobile equipment ME, the method comprising: measuring (1102) one or more characteristics of the first ME; as well as A first ME fingerprint of the first ME is determined ( 1104 ) based on the characteristic measurements.

13. The method according to claim 12, wherein: The first ME fingerprint comprises one or more statistical values, and wherein the step of determining the first ME fingerprint comprises: The characteristic measurements of the first ME are analyzed to determine one or more statistics representative of the first ME.

14. The method according to claim 13, wherein: The one or more statistical values ​​include mean and / or variance information of the one or more characteristics.

15. The method according to claim 12, wherein: The first ME fingerprint comprises one or more model weights of a machine learning ML model, and wherein the step of determining the first ME fingerprint comprises: The ML model is trained or updated using the characteristic measurements of the first ME, such that the trained or updated ML model is capable of providing an output indicating whether the characteristic measurements input to the ML model are consistent with the first ME, and the first ME fingerprint is determined as one or more model weights of the trained or updated ML model.

16. A method of operating a universal integrated circuit card, UICC (56), comprising performing a method according to any one of claims 12 to 15, followed by performing a method according to any one of claims 1 to 11.

17. A method of operating one or more network nodes in a network, the method comprising: receiving (1202) a first message from a host mobile device ME that is registering and / or authenticating with the network or has registered and / or authenticated with the network; processing (1204) the first message to extract an indication of whether a Universal Integrated Circuit Card UICC (56) in the host ME (4) considers a characteristic measurement value of the host ME (4) to be consistent with a first ME fingerprint corresponding to a first ME; and An action is performed ( 1206 ) based on the extracted indication.

18. The method according to claim 17, wherein: The first message is a hidden identifier or a subscription hidden identifier SUCI, or includes a hidden identifier or SUCI.

19. The method according to claim 18, wherein: The extracted indication comprises information encoded in the hidden identifier or the SUCI indicating whether the characteristics of the host ME (4) are consistent with the first ME fingerprint.

20. The method according to claim 17, wherein: The first message is or includes information encrypted using an over-the-air OTA key previously provided by the network to the UICC (56).

21. The method according to claim 17, wherein: The first message is a Short Message Service SMS message.

22. The method according to any one of claims 17 to 21, wherein: If the indication indicates that the UICC (56) considers that the characteristic measurement value of the host ME (4) is inconsistent with a first ME fingerprint corresponding to the first ME, the method further comprises any one or more of the following: blocking or preventing the host ME (4) from accessing the network; reducing or limiting services provided by said network to said host ME (4); and A second message is sent to a subscriber associated with the UICC (56) to query for inconsistencies.

23. A computer program product comprising a computer readable medium having computer readable code embodied therein, the computer readable code being configured such that, when executed by a suitable computer or processor, the computer or processor is caused to perform the method according to any one of claims 1 to 22.

24. A universal integrated circuit card UICC (56) for a host mobile equipment ME (4), the UICC (56) being configured to: measuring one or more characteristics of the host ME (4); determining whether the characteristic measurement value of the host ME (4) is consistent with a first ME fingerprint corresponding to a first ME; and If the characteristic measurement value of the host ME (4) is inconsistent with the first ME fingerprint, a first action is performed.

25. The UICC (56) according to claim 24, wherein: The one or more characteristics include any one or more of the following: Electrical parameters, voltage parameters, communication parameters, signal levels, duty cycle length, one or more parameters of a clock signal provided by the ME carrying the UICC (56) to the UICC (56), one or more electrical parameters of a logic signal, one or more parameters related to a data link protocol, one or more parameters related to a transport protocol, one or more parameters related to an application selection protocol, the order of accessing directories and / or files in a main directory of the UICC (56), the order of accessing directories and / or files in an application directory of a universal subscriber identity module (USIM), the order of commands issued by the ME carrying the UICC (56), command parameters and / or command timing information.

26. The UICC (56) according to claim 24 or 25, wherein: The characteristic is measured by one or more probes (60; 64; 66) in the UICC (56).

27. The UICC (56) according to any one of claims 24 to 26, wherein: The UICC (56) is configured to measure the one or more characteristics in any one or more of the following situations: - when the UICC (56) is initialized in the host ME (4); - continuously or periodically during operation of the UICC (56) in the host ME (4); - before or during a network registration process in which the host ME (4) is to register with the network; - before using a user code to unlock the functionality of a UICC (56) in said host ME (4); - when the host ME (4) requests hiding of the identifier; - when authentication is requested from the UICC (56); and - When the host ME (4) requests to subscribe to the hidden identifier SUCI.

28. The UICC (56) according to any one of claims 24 to 27, wherein: The first ME fingerprint is derived from measurements of one or more characteristics of the first ME.

29. The UICC (56) according to any one of claims 24 to 28, wherein: The first ME fingerprint comprises one or more statistical values, and wherein the UICC (56) is configured to determine whether the characteristic measurement values ​​of the host ME (4) are consistent with the first ME fingerprint by comparing the characteristic measurement values ​​of the host ME (4) and / or one or more statistical values ​​derived from the characteristic measurement values ​​of the host ME (4) with the statistical values ​​included in the first ME fingerprint.

30. The UICC (56) according to any one of claims 24 to 28, wherein: The first ME fingerprint comprises one or more model weights of a machine learning (ML) model, and wherein the UICC (56) is configured to determine whether the characteristic measurement value of the host ME (4) is consistent with the first ME fingerprint by: inputting the characteristic measurement value of the host UE into the ML model configured according to the one or more model weights, and determining whether the characteristic measurement value of the host ME (4) is consistent with the first ME fingerprint based on an output of the ML model.

31. A UICC (56) according to any one of claims 24 to 30, wherein: The UICC (56) is further configured to: When the UICC (56) is mounted in the first ME, measuring one or more characteristics of the first ME; and A first ME fingerprint of the first ME is determined based on measured characteristics of the first ME.

32. A UICC (56) according to any one of claims 24 to 31, wherein: Performing the first action includes any one or more of the following: - avoiding providing the host ME (4) with information required for the host ME (4) to register and / or authenticate with the network; - reject any user code entered into said host ME (4) that would unlock the functionality of a UICC (56) in said host ME (4); - activating the UICC (56) lock mode; - activating the UICC (56) lock mode and deleting or resetting the first ME fingerprint; - avoid providing a hidden identifier to said host ME (4); - avoid providing the Subscription Hidden Identifier SUCI to the host ME (4); - providing the host ME (4) with a modified hidden identifier to be sent to a home network, wherein the modified hidden identifier is derived from a subscribed identifier associated with the UICC (56) and information indicating that a characteristic measurement of the host ME (4) is inconsistent with the first ME fingerprint; - providing the host ME (4) with a modified SUCI to be sent to a home network, wherein the modified SUCI is derived from a subscription permanent identifier SUPI and information indicating that a characteristic measurement value of the host ME (4) is inconsistent with the first ME fingerprint; - sending a notification to the network that the characteristic measurement value of the host ME (4) is inconsistent with the first ME fingerprint; - deleting or rewriting subscription information stored in the UICC (56); - providing authentication information of a secondary subscription stored on said UICC (56); - temporarily disabling the operation of said UICC (56); - permanently disabling the operation of the UICC (56); and - Storing characteristic measurements of the host ME (4).

33. A UICC (56) according to any one of claims 24 to 32, wherein: The UICC (56) is further configured to: If the characteristic measurement value of the host ME (4) is consistent with the first ME fingerprint, a second action is performed.

34. The UICC (56) according to claim 33, wherein: The second action includes any one or more of the following: - providing the host ME (4) with information required for the host ME (4) to register and / or authenticate with the network; - unlocking the functionality of the UICC (56); - providing authentication information of a primary subscription stored on said UICC (56); - providing a hidden identifier to said host ME (4); as well as - Provide a Subscription Hidden Identifier SUCI to the host ME (4).

35. A universal integrated circuit card UICC (56) for a first mobile equipment ME, the UICC (56) being configured to: measuring one or more characteristics of the first ME; and A first ME fingerprint of the first ME is determined based on the characteristic measurements.

36. The UICC (56) according to claim 35, wherein: The first ME fingerprint comprises one or more statistical values, and wherein the UICC (56) is configured to determine the first ME fingerprint by analyzing characteristic measurements of the first ME to determine the one or more statistical values ​​representative of the first ME.

37. The UICC (56) according to claim 36, wherein: The one or more statistical values ​​include mean and / or variance information of the one or more characteristics.

38. The UICC (56) according to claim 35, wherein: The first ME fingerprint comprises one or more model weights of a machine learning (ML) model, and wherein the UICC (56) is configured to determine the first ME fingerprint by training or updating the ML model using characteristic measurements of the first ME, such that the trained or updated ML model is capable of providing an output indicating whether the characteristic measurements input to the ML model are consistent with the first ME, and determining the first ME fingerprint as one or more model weights of the trained or updated ML model.

39. One or more network nodes (1300) for a network (8), the one or more network nodes (1300) being configured to: receiving a first message from a host mobile device ME (4) which is registering and / or authenticating with a network (8) or has registered and / or authenticated with the network (8); processing the first message to extract an indication of whether a Universal Integrated Circuit Card (UICC) (56) in the host ME (4) considers a characteristic measurement of the host ME (4) to be consistent with a first ME fingerprint corresponding to a first ME; and An action is performed based on the extracted indication.

40. The one or more network nodes (1300) of claim 39, wherein: The first message is a hidden identifier or a subscription hidden identifier SUCI, or includes a hidden identifier or SUCI.

41. The one or more network nodes (1300) of claim 40, wherein: The extracted indication comprises information encoded in the hidden identifier or the SUCI indicating whether the characteristics of the host ME (4) are consistent with the first ME fingerprint.

42. The one or more network nodes (1300) of claim 39, wherein: The first message is or includes information encrypted using an over-the-air OTA key previously provided by the network to the UICC (56).

43. The one or more network nodes (1300) of claim 39, wherein: The first message is a Short Message Service SMS message.

44. One or more network nodes (1300) according to any one of claims 39 to 43, wherein: The one or more network nodes (8) are configured to, if the indication indicates that the UICC (56) considers that the characteristic measurement value of the host ME (4) is inconsistent with a first ME fingerprint corresponding to the first ME, perform one or more of the following: blocking or preventing the host ME (4) from accessing the network (8); reducing or limiting the services provided by the network (8) to the host ME (4); as well as A second message is sent to a subscriber associated with the UICC (56) to query for inconsistencies.

45. A universal integrated circuit card UICC (56) for a mobile equipment ME (4), the UICC (56) comprising: a control unit (24) configured to control the operation of the UICC (56); an interface circuit (20; 22) coupled to the control unit (24), wherein the interface circuit (20; 22) is configured to be connected to a corresponding interface circuit (16) in the ME (4) so ​​as to enable the exchange of electrical signals with the ME (4); as well as One or more probe assemblies (60) are coupled to the interface circuit (20; 22) and are configured to measure characteristics of electrical signals received from the ME (4) via the interface circuit (20; 22).

46. ​​The UICC (56) according to claim 45, wherein: The characteristic comprises any one of the following: an electrical parameter of the electrical signal, a voltage parameter of the electrical signal, a communication parameter of the electrical signal, a signal level of the electrical signal, a duty cycle length of the electrical signal, one or more parameters of a clock signal provided by an ME carrying the UICC (56) to the UICC (56), and one or more electrical parameters of a logic signal.

47. The UICC (56) according to claim 45 or 46, wherein: The UICC (56) is further configured to perform a method according to any one of claims 1 to 16.

48. A universal integrated circuit card UICC for a host mobile equipment ME, wherein: The UICC comprises a processor and a memory, the memory containing instructions executable by the processor, whereby the UICC is operable to: measuring one or more characteristics of the host ME; determining whether a characteristic measurement value of the host ME is consistent with a first ME fingerprint corresponding to a first ME; as well as If the characteristic measurement value of the host ME is inconsistent with the first ME fingerprint, a first action is performed.

49. The UICC according to claim 48, wherein: The one or more characteristics include any one or more of the following: Electrical parameters, voltage parameters, communication parameters, signal levels, duty cycle length, one or more parameters of a clock signal provided by the ME carrying the UICC to the UICC, one or more electrical parameters of a logic signal, one or more parameters related to a data link protocol, one or more parameters related to a transport protocol, one or more parameters related to an application selection protocol, an order of accessing directories and / or files in a UICC main directory, an order of accessing directories and / or files in a Universal Subscriber Identity Module (USIM) application directory, an order of commands issued by the ME carrying the UICC, command parameters and / or command timing information.

50. The UICC according to claim 48 or 49, wherein: The characteristics are measured by one or more probes in the UICC.

51. A UICC according to any one of claims 48 to 50, wherein: The UICC is configured to measure the one or more characteristics in any one or more of the following situations: - when the UICC is initialized in the host ME; - continuously or periodically during the operation of the UICC in said host ME; - before or during a network registration process in which the host ME is to register with the network; - before using a user code to unlock the functionality of the UICC in the host ME; - when the host ME requests hiding of the identifier; - when authentication is requested from the UICC; and - When the host ME requests to subscribe to a hidden identifier SUCI.

52. A UICC according to any one of claims 48 to 51, wherein: The first ME fingerprint is derived from measurements of one or more characteristics of the first ME.

53. A UICC according to any one of claims 48 to 52, wherein: The first ME fingerprint comprises one or more statistical values, and wherein the UICC is configured to determine whether the characteristic measurement values ​​of the host ME are consistent with the first ME fingerprint by comparing the characteristic measurement values ​​of the host ME and / or one or more statistical values ​​derived from the characteristic measurement values ​​of the host ME with the statistical values ​​included in the first ME fingerprint.

54. A UICC according to any one of claims 48 to 52, wherein: The first ME fingerprint comprises one or more model weights of a machine learning ML model, and wherein the UICC is configured to determine whether a characteristic measurement value of the host ME is consistent with the first ME fingerprint by: inputting the characteristic measurement value of the host UE into the ML model configured according to the one or more model weights, and determining whether the characteristic measurement value of the host ME is consistent with the first ME fingerprint based on an output of the ML model.

55. A UICC according to any one of claims 48 to 54, wherein: The UICC is further configured to: When the UICC is mounted in the first ME, measuring one or more characteristics of the first ME; and A first ME fingerprint of the first ME is determined based on measured characteristics of the first ME.

56. A UICC according to any one of claims 48 to 55, wherein: Performing the first action includes any one or more of the following: - avoiding providing the host ME with information required for the host ME to register and / or authenticate with the network; - reject any user code entered into said host ME that would unlock the functionality of the UICC in said host ME; - Activate UICC lock mode; - activating the UICC lock mode and deleting or resetting the first ME fingerprint; - avoid providing hidden identifiers to the host ME; - avoid providing the Subscription Hidden Identifier SUCI to the host ME; - providing the host ME with a modified hidden identifier to be sent to a home network, wherein the modified hidden identifier is derived from an identifier of a subscription associated with the UICC and information indicating that a characteristic measurement of the host ME is inconsistent with the first ME fingerprint; - providing the host ME with a modified SUCI to be sent to a home network, wherein the modified SUCI is derived from a subscription permanent identifier SUPI and information indicating that a characteristic measurement value of the host ME is inconsistent with the first ME fingerprint; - sending a notification to the network that the characteristic measurement value of the host ME is inconsistent with the first ME fingerprint; - Deleting or rewriting subscription information stored in the UICC; - providing authentication information of the secondary subscription stored on the UICC; - temporarily disabling the operation of said UICC; - permanently disable the operation of the UICC; and - Storing characteristic measurements of said host ME.

57. A UICC according to any one of claims 48 to 56, wherein: The UICC is further configured to: If the characteristic measurement value of the host ME is consistent with the first ME fingerprint, a second action is performed.

58. The UICC according to claim 57, wherein: The second action includes any one or more of the following: - providing the host ME with information required for the host ME to register and / or authenticate with the network; - unlocking the functionality of said UICC; - providing authentication information of the primary subscription stored on the UICC; - providing a hidden identifier to said host ME; as well as - Provide a Subscription Hidden Identifier SUCI to the host ME.

59. A universal integrated circuit card UICC for a first mobile equipment ME, wherein: The UICC comprises a processor and a memory, the memory containing instructions executable by the processor, whereby the UICC is operable to: measuring one or more characteristics of the first ME; and A first ME fingerprint of the first ME is determined based on the characteristic measurement value.

60. The UICC according to claim 59, wherein: The first ME fingerprint comprises one or more statistical values, and wherein the UICC is configured to determine the first ME fingerprint by analyzing characteristic measurements of the first ME to determine the one or more statistical values ​​representative of the first ME.

61. The UICC according to claim 60, wherein: The one or more statistical values ​​include mean and / or variance information of the one or more characteristics.

62. The UICC according to claim 59, wherein: The first ME fingerprint comprises one or more model weights of a machine learning (ML) model, and wherein the UICC is configured to determine the first ME fingerprint by: training or updating the ML model using characteristic measurements of the first ME, such that the trained or updated ML model is capable of providing an output indicating whether the characteristic measurements input to the ML model are consistent with the first ME, and determining the first ME fingerprint as one or more model weights of the trained or updated ML model.

63. One or more network nodes for a network, wherein: The one or more network nodes include a processor and a memory, the memory containing instructions executable by the processor, whereby the one or more network nodes are operable to: receiving a first message from a host mobile device ME that is registering and / or authenticating with the network or that has registered and / or authenticated with the network; processing the first message to extract an indication of whether a Universal Integrated Circuit Card UICC in the host ME considers a characteristic measurement value of the host ME to be consistent with a first ME fingerprint corresponding to a first ME; and An action is performed based on the extracted indication.

64. The one or more network nodes of claim 63, wherein: The first message is a hidden identifier or a subscription hidden identifier SUCI, or includes a hidden identifier or SUCI.

65. The one or more network nodes of claim 64, wherein: The extracted indication comprises information encoded in the hidden identifier or the SUCI indicating whether the characteristics of the host ME are consistent with the first ME fingerprint.

66. The one or more network nodes of claim 63, wherein: The first message is information encrypted using an over-the-air OTA key previously provided by the network to the UICC, or includes information encrypted using an OTA key previously provided by the network to the UICC.

67. The one or more network nodes of claim 63, wherein: The first message is a Short Message Service SMS message.

68. One or more network nodes according to any one of claims 63 to 67, wherein: The one or more network nodes are configured to, if the indication indicates that the UICC considers that the characteristic measurement value of the host ME is inconsistent with a first ME fingerprint corresponding to the first ME, perform one or more of the following: Blocking or preventing the host ME from accessing the network; reducing or limiting services provided by said network to said host ME; and A second message is sent to a subscriber associated with the UICC to query for inconsistencies.

69. A universal integrated circuit card UICC for a mobile equipment ME, the UICC comprising: a control unit operable to control the operation of the UICC; an interface circuit coupled to the control unit, wherein the interface circuit is operable to connect to a corresponding interface circuit in the ME to enable exchange of electrical signals with the ME; as well as One or more probe assemblies are coupled to the interface circuit and are operable to measure characteristics of electrical signals received from the ME via the interface circuit.

70. The UICC according to claim 69, wherein: The characteristic includes any one of the following: an electrical parameter of the electrical signal, a voltage parameter of the electrical signal, a communication parameter of the electrical signal, a signal level of the electrical signal, a duty cycle length of the electrical signal, one or more parameters of a clock signal provided by the ME carrying the UICC to the UICC, and one or more electrical parameters of a logic signal.

71. A UICC according to claim 69 or 70, wherein: The UICC comprises a processor and a memory, the memory containing instructions executable by the processor, whereby the UICC is operable to perform a method according to any one of claims 1 to 16.

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