Privacy indicators for controlling authentication requests

Abstract

To provide techniques for providing privacy features in communication systems.SOLUTION: A message with privacy indicators may be provided from user equipment to an element or function in a communication network, where privacy features for processing the message are determined based on the privacy indicators. The message may comprise an attach request comprising a subscription identifier for a subscriber associated with the user equipment. The privacy indicators comprise a flag indicating whether the subscription identifier in the attach request is privacy-protected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application claims priority to U.S. provisional patent application identified as U.S. Serial No. 62 / 502,266, entitled "Privacy Indicator for Controlling Authentication Requests," filed May 5, 2017, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The field relates generally to communication systems, and more particularly, but not exclusively, to security within such systems. [Background technology]

[0003] This section introduces aspects that may be helpful in facilitating a better understanding of the present invention. Accordingly, the statements in this section are to be read in this light and not understood as admissions about what is in the prior art or what is not in the prior art.

[0004] Fourth generation (4G) wireless mobile telecommunications technology, also known as Long Term Evolution (LTE) technology, was designed to provide high-capacity mobile multimedia with high data rates, especially for human interaction. The next generation technology, i.e., fifth generation (5G) technology, is intended to be used not only for human interaction but also for machine-type communication in so-called Internet of Things (IoT) networks.

[0005] 5G networks are intended to enable mass IoT services (e.g., very large numbers of capacity-limited devices) and mission-critical IoT services (e.g., requiring high reliability), while improvements over legacy mobile communication services are supported in the form of enhanced mobile broadband (eMBB) services intended to provide improved wireless internet access to mobile devices.

[0006] In an exemplary communication system, user equipment (5G UE in a 5G network, or more broadly, UE), such as a mobile terminal (subscriber), communicates over the air interface with a base station or access point, referred to as a gNB in ​​a 5G network or an eNB (Evolved Node B) in an LTE network. The access point (e.g., gNB / eNB) is illustratively part of the access network of the communication system. For example, in a 5G network, the access network is referred to as a 5G system and is described in 5G Technical Specification (TS) 23.501, V0.4.0, entitled "Technical Specification Group Services and System Aspects; System Architecture for the 5G System," the disclosure of which is incorporated herein by reference in its entirety. In an LTE network, the access network is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN). Generally, an access point (e.g., gNB / eNB) provides UEs with access to a core network (CN), which in turn provides the UEs with access to other UEs and / or data networks such as packet data networks (e.g., the Internet).

[0007] Privacy is an important consideration in any communication system. Privacy is extensively addressed in 5G Technical Report (TR) 33.899, V1.1.0, entitled "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Study on the security aspects of the next generation system (Release 14)," the disclosure of which is incorporated herein by reference in its entirety. In particular, TR 33.899 identifies subscription (UE) privacy as one of the most important security areas to address in 5G networks. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] 5G Technical Specification (TS) 23.501, V0.4.0, "Technical Specification Group Services and System Aspects; System Architecture for the 5G System" [Non-patent document 2] 5G Technical Report (TR) 33.899, V1.1.0, “3rd Generation Partnership Project;Technical Specification Group Services and System Aspects;Study on the security aspects of the next generation system(Release 14)” [Non-patent document 3] SA2 TS23.305 [Non-patent document 4] 3GPP TS29.272 (Section 8: "User identity to HSS resolution"), "3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Evolved Packet System (EPS); Mobility Management Entity (MME) and Serving GPRS Support Node (SGSN) related interfaces based on Diameter protocol (Release 14)" [Non-Patent Document 5] SA3 TS33.899 Summary of the Invention [Means for solving the problem]

[0009] Exemplary embodiments provide one or more privacy indicators for controlling authentication requests in a communication system.

[0010] For example, in one embodiment, a method comprises, at an element or function in a communications network, receiving a message from user equipment of the communications network, the message comprising one or more privacy indicators, and determining one or more privacy features for processing the message based on the one or more privacy indicators.

[0011] The message may comprise an attach request comprising a subscription identifier for a subscriber of a communications network associated with the user equipment, and the one or more privacy indicators comprise a flag indicating whether the subscription identifier in the attach request is privacy-protected. The privacy-protected subscription identifier may comprise at least a portion of a durable subscription identifier for the subscriber.

[0012] In another embodiment, a method comprises: determining, at an element or function in the communications network, one or more privacy features supported by the communications network; generating, at the element or function in the communications network, a message comprising one or more privacy indicators selected based on the determined one or more privacy features; and transmitting the generated message comprising the one or more privacy indicators from the element or function in the communications network to user equipment of the communications network.

[0013] The one or more privacy features may comprise the ability of elements or functions in a communications network to handle privacy-protected subscription identifiers.

[0014] In another embodiment, a method comprises determining, in user equipment of a communications network, one or more privacy features for processing a message; adding one or more privacy indicators to the message based on the determined one or more privacy features; and transmitting the message with the one or more privacy indicators from the user equipment to an element or function in the communications network.

[0015] The message may comprise an attach request comprising a subscription identifier for a subscriber of a communications network associated with the user equipment, and the one or more privacy indicators comprise a flag indicating whether the subscription identifier in the attach request is privacy protected.

[0016] In another embodiment, a method comprises receiving, at user equipment of a communications network, a message from an element or function in the communications network, the message comprising one or more privacy indicators, and utilizing the one or more privacy indicators to determine one or more privacy features supported by the communications network.

[0017] The one or more privacy indicators may comprise an indication of whether the communications network is configured to handle privacy-protected subscription identifiers. The method may further include refraining from sending an attach request to an element or function in the communications network in response to the one or more privacy indicators indicating that the communications network is not configured to handle privacy-protected subscription identifiers.

[0018] These and other techniques described herein may be applied to a variety of communication networks, but they are particularly well suited to 5G and next generation communication networks.

[0019] These and other features and advantages of the embodiments described herein will become more apparent from the accompanying drawings and the following detailed description. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 illustrates a communication system in an exemplary embodiment. [Figure 2] FIG. 2 illustrates the server location function and home subscriber server in more detail in an exemplary embodiment. [Figure 3] FIG. 1 illustrates a message flow for a user equipment authentication procedure for an LTE network in an exemplary embodiment. [Figure 4] FIG. 1 illustrates a message flow for a user equipment authentication procedure for a 5G network in an exemplary embodiment. [Figure 5] FIG. 1 illustrates a message flow for a user equipment authentication procedure for a hybrid LTE / 5G network in an exemplary embodiment. [Figure 6] FIG. 10 illustrates a message flow for a user equipment authentication procedure for a 5G network in another exemplary embodiment. [Figure 7] FIG. 1 illustrates a message flow for user equipment accessing a 5G network via non-3GPP access and authentication in an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Embodiments are illustrated herein in conjunction with exemplary communication systems and associated techniques for managing authentication requests in a manner that protects the privacy of a user's subscription identification. However, it should be understood that the claims are not limited to the particular types of communication systems and / or processes disclosed. The embodiments can be implemented in a wide variety of other types of communication systems using alternative processes and operations. While illustrated in the context of a wireless cellular system utilizing 3GPP system elements, such as the LTE Evolved Packet Core (EPC) and 3GPP Next Generation System (5G), the disclosed embodiments can be straightforwardly adapted to various other types of communication systems, including, but not limited to, WiMAX and Wi-Fi systems.

[0022] As mentioned above, privacy of subscription identifiers when communicating over the air interface between user equipment and network access points was a significant issue for 2G / 3G / 4G networks. Efforts have been made to address this important issue in 5G networks. It is recognized that there is a need to address these privacy requirements even if it is inevitable that a down bidding attack (e.g., an attacker masquerading as user equipment so as to negotiate inferior security capabilities with a network access point) could force a 5G UE to attach to a lower generation network.

[0023] The above-referenced TR33.899 describes several solutions for providing privacy over the air interface, which it classifies into three classes of solutions: 1) A pseudonym solution based on a symmetric cryptosystem, which requires the home subscriber server / function of the UE's home network to map a changing pseudonym to the UE's persistent subscription identifier; 2) Encrypting the UE's persistent subscription identifier using the home network operator's public key; and 3) Encrypting the UE's persistent subscription identifier using the serving network operator's public key. These can be generally grouped into:

[0024] Note that in one example, the International Mobile Subscriber Identity (IMSI) is the UE's persistent subscription identifier (subscriber identity). In one embodiment, the IMSI is a fixed 15-digit length, consisting of a 3-digit Mobile Country Code (MCC), a 3-digit Mobile Network Code (MNC), and a 9-digit Mobile Station Identification Number (MSIN).

[0025] It should also be noted that in LTE networks the home subscriber server / function is called the Home Subscriber Server (HSS), and in 5G networks it is called the User Data Management (UDM), which may comprise an Authentication and Security Function (AUSF) and an Authentication Credential Repository and Processing Function (ARPF) as part of the UDM function.

[0026] Although some example embodiments are described herein in terms of the second solution class (i.e., home network public key-based solutions), alternative embodiments may be implemented with respect to the other two solution classes. See SA2 TS23.502 and SA3 TS33.899, the disclosures of which are incorporated herein by reference in their entireties.

[0027] In a home network public key-based solution, the home operator provides its public key to all home network subscribers. The home network subscriber uses it to encrypt the subscriber identity, which is, for example, the MSIN portion of the IMSI. Because the MNC+MCC is required by the serving network to route to the correct home network, only the MSIN portion needs to be encrypted. Only the home HSS can decrypt the message because it possesses the private key corresponding to the public key. Once the IMSI is identified, the HSS / AuC (where the AuC is the authentication center portion of the HSS) will create an authentication vector (AV) based on a separate shared root key K between the user (subscriber) and the HSS / AuC. Similarly, in 5G networks, the UDM / ARPF creates the requested AV via the AUSF. The AUSF and UDM may be collocated for optimization reasons.

[0028] An operator may have multiple HSS implementations in his network, allowing him to manage separate sets of users in different HSS / UDMs. For multiple HSSs, a Server Location Function (SLF) may be implemented in front of the set of HSSs. Note that the SLF may also be called a Subscriber Location Function. The SLF analyzes authentication requests for users received from the MME / AMF and routes them to the correct HSS.

[0029] By way of example only, the operation of the SLF is described in 3GPP TS 29.272 (Section 8: "User identity to HSS resolution"), entitled "3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Evolved Packet System (EPS); Mobility Management Entity (MME) and Serving GPRS Support Node (SGSN) related interfaces based on Diameter protocol (Release 14)," the disclosure of which is incorporated herein by reference in its entirety. The SLF provides user identity (IMSI)-to-HSS resolution using a locally maintained subscriber profile database and routes Diameter messages containing user authentication requests as a Diameter proxy to the selected HSS. Note that in 5G, if the 5G core network protocol is different from Diameter, similar functionality, such as using an http proxy, is still required. In the following description, SLF is assumed to cover both 4G DRA (Diameter Routing Agent) based solutions or any other proxy related solutions, depending on the protocol decisions regarding the 5G core network.

[0030] It is recognized herein that if a home operator uses an SLF to split a set of subscribers, the SLF must first evaluate the received identifier. Thus, in a 5G network where persistent subscriber identities (e.g., IMSIs) are encrypted by one of the methods, the SLF will need to take over decryption of the MSIN portion of the IMSI. Furthermore, the SLF will need to maintain a database of all subscriber profiles along with routing information, i.e., the profile must map the subscriber's persistent identity (e.g., IMSI) to one of the HSSs in the network and forward the authentication request after decrypting the received (encrypted) IMSI. Therefore, it is advantageous to perform decryption of the encrypted IMSI in the SLF instead of in the HSS. Therefore, instead of the HSS storing the private key, the SLF now needs to store and use the network private key. The SLF is located in the home operator's domain and is considered trusted. Generally, an SLF can be envisioned in large operator networks. The use of the SLF simplifies the new privacy management for the HSS / UDM in 5G networks to the point where the HSS / UDM is never modified to protect the subscription identifier over the air interface, but the SLF still needs to perform the additional functions of encrypted IMSI decryption and subsequent IMSI-to-HSS resolution.

[0031] Therefore, the exemplary embodiments described herein address the problem of how the HSS / UDM or SLF can efficiently handle the newly introduced privacy feature, namely, that the received attach request needs to be decrypted first. If this is not taken care of, the HSS / UDM or SLF will receive the request and try to process it, wasting useless computational resources.

[0032] Privacy depends on country-specific regulations and therefore the HSS / UDM or SLF needs to be implemented to handle both cases of requests for authentication vectors, i.e. to process or forward a "normal" attach request if the 5G UE does not apply privacy, or to process a "privacy" attach request.

[0033] In a first exemplary embodiment, if the 5G UE wishes to protect its privacy, it adds an identification privacy flag (i.e., a privacy indicator) to indicate that the MSIN is provided in encrypted form.

[0034] It should be understood that in addition to being an “explicit” privacy indicator, such as a flag or field, the privacy indicator can alternatively be an “implicit” privacy indicator. By implicit privacy indicator, it is meant that the privacy feature is conveyed by the UE to the network element / function via the algorithm used to encrypt the message. Thus, the network element / function receiving the message from the UE is informed of the privacy feature by the fact that the message is encrypted with a particular encryption algorithm. This also applies to a NULL encryption scheme, in which the input equals the output and the SUPI (Subscription Permanent Identifier of the UE) is not encrypted, i.e., format-preserving. This can also be interpreted as the SUPI (or IMSI) being encrypted all the time, but if privacy is not “turned on” at all, NULL encryption is used. Thus, the privacy indicator is implicit in the algorithm scheme used (e.g., NULL encryption or the algorithm that actually encrypts the message).

[0035] It may be suggested that the HSS or SLF would resolve the request even without this privacy indicator and would have an idea after the first attempt to decrypt if it was encrypted. However, one important reason for making such an indication explicit is that it saves processing time and requires fewer processing resources. Thus, in this first exemplary embodiment, the SLF can make processing decisions by looking at this flag. If it is not set, the SLF assumes that the provided IMSI is unencrypted and performs IMSI-to-HSS resolution and forwards it to the correct HSS / UDM, i.e., compatibility with 4G operation is preserved. If the flag is set, the SLF recognizes that the provided IMSI is encrypted, decrypts the MSIN portion using the network secret key to form the true unencrypted IMSI, performs IMSI-to-HSS resolution, and then forwards the authentication request to the correct HSS / UDM. If an SLF is not used, the same principle can be used by the HSS / UDM. That is, the HSS / UDM must check whether the 5G UE has set the flag and then decide whether decoding is required.

[0036] This first exemplary embodiment can be applied to a 5G UE that attaches to a 5G Core Network (CN) via a 5G RAN (Radio Access Network). However, 3GPP has identified that the 5G UE should attach to a 4G CN via a 5G RAN as the immediate deployment scenario. If the UE sets the indicator, the 4G CN will need to be enhanced to understand the identity privacy flag or other privacy indicator.

[0037] From the perspective of network architecture for operators with evolving 4G networks to 5G, both 4G and 5G access and core networks need to be supported for a considerable time. This means that the current 4G HSS needs to be supported while supporting a new 5G HSS function that decrypts the encrypted MSIN. According to an embodiment, identifying the encrypted MSIN before routing the authentication request to the HSS and having an SLF that can decrypt it helps manage the coexistence of 4G and 5G core in an operator network. Enhancing the SLF to support the new identification 5G privacy feature is more advantageous than enhancing the HSS. When the HSS is enhanced, in a large network with multiple HSSs, all HSSs need to be updated with the ability to decrypt the encrypted IMSI. This can be more cumbersome to handle compared to solving the problem at a single central node (e.g., the SLF). Advantageously, in the first exemplary embodiment, a bidding-down attack in 5G (to 4G) will not be beneficial if the same feature is also deployed in 4G, whereby an enhanced SLF is used to realize this feature.

[0038] In a second exemplary embodiment, another privacy indicator is provided that an operator can decide to add to a network master information block (MIB) / system information block (SIB) broadcast, for example, a flag indicating that privacy is expected, can be handled, or is desired, to indicate to a 5G UE that the network can handle privacy-protected identifiers. If this indicator is not sent, then, whether to attach to the network at all is left to the policy implemented / configured by the 5G UE. The indicator on the 4G / 5G network side will indicate the regulatory needs of each country / region, i.e., privacy on / off. While the UE is roaming in the target network, the UE authentication request from the target network is forwarded to the home network, and although an identity privacy indicator for this (the first exemplary embodiment above) has been described, it should be noted that there is also a need to adapt it to the serving network. The MME / SEAF (SEAF is the Security Anchor Function) must handle the enhanced initial attach message from the UE, form a UE Authentication Request message, and route it to the home network to request AV. If the subscription identifier is encrypted, the size of the message field for the encrypted IMSI may be different from today's 4G IMSI field (depending on the chosen solution class).

[0039] Note that the target network may also indicate its availability and, if applicable, that it does not use privacy. This information may be broadcast, for example, as part of a SIB or other information block, or may be sent as an explicit request message to each UE.

[0040] In a third exemplary embodiment, the UE is configured to manage a privacy indicator that can be set to prohibit the 5G UE from responding to IMSI paging, such that when the UE wishes to attach to a network and the network requests the UE's true identity, a privacy-configured 5G UE configured with this privacy indicator will not reply.

[0041] Given the privacy indicators described above, a wide variety of network configurations can be employed to implement the privacy indicators. FIGS. 1-7 depict some of these network configurations. However, it should be appreciated that the embodiments are not limited to the network configurations illustrated herein or otherwise described below. FIG. 1 depicts a communication system 100 in which exemplary embodiments are implemented. It should be understood that the elements depicted in communication system 100 are intended to represent key functions provided within the system, e.g., UE access functions, mobility management functions, serving gateway functions, etc. As such, the blocks depicted in FIG. 1 refer to specific elements in LTE and 5G networks that provide the key functions. However, other network elements may be used to implement some or all of the key functions depicted. It should also be understood that not all functionality of an LTE or 5G network is depicted in FIG. 1 . Rather, functionality that facilitates explanation of the exemplary embodiments is depicted.

[0042] Thus, as shown, communication system 100 comprises user equipment (UE) 102 that communicates with access point (eNB / gNB) 104 via air interface 103. UE 102 may be a mobile station, which may comprise, by way of example, a mobile phone, a computer, or any other type of communication device. In an LTE-V2X implementation, one or more UEs may be deployed in a given vehicle. Thus, as used herein, the term “user equipment” is intended to be broadly interpreted to encompass communication devices, including examples such as a combination of various different types of mobile stations, subscriber stations, or, more generally, a data card inserted into a laptop or other device (e.g., a vehicle). Such communication devices are also intended to encompass devices commonly referred to as access terminals.

[0043] In one embodiment, the UE 102 consists of a Universal Integrated Circuit Card (UICC) and a Mobile Equipment (ME). The UICC is the user-dependent part of the UE and contains at least one Universal Subscriber Identity Module (USIM) and appropriate application software. The USIM securely stores the International Mobile Subscriber Identity (IMSI) number and keys associated with the IMSI, which are used to identify and authenticate subscribers accessing the network. The ME is the user-independent part of the UE and contains the Terminal Equipment (TE) functions and various Mobile Termination (MT) functions.

[0044] The access point 104 is illustratively part of an access network of the communication system 100. Such an access network may comprise, for example, an E-UTRAN or 5G system (or a hybrid) having multiple base stations and one or more associated radio network control functions. The base stations and radio network control functions may be logically separate entities, but in a given embodiment may be implemented in the same physical network element, such as, for example, a base station router or a femtocellular access point.

[0045] The access point 104 in this exemplary embodiment is operatively coupled to a mobility management function 106. In LTE networks, this function is typically implemented by a mobility management element (MME), while in 5G networks, this function is implemented by an access and mobility management function (AMF). Although not explicitly shown, the SEAF may be implemented using the AMF, which connects the UE with mobility management. As used herein, a mobility management function is an element or function in the CN portion of a communication system that manages access and authentication operations with the UE (through the access point 104), among other network operations.

[0046] The MME / AMF 106 in this exemplary embodiment is operably coupled to the SLF 107. In the exemplary embodiment, the SLF 107 is configured, as described above, to respond to one or more privacy indicators set in messages that the SLF 107 receives. As described above, the SLF 107 may decrypt the subscriber identity or simply forward the encrypted information to the appropriate home network of the UE 102, depending on the one or more privacy indicators. Thus, as shown, the SLF 107 is operably coupled to multiple HSS / UDMs 108-1, 108-2, ..., 108-N. These HSS / UDMs represent home networks of UEs that may attach to the communication system 100. The SLF 107 is configured to provide UE information to the appropriate HSS / UDM 108.

[0047] The access point 104 is also operatively coupled to a Serving Gateway Function 110 (e.g., a Serving Gateway (SGW) in an LTE network and a Session Management Function (SMF) in a 5G network), which is operatively coupled to a Packet Data Network (PDN) Gateway (PGW) 112. The PGW 112 is operatively coupled to a packet data network, e.g., the Internet 114. The MME / AMF 106 and the SLF 107 may be considered to be part of the CN. The MME / AMF 106 and the SLF 107 may also be part of a serving network. Further typical operation and functionality of such network elements will not be described here, as they are not the focus of the exemplary embodiments and may be found in appropriate 3GPP LTE or 5G literature.

[0048] It should be appreciated that this particular arrangement of system elements is merely exemplary, and that additional or alternative elements of other types and arrangements may be used to implement a communication system in other embodiments. For example, in other embodiments, system 100 may include authentication elements and other elements not expressly shown herein.

[0049] 1 is merely one exemplary arrangement of a wireless cellular system, and many alternative configurations of system elements may be used. For example, while only a single UE, eNB / gNB, MME / AMF, SLF, SGW / SMF, and PGW elements are shown in the embodiment of FIG. 1, this is for clarity of explanation only. A given alternative embodiment may, of course, include a greater number of such system elements, as well as additional or alternative elements of the type typically associated with conventional system implementations.

[0050] Also, while FIG. 1 illustrates system elements as single functional blocks, it should be noted that the various subnetworks that make up the 5G network are divided into so-called network slices. A network slice (network partition) comprises a set of functions (i.e., a function chain) for each corresponding service type using network function virtualization (NVF) on a common physical infrastructure. A network slice is instantiated as needed for a given service, e.g., eMBB service, large-scale IoT service (e.g., V2X service), and mission-critical IoT service. Thus, a network slice or function is instantiated when an instance of that network slice or network function is created. In some embodiments, this involves installing or otherwise running the network slice or function on one or more host devices of the underlying physical infrastructure. The UE 102 is configured to access one or more of these services via the eNB / gNB 104.

[0051] FIG. 2 shows a more detailed diagram of the SLF 107 and one HSS / UDM 108 in an example embodiment. Each HSS / UDM 108 (108-1, 108-2, ..., 108-N) in FIG. 1 can be configured as shown in FIG. 2. The SLF 107 comprises a processor 200 coupled to a memory 202 and an interface circuit 204. The processor 200 of the SLF 107 includes an authentication processing module 210, which may be implemented at least partially in the form of software executed by the processor 200. The authentication processing module 210 performs authentication operations of the processes described in conjunction with subsequent figures and otherwise described herein. The memory 202 of the SLF 107 includes an authentication storage module 212 that stores authentications and associated data generated or otherwise used during authentication operations.

[0052] The HSS / UDM 108 comprises a processor 220 coupled to a memory 222 and an interface circuit 224. The processor 220 of the HSS / UDM 108 includes an authentication processing module 230 that may be implemented at least in part in software executed by the processor 220. The authentication processing module 230 performs the authentication operations of the processes described in conjunction with subsequent figures and otherwise described herein. The memory 222 of the HSS / UDM 108 includes an authentication storage module 232 that stores authentication data and related data generated or otherwise used during authentication operations.

[0053] The processors 200 and 220 of the SLF 107 and HSS / UDM 108, respectively, may comprise, for example, a microprocessor, an application specific integrated circuit (ASIC), a digital signal processor (DSP), or other type of processing device, and portions or combinations of such elements.

[0054] The memories 202 and 222 of the SLF 107 and HSS / UDM 108, respectively, may be used to store one or more software programs that are executed by the processors 200 and 220, respectively, to implement at least a portion of the functionality described herein. For example, authentication operations and other functions described in conjunction with the subsequent figures and otherwise described herein may be implemented in a straightforward manner using software code executed by the processors 200 and 220.

[0055] Thus, a given one of memories 202 or 222 may be considered an example of what is referred to herein more generally as a computer program product or, even more generally, as a processor-readable storage medium having executable program code embodied therein. Other examples of processor-readable storage media may include disks or other types of magnetic or optical media, in any combination. Example embodiments may include articles of manufacture comprising such computer program products or other processor-readable storage media.

[0056] Memory 202 or 222 may, more particularly, comprise electronic random access memory (RAM), such as, for example, static RAM (SRAM), dynamic RAM (DRAM), or other types of volatile or non-volatile electronic memory. The latter may include, for example, non-volatile memory, such as flash memory, magnetic RAM (MRAM), phase-change RAM (PC-RAM), or ferroelectric RAM (FRAM). As used herein, the term "memory" is intended to be interpreted broadly and may additionally or alternatively encompass, for example, read-only memory (ROM), disk-based memory, or other types of storage devices, and portions or combinations of such devices.

[0057] The interface circuits 204 and 224 of the SLF 107 and HSS / UDM 108, respectively, illustratively comprise transceivers or other communications hardware or firmware that enable the associated system elements to communicate with each other in the manner described herein.

[0058] It is apparent from FIG. 2 that the SLF 107 is configured for communication with the HSS / UDM 108 and vice versa via interface circuits 204 and 224, respectively. This communication involves the SLF 107 transmitting data to the HSS / UDM 108, and the HSS / UDM 108 transmitting data to the SLF 107. However, in alternative embodiments, other network elements may be operatively coupled between the SLF and the HSS / UDM. As used herein, the term “data” is intended to be broadly interpreted to encompass any type of information that may be transmitted between user equipment and the core network via base station elements, including, but not limited to, identification data, authentication data, control data, audio, video, multimedia, etc.

[0059] It should be appreciated that the particular arrangement of components shown in Figure 2 is exemplary only, and that many alternative configurations may be used in other embodiments. For example, the user equipment and mobility management functions may be configured to incorporate additional or alternative components and to support other communication protocols.

[0060] Other system elements, such as the UE 102, eNB / gNB 104, MME / AMF 106, SGW / SMF 110, and PGW 112, may also each be configured to include components such as a processor, memory, and network interfaces. These elements need not be implemented on separate, standalone processing platforms but may instead represent, for example, different functional portions of a single, common processing platform. Such a processing platform may further comprise at least a portion of an eNB / gNB and associated radio network control functionality.

[0061] 3-7 illustrate example message flows and network configurations in which one or more of the above-described privacy indicators may be implemented, and it is understood that these message flows and network configurations are exemplary embodiments.

[0062] FIG. 3 illustrates a high-level UE authentication procedure 300 in LTE using unencrypted IMSI, SLF, and multiple HSSs, according to one example embodiment.

[0063] In more detail, Figure 3 shows a UE 302, a RAN 304, an MME 306, an SLF 308, HSS1 310-1, and HSS2 310-2. Although only two HSSs are depicted, any number of HSSs may be implemented according to embodiments described herein. In step 1 of the UE authentication procedure flow of Figure 3, the UE 302 sends an attach request (IMSI) to the MME 306 through the RAN 304. In step 2, the MME 306 then sends an authentication request (IMSI) to the SLF 308. In step 3, the SLF 308 selects an HSS based on the IMSI-to-HSS mapping. In step 4, the SLF 308 sends the authentication request (IMSI) to the selected HSS, which is HSS1 310-1, as indicated in Figure 3. In step 5, HSS1 310-1 generates an authentication vector (AV) based on a root key. In step 6, the HSS1 310-1 sends an authentication response (AV) to the SLF 308, and in step 7, the SLF 308 sends the authentication response (AV) to the MME 306. The authentication response may comprise a random challenge (RAND), an authentication token (AUTN), and a keyset identifier (KSI). In step 9, the MME 306 sends an attach response to the UE 302 through the RAN 304.

[0064] 4 illustrates a high-level UE authentication procedure 400 in 5G using encrypted IMSI, SLF, and multiple UDMs. Performing IMSI decryption in the SLF instead of the UDM helps to keep the core authentication functionality unchanged, according to one example embodiment. As used herein, the acronym EAP refers to Extensible Authentication Protocol, and the acronym AKA refers to Authentication and Key Agreement.

[0065] In more detail, FIG. 4 shows a UE 402, an (R)AN 404, an AMF 406, an SLF 408, an AUSF / UDM 410-1, and an AUSF / UDM 410-2. Although only two AUSF / UDMs are depicted, any number of AUSF / UDMs may be implemented according to embodiments described herein. In step 1 of the UE authentication procedure flow of FIG. 4, the UE 402 sends a registration request (encrypted IMSI) to the AMF 406 through the (R)AN 404. Note that by referring to an encrypted IMSI, this may generally refer to a portion of the IMSI that is encrypted, such as the MSIN, or all or some other portion of the IMSI. In step 2, the AMF 406 sends the authentication request (encrypted IMSI) to the SLF 408. Step 3 includes sub-steps 3a and 3b. In step 3a, the SLF 408 decrypts the encrypted IMSI. In one embodiment, the SLF 408 decrypts the encrypted IMSI using the provisioned certificate. In step 3b, the SLF 408 selects an HSS based on the IMSI to UDM mapping. In step 4, the SLF 408 sends an authentication request (IMSI) to the selected UDM, which is the AUSF / UDM 410-1, as indicated in FIG. 4. In step 5, the AUSF / UDM 410-1 generates an authentication vector (AV) based on the root key. In step 6, the AUSF / UDM 410-1 performs EAP AKA' authentication or EAP AKA * Authentication (AKA * refers to AKA with greater home control). In step 7, the AUSF / UDM 410-1 sends an authentication response (AV) to the SLF 408, and in step 8, the SLF 408 sends the authentication response (AV) to the AMF 406. In step 9, the AMF 406 sends an authentication request to the UE 402 through the (R)AN 404.

[0066] 5 illustrates a procedure 500 for a hybrid UDM and HSS core architecture supporting 4G LTE and 5G networks, according to one example embodiment. IMSI decoding in the SLF serves to manage both cores.

[0067] 5 shows a UE 502, a gNB 504, an AMF / MME 506, an SLF 508, an AUSF / UDMs 510-1 and 510-2, and an HSS 512. Although only two AUSF / UDMs are depicted, any number of AUSF / UDMs may be implemented according to embodiments described herein.

[0068] In step 1 of the procedure of FIG. 5, the UE 502 sends an attach request (encrypted IMSI) to the AMF / MME 506 through the gNB 504. Note that by referring to the encrypted IMSI, this can generally refer to the portion of the IMSI that is encrypted, e.g., the MSIN, or all or some other portion of the IMSI. Next, in step 2, the AMF / MME 506 sends an authentication request (encrypted IMSI) to the SLF 508. Step 3 includes sub-steps 3a and 3b. In step 3a, the SLF 508 decrypts the encrypted IMSI. In one embodiment, the SLF 508 decrypts the encrypted IMSI using a provisioned certificate. In step 3b, the SLF 508 selects an HSS based on the IMSI-to-HSS mapping. In step 4, the SLF 508 sends the authentication request (IMSI) to the selected HSS, HSS 512, through the AUSF / UDMs 510-1 and 510-2. In step 5, the HSS 512 generates an authentication vector (AV) based on the root key. In step 6, the HSS 512 sends the authentication response (AV) to the SLF 508 through the AUSF / UDMs 510-1 and 510-2, and in step 7, the SLF 508 sends the authentication response (AV) to the AMF / MME 506. In step 8, the AMF / MME 506 sends an attach response to the UE 502 through the gNB 504.

[0069] 6 illustrates a high-level UE authentication procedure 600 in 5G using encrypted IMSI, SLF, and multiple UDMs, according to an example embodiment. Performing IMSI decryption in the SLF instead of the UDM helps to keep the core authentication functionality unchanged.

[0070] In more detail, FIG. 6 shows a UE 602, an (R)AN 604, an AMF 606, an AUSF 608, an SLF 610, and UDMs 612-1 and 612-2. Although only two UDMs are depicted, any number of UDMs may be implemented according to embodiments described herein. In step 1 of the high-level UE authentication procedure flow of FIG. 6, the UE 602 sends a registration request (encrypted IMSI) to the AMF 606 through the (R)AN 604. Note that by referring to an encrypted IMSI, this may generally refer to the portion of the IMSI that is encrypted, e.g., the MSIN, or all or some other portion of the IMSI. Next, in step 2, the AMF 606 sends an authentication request (encrypted IMSI) to the AUSF 608. In step 3, the AUSF 608 sends the authentication request (encrypted IMSI) to the SLF 610. In step 3a, the SLF 610 decrypts the encrypted IMSI. In one embodiment, the SLF 610 decrypts the encrypted IMSI using the provisioned certificate. In step 3b, the SLF 610 selects an HSS based on the IMSI to UDM mapping. In step 4, the SLF 610 sends an authentication request (IMSI) to the selected UDM, which is UDM 612-1 as shown in FIG. 6. In step 5, the UDM 612-1 generates an authentication vector (AV) based on the root key. In step 6, the UDM 612-1 sends an authentication response (AV) to the SLF 610, and in step 7, the SLF 610 sends the authentication response (AV) to the AUSF 608. In step 8, the AUSF 608 performs EAP AKA' authentication or EAP AKA authentication. *In step 9, the AUSF 608 sends an authentication response to the AMF 606. In step 10, the AMF 606 sends an authentication request to the UE 602 through the (R)AN 604.

[0071] 7 illustrates a procedure 700 for a UE accessing a 5G network via non-3GPP access (WLAN) and authentication, according to an example embodiment. As used herein, the acronym AN refers to Access Network, the acronym NAI refers to Network Access Identifier, and the acronym SUPI refers to UE Serialized Unique Product Identifier.

[0072] In more detail, FIG. 7 shows a UE 702, a non-3GPP AN 704, an AMF 706, an AUSF 708, and a UDM 710. In step 1 of the procedure in FIG. 7, the UE 702 sends a registration request to the AMF 706 through the non-3GPP AN 704. In step 2, the AMF 706 sends an authentication request (NAI, [EAP]) to the AUSF 708. The AUSF 708 selects an authentication type (e.g., EAP AKA authentication or EAP AKA authentication). * Authentication) and acts as the EAP server to determine whether EAP AKA authentication or EAP AKA * UE 702 performs authentication. In step 3, security material is retrieved from UDM 710 based on the NAI. In step 4, AUSF 708 sends an authentication response ([EAP]) to AMF 706, which initiates UE authentication in step 5. As shown, during UE authentication, AMF 706 sends an authentication request (SUPI, [EAP]) to AUSF 708. Depending on the EAP authentication method chosen, several authentication request messages may be required between UE 702 and AUSF 708 (via AMF 706). If UE authentication is successful, AUSF 708 sends an authentication response ([EAP], Key) to AMF 706. Key is a security key that may be used by AMF 706 to generate non-access stratum (NAS), control plane (CP), and user plane (UP) specific security keys.

[0073] The techniques described herein provide one or more privacy indicators for authentication requests in a communication system. For example, such privacy indicators can be controlled (e.g., set) by using one or more bits in an information element or flag transmitted to an element of the communication system. Furthermore, methods and mechanisms are provided that address how other elements / functions (e.g., server location functions) in the user equipment's home network and core network can efficiently process the one or more privacy indicators. Advantageously, the one or more privacy indicators conserve computing resources that would otherwise be wasted in one or more network configurations in which the privacy indicators are implemented.

[0074] It should be recognized that the naming of identifiers referred to herein, e.g., IMSI, etc., is for illustrative purposes only. That is, identifiers for UEs may have different names or acronyms in different protocols and standards for different communication network technologies. As such, any particular names or acronyms given to these identifiers herein are not intended to limit the embodiments in any manner.

[0075] As previously indicated, the embodiments are not limited to LTE or 5G contexts, and the disclosed techniques can be adapted in a straightforward manner to a wide variety of other communication system contexts, including, but not limited to, other 3GPP and non-3GPP systems that employ an identity (e.g., IMSI or equivalent) in the identity request process.

[0076] The processors, memories, controllers, and other components of the user equipment or base station elements of the communications systems disclosed herein may include well-known circuitry suitably modified to implement at least a portion of the identification request functionality described above.

[0077] As described above, embodiments may be implemented in the form of an article of manufacture, each comprising one or more software programs executed by processing circuitry in user equipment, a base station, or other elements of a communications system. Conventional aspects of such circuitry are well known to those skilled in the art and, therefore, will not be described in detail herein. Also, embodiments may be implemented in one or more ASICs, FPGAs, or other types of integrated circuit devices, in any combination. Such integrated circuit devices, and portions or combinations of integrated circuit devices, are examples of "circuitry," as that term is used herein. A wide variety of other arrangements of hardware and associated software or firmware may be used to implement exemplary embodiments.

[0078] Accordingly, it must be re-emphasized that the various embodiments described herein are presented as illustrative examples only and should not be construed as limiting the scope of the claims. For example, alternative embodiments may utilize different communication system configurations, user equipment configurations, base station configurations, identification request processes, messaging protocols, and message formats than those described above in the context of the illustrative embodiments. These and many other alternative embodiments that fall within the scope of the appended claims will be readily apparent to those skilled in the art.

Claims

1. 1. A method comprising: determining, at an element or function in a wireless communication network, one or more first privacy features supported by said wireless communication network; sending, from said element or function, to a user equipment of said wireless communication network, a message including an indication of said one or more first privacy features supported by said wireless communication network; The element or function may include receiving, from the user equipment, a registration request comprising a subscription identifier of a subscriber of the wireless communication network associated with the user equipment, the registration request further comprising one or more second privacy indicators; determining one or more second privacy features of the user equipment for processing the registration request based on the one or more second privacy indicators in the registration request; Including, the message comprises a system information message comprising a master information block or a system information block, the system information message further comprising one or more first privacy indicators selected based on the determined one or more first privacy features, the one or more first privacy indicators comprising an indication of whether the wireless communication network is configured to handle the subscription identifier in the registration request as privacy protected; the one or more first privacy features supported by the wireless communication network comprise an element or functional capability for handling privacy-protected subscription identifiers; the one or more second privacy indicators comprise a field indicating whether the subscription identifier in the registration request is privacy protected. method.

2. The method of claim 1 , wherein the privacy-preserving subscription identifier comprises at least a portion of the subscriber's durable subscription identifier.

3. 2. The method of claim 1 , wherein determining the one or more second privacy features for processing the registration request based on the one or more second privacy indicators comprises removing privacy protection from the subscription identifier in the registration request in response to the field indicating that the subscription identifier is privacy protected.

4. 4. The method of claim 1, wherein an element or function in the wireless communication network comprises a Server Location Function (SLF) that utilizes the subscription identifier to map the registration request to a Home Subscriber Server (HSS) or a User Data Management (UDM) function.

5. 5. The method of claim 1, wherein the privacy-protected subscription identifier is encrypted using a public key of the subscriber's home network operator in the wireless communication network.

6. 6. The method of claim 1, wherein the wireless communication network comprises a 5G system.

7. 2. The method of claim 1, wherein the registration request comprises a request for the user equipment to register with a first type of 4G core network via a second type of 5G radio access network.

8. The method of claim 1 , wherein the registration request is sent from the user equipment to the element or function in response to receiving the message at the user equipment from the element or function.

9. identifying a User Data Management (UDM) function servicing the registration request; providing the registration request to the identified UDM function; The method of claim 1 further comprising:

10. The method of claim 1 , wherein the one or more first privacy indicators comprise an implicit privacy indicator based at least in part on an encryption algorithm scheme used to encrypt the message.

11. 11. An apparatus comprising a processor operatively coupled to a memory and configured to perform the steps of the method of any one of claims 1 to 10.

12. A computer software product comprising executable software code stored on a computer readable medium which, when executed by a computing device, performs the steps of the method of any one of claims 1 to 10.

13. 1. A method comprising: receiving, at a user equipment, from an element or function of a wireless communication network, a message comprising one or more first privacy indicators indicating one or more first privacy features supported by said wireless communication network; generating a registration request comprising a subscription identifier of a subscriber of the wireless communication network associated with the user equipment; determining, at the user equipment, one or more second privacy features for processing the registration request; and adding one or more second privacy indicators to the registration request based on the determined one or more second privacy features for processing the registration request; sending the registration request from the user equipment to the element or function in the wireless communication network, the registration request comprising the one or more second privacy indicators based on the one or more first privacy indicators in the received message; Including, the message received from the element or function of the wireless communication network comprises a system information message comprising a master information block or a system information block, the system information message further comprising the one or more first privacy indicators indicating the one or more first privacy features; the one or more first privacy indicators comprise an indication of whether the wireless communication network is configured to handle the subscription identifier in the registration request with privacy protection; the one or more second privacy indicators comprise a field indicating whether the subscription identifier in the registration request is privacy protected. method.

14. The method of claim 13 , wherein the privacy-preserving subscription identifier comprises at least a portion of the subscriber's durable subscription identifier.

15. 15. The method of claim 13, wherein the element or function in the wireless communication network comprises a Server Location Function (SLF) that utilizes the subscription identifier to map the registration request to a Home Subscriber Server (HSS) or a User Data Management (UDM) function.

16. 16. The method of any one of claims 13 to 15, wherein the privacy-protected subscription identifier is encrypted using a public key of the subscriber's home network operator in the wireless communication network.

17. 17. The method of any one of claims 13 to 16, wherein the wireless communication network comprises a 5G system.

18. 14. The method of claim 13, wherein the registration request comprises a request for the user equipment to register with a 4G core network of a first type via a 5G radio access network of a second type.

19. 19. The method of claim 13, wherein the one or more first privacy indicators comprise an implicit privacy indicator that is based at least in part on an encryption algorithm scheme used to encrypt the message.

20. 20. An apparatus comprising a processor operatively coupled to a memory and configured to perform the steps of the method of any one of claims 13 to 19.

21. A computer-readable recording medium storing executable software code which, when executed by a computing device, performs the steps of the method according to any one of claims 13 to 19.

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