Security management at medium access layer using random data block sizes

Abstract

Techniques are disclosed for security management techniques in a communication network environment. For example, a method includes generating a random number based on a cryptographic value, computing based on the random number, a data block size, and transmitting data, associated with an access control layer (e.g., MAC layer) of a communication network and consistent with the data block size, between user equipment and an access node associated with the communication network.

Description

[0001] SECURITY MANAGEMENT AT MEDIUM ACCESS LAYER USING RANDOM DATA BLOCK SIZES

[0002] Field

[0003] The field relates generally to communication networks, and more particularly, but not exclusively, to security management in such communication networks.

[0004] Background

[0005] This section introduces aspects that may be helpful in facilitating a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

[0006] 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 particularly for human interaction. Next generation or fifth generation (5G) technology is intended to be used not only for human interaction, but also for machine type communications in so-called Internet of Things (loT) networks.

[0007] While 5G networks are intended to enable massive loT services (e.g., very large numbers of limited capacity devices) and mission-critical loT services (e.g., requiring high reliability), improvements over legacy mobile communication services are supported in the form of enhanced mobile broadband (eMBB) services providing improved wireless Internet access for mobile devices.

[0008] In an example communication system, user equipment (5G UE in a 5G network or, more broadly, a UE) such as a mobile terminal (subscriber) communicates over an air interface with a base station or access point of an access network referred to as a 5G AN in a 5G network. The access point (e.g., gNB) is illustratively part of an access network of the communication system.

[0009] For example, in a 5G network, the access network referred to as a 5G AN is described in 5G Technical Specification (TS) 23.501, entitled “Technical Specification Group Services and System Aspects; System Architecture for the 5G System,” and TS 23.502, entitled “Technical Specification Group Services and System Aspects; Procedures for the 5G System (5GS),” the disclosures of which are incorporated by reference herein in their entireties. In general, the access point (e.g., gNB) provides access for the UE to a core network (CN or 5GC), which then provides access for the UE to other UEs and / or a data network such as a packet data network (e.g., Internet).

[0010] TS 23.501 goes on to define a 5G Service-Based Architecture (SBA) which models services as network functions (NFs) that communicate with each other using representational state transfer application programming interfaces (Restful APIs).

[0011] Furthermore, TS 33.501, entitled “Technical Specification Group Services and System Aspects; Security Architecture and Procedures for the 5G System,” the disclosure of which is incorporated by reference herein in its entirety, further describes security management details associated with a 5G network.

[0012] Security management is an important consideration in any communication network environment. However, due to continuing attempts to improve the architectures and protocols associated with a 5G network, and / or other networks, in order to increase network efficiency and / or subscriber convenience, security management issues associated with one or more access control protocol layers of the communication network environment can present a significant technical challenge.

[0013] Summary

[0014] Illustrative embodiments provide security management techniques associated with one or more access control protocol layers of the communication network environment. While illustrative embodiments are described herein in the context of a medium access control (MAC) layer, it is to be appreciated that one or more security management techniques described herein can be applied in other access control protocol layers in a communication network environment.

[0015] By way of example, in one or more other illustrative embodiments, a method includes generating, at user equipment associated with a communication network, a first random number based on a first cryptographic value. The method includes computing, at the user equipment and based on the first random number, a first data block size. The method includes transmitting first data, associated with an access control layer of a communication network and consistent with the first data block size, from the user equipment to an access node associated with the communication network.

[0016] By way of further example, in one or more illustrative embodiments, a method includes generating, at an access node associated with a communication network, a first random number based on a first cryptographic value. The method includes computing, at the access node and based on the first random number, a first data block size. The method includes transmitting first data, associated with an access control layer of a communication network and consistent with the first data block size, from the access node to user equipment associated with the communication network.

[0017] Advantageously, illustrative embodiments provide for encrypting data with random interleaving block sizes in a MAC layer for securing communications at the MAC layer.

[0018] Further illustrative embodiments are provided in the form of a non-transitory computer readable medium having embodied therein executable program code that when executed by a processor causes the processor to perform the above and / or other steps, operations, and the like. Still further illustrative embodiments comprise an apparatus with a processor and a memory configured to perform the above and / or other steps, operations, and the like. Some illustrative embodiments comprise a system configured to perform the above and / or other steps, operations, and the like. Further, some illustrative embodiments comprise an apparatus or a system comprising means for performing the above and / or other steps, operations, and the like.

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

[0020] Brief Description of the Drawings

[0021] FIG. 1 illustrates a communication network environment with which one or more illustrative embodiments may be implemented.

[0022] FIG. 2 illustrates user equipment and entities with which one or more illustrative embodiments may be implemented.

[0023] FIG. 3 illustrates a key derivation chain in a communication network environment.

[0024] FIG. 4 illustrates packet / service data unit correspondence between network protocol layers in a communication network environment.

[0025] FIG. 5 illustrates an example of encrypting data using random interleaving block sizes in a medium access control layer in a communication network environment according to an illustrative embodiment.

[0026] FIG. 6 illustrates respective interleaving functions in user equipment and an access node according to an illustrative embodiment.

[0027] FIG. 7 illustrates respective medium access control packet data unit structures for LTE and 5G NR communication network environments according to an illustrative embodiment. FIG. 8 illustrates respective medium access control packet data unit structures for downlink and uplink in a communication network environment according to an illustrative embodiment.

[0028] FIG. 9 illustrates main fields in a 5GNR medium access control sub-header according to an illustrative embodiment.

[0029] FIG. 10 illustrates examples of block sizes and durations generated using random number generators in an interleaving function according to an illustrative embodiment.

[0030] FIG. 11 illustrates a process flow for encrypting data using random interleaving block sizes in a medium access control layer in a communication network environment according to an illustrative embodiment.

[0031] Detailed Description

[0032] Embodiments will be illustrated herein in conjunction with example communication systems and associated techniques for security management in communication systems. It should be understood, however, that the scope of the claims is not limited to particular types of communication systems and / or processes disclosed. Embodiments can be implemented in a wide variety of other types of communication systems, using alternative processes and operations. For example, although illustrated in the context of wireless cellular systems utilizing the 3rd Generation Partnership Project (3GPP) system elements such as a 3GPP next generation system (5G), the disclosed embodiments can be adapted in a straightforward manner to a variety of other types of communication systems such as 6G communication systems.

[0033] In accordance with illustrative embodiments implemented in a 5G communication system environment, one or more 3 GPP technical specifications (TS) and technical reports (TR) may provide further explanation of network elements / functions and / or operations that may interact with parts of the inventive solutions, e.g., the above-referenced 3GPP TS 23.501, TS 23.502, and TS 33.501. Other 3GPP TS / TR documents may provide other details that one of ordinary skill in the art will realize, for example, TS 38.300 entitled “Technical Specification Group Radio Access Network; NR; NR and NG-RAN Overall Description; Stage 2,” and TS 38.212 entitled “Technical Specification Group Radio Access Network; NR; Multiplexing and Channel Coding,” the disclosures of which are incorporated by reference herein in their entireties. Note that 3GPP TS / TR documents are non-limiting examples of communication network standards (e.g., specifications, procedures, reports, requirements, recommendations, and the like). However, while well-suited for 5G-related 3GPP standards, embodiments are not necessarily intended to be limited to any particular standards.

[0034] It is to be understood that the term 5G network, and the like (e.g., 5G system, 5G communication system, 5G environment, 5G communication environment etc.), in some illustrative embodiments, may be understood to comprise all or part of an access network and all or part of a core network. However, the term 5G network, and the like, may also occasionally be used interchangeably herein with the term 5GC network, and the like, without any loss of generality, since one of ordinary skill in the art understands any distinctions.

[0035] Prior to describing illustrative embodiments, a general description of certain main components of a 5G network will be described below in the context of FIGS. 1 and 2.

[0036] FIG. 1 shows a communication system 100 within which illustrative embodiments are implemented. It is to be understood that the elements shown in communication system 100 are intended to represent some main functions provided within the system, e.g., control plane functions, user plane functions, etc. As such, the blocks shown in FIG. 1 reference specific elements in 5G networks that provide some of these main functions. However, other network elements may be used to implement some or all of the main functions represented. Also, it is to be understood that not all functions of a 5G network are depicted in FIG. 1. Rather, at least some functions that facilitate an explanation of illustrative embodiments are represented. Subsequent figures may depict some additional elements / functions (i.e., network entities).

[0037] Accordingly, as shown, communication system 100 comprises user equipment (UE) 102 that communicates via an air interface 103 with an access point 104. It is to be understood that UE 102 may use one or more other types of access points (e.g., access functions, networks, etc.) to communicate with the 5GC network other than a gNB. By way of example only, the access point 104 may be any 5G access network (gNB), an untrusted non-3GPP access network that uses an Non-3GPP Interworking Function (N3IWF), a trusted non-3GPP network that uses a Trusted Non-3GPP Gateway Function (TNGF) or wireline access that uses a Wireline Access Gateway Function (W-AGF) or may correspond to a legacy access point (e.g., eNB). Furthermore, access point 104 may be a wireless local area network (WLAN) access point as will be further explained in illustrative embodiments described herein.

[0038] The UE 102 may be a mobile station, and such a mobile station may comprise, by way of example, a mobile telephone, a computer, an loT device, or any other type of communication device. The term “user equipment” as used herein is therefore intended to be construed broadly, so as to encompass a variety of different types of mobile stations, subscriber stations or, more generally, communication devices, including examples such as a combination of a data card inserted in a laptop or other equipment such as a smart phone. Such communication devices are also intended to encompass devices commonly referred to as access terminals.

[0039] In one illustrative embodiment, UE 102 is comprised of a Universal Integrated Circuit Card (UICC) part and a Mobile Equipment (ME) part. 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 a permanent subscription identifier and its related key, which are used to uniquely identify and authenticate subscribers to access networks. The ME is the user-independent part of the UE and contains terminal equipment (TE) functions and various mobile termination (MT) functions. Alternative illustrative embodiments may not use UICC-based authentication, e.g., a Non-Public (Private) Network (NPN).

[0040] Note that, in one example, the permanent subscription identifier is an International Mobile Subscriber Identity (IMSI) unique to the UE. In one embodiment, the IMSI is a fixed 15-digit length and consists of a 3-digit Mobile Country Code (MCC), a 3-digit Mobile Network Code (MNC), and a 9-digit Mobile Station Identification Number (MSIN). In a 5G communication system, an IMSI is referred to as a Subscription Permanent Identifier (SUPI). In the case of an IMSI as a SUPI, the MSIN provides the subscriber identity. Thus, only the MSIN portion of the IMSI typically needs to be encrypted. The MNC and MCC portions of the IMSI provide routing information, used by the serving network to route to the correct home network. When the MSIN of a SUPI is encrypted, it is referred to as Subscription Concealed Identifier (SUCI). Another example of a SUPI uses a Network Access Identifier (NAI). NAI is typically used for loT communication.

[0041] The access point 104 is illustratively part of a radio access network or RAN of the communication system 100. Such a radio access network may comprise, for example, a 5G System having a plurality of base stations. Components of a radio access network may, more generally, be considered “radio access entities.”

[0042] Further, the access point 104 in this illustrative embodiment is operatively coupled to an Access and Mobility Management Function (AMF) 106. In a 5G network, the AMF 106 supports, inter alia, mobility management (MM) and security anchor (SEAF) functions.

[0043] AMF 106 in this illustrative embodiment is operatively coupled to (e.g., uses the services of) other network functions 108. Other network functions 108 may include network functions that can act as service producers (NFp) and / or service consumers (NFc). Note that any network function can be a service producer for one service and a service consumer for another service. Further, when the service being provided includes data, the data-providing NFp is referred to as a data producer, while the data-requesting NFc is referred to as a data consumer. A data producer may also be an NF that generates data by modifying or otherwise processing data produced by another NF. Note that NFs may, more generally, be considered “network entities” whereby a network entity that consumes one or more of data and a service can be considered a “consumer network entity” and a network entity that produces one or more of data and a service can be considered a “producer network entity.”

[0044] Note that a UE, such as UE 102, is typically subscribed to what is referred to as a Home Public Land Mobile Network (HPLMN) in which some or all of the functions 106 and 108 reside. Alternatively the UE, such as UE 102, may receive services from an NPN where these functions may reside. The HPLMN is also referred to as the Home Environment (HE). If the UE is roaming (not in the HPLMN), it is typically connected with a Visited Public Land Mobile Network (VPLMN) also referred to as a visited network, while the network that is currently serving the UE is also referred to as a serving network. In the roaming case, some of the functions 106 and 108 can reside in the VPLMN, in which case, functions in the VPLMN communicate with functions in the HPLMN as needed. However, in a non-roaming scenario, access and mobility management functions 106 and the other network functions 108 reside in the same communication network, i.e., HPLMN. Embodiments described herein, unless otherwise specified, are not necessarily limited by which functions reside in which PLMN (i.e., HPLMN or VPLMN).

[0045] The access point 104 is also operatively coupled (via one or more of functions 106 and / or 108) to a Session Management Function (SMF) 110, which is operatively coupled to a User Plane Function (UPF) 112. UPF 112 is operatively coupled to a Packet Data Network, e.g., Internet 114. Note that the thicker solid lines in this figure denote a user plane (UP) of the communication network, as compared to the thinner solid lines that denote a control plane (CP) of the communication network. It is to be appreciated that Internet 114 in FIG. 1 may additionally or alternatively represent other network infrastructures including, but not limited to, cloud computing infrastructure and / or edge computing infrastructure. Further typical operations and functions of such network elements are not described here since they are not the focus of the illustrative embodiments and may be found in appropriate 3GPP 5G documentation. Note that functions shown in 106, 108, 110 and 112 are examples of network functions (NFs). It is to be appreciated that this particular arrangement of system elements is an example only, and other types and arrangements of additional or alternative elements can be used to implement a communication system in other embodiments. For example, in other embodiments, the communication system 100 may comprise other elements / functions not expressly shown herein.

[0046] Accordingly, the FIG. 1 arrangement is just one example configuration of a wireless cellular system, and numerous alternative configurations of system elements may be used. For example, although only single elements / functions are shown in the FIG. 1 embodiment, this is for simplicity and clarity of description only. A given alternative embodiment may of course include larger numbers of such system elements, as well as additional or alternative elements of a type commonly associated with conventional system implementations.

[0047] It is also to be noted that while FIG. 1 illustrates system elements as singular functional blocks, the various subnetworks that make up the 5G network are partitioned into so-called network slices. Network slices (network partitions) are logical networks that provide specific network capabilities and network characteristics that can support a corresponding service type, optionally using network function virtualization (NFV) on a common physical infrastructure. With NFV, network slices are instantiated as needed for a given service, e.g., eMBB service, massive loT service, and mission-critical loT service. A network slice or function is thus instantiated when an instance of that network slice or 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. UE 102 is configured to access one or more of these services via access point 104.

[0048] FIG. 2 is a block diagram illustrating computing architectures for various participants in methodologies according to illustrative embodiments. More particularly, system 200 is shown comprising user equipment (UE) 202 and a plurality of entities 204-1, . . . . , 204-N. For example, in illustrative embodiments and with reference back to FIG. 1, UE 202 can represent UE 102, while entities 204-1, . . . , 204-N can represent functions 106 and 108 (i.e., network entities such as, but not limited to, AMF), as well as access point 104 (i.e., radio access entity such as, but not limited to, a RAN node or gNB). It is to be appreciated that the UE 202 and entities 204-1, . . . . , 204-N are configured to interact to provide security management and other techniques described herein.

[0049] The user equipment 202 comprises a processor 212 coupled to a memory 216 and interface circuitry 210. The processor 212 of the user equipment 202 includes a security management processing module 214 that may be implemented at least in part in the form of software executed by the processor. The security management processing module 214 performs security management described in conjunction with subsequent figures and otherwise herein. The memory 216 of the user equipment 202 includes a security management storage module 218 that stores data generated or otherwise used during security management operations.

[0050] Each of the entities (individually or collectively referred to herein as 204) comprises a processor 222 (222-1, . . . , 222 -N) coupled to a memory 226 (226-1, . . . , 226-N) and interface circuitry 220 (220-1, . . . , 220-N). Each processor 222 of each entity 204 includes a security management processing module 224 (224-1, . . . , 224-N) that may be implemented at least in part in the form of software executed by the processor 222. The security management processing module 224 performs security management operations described in conjunction with subsequent figures and otherwise herein. Each memory 226 of each entity 204 includes a security management storage module 228 (228-1, . . . , 228-N) that stores data generated or otherwise used during security management operations.

[0051] The processors 212 and 222 may comprise, for example, microprocessors such as central processing units (CPUs), application-specific integrated circuits (ASICs), digital signal processors (DSPs) or other types of processing devices, as well as portions or combinations of such elements.

[0052] The memories 216 and 226 may be used to store one or more software programs that are executed by the respective processors 212 and 222 to implement at least a portion of the functionality described herein. For example, security management operations and other functionality as described in conjunction with subsequent figures and otherwise herein may be implemented in a straightforward manner using software code executed by processors 212 and 222.

[0053] A given one of the memories 216 and 226 may therefore be viewed as an example of what is more generally referred to herein as a computer program product or still more generally as a computer or processor readable (non-transitory or storage) medium that has executable program code embodied therein. Other examples of computer or processor readable media may include disks or other types of magnetic or optical media, in any combination. Illustrative embodiments can include articles of manufacture comprising such computer program products or other computer or processor readable media. Further, the memories 216 and 226 may more particularly comprise, for example, electronic random-access memory (RAM) such as static RAM (SRAM), dynamic RAM (DRAM) or other types of volatile or non-volatile electronic memory. The latter may include, for example, non-volatile memories such as flash memory, magnetic RAM (MRAM), phasechange RAM (PC-RAM) or ferroelectric RAM (FRAM). The term “memory” as used herein is intended to be broadly construed, and may additionally or alternatively encompass, for example, a read-only memory (ROM), a disk-based memory, or other type of storage device, as well as portions or combinations of such devices.

[0054] The interface circuitries 210 and 220 illustratively comprise transceivers or other communication hardware or firmware that allows the associated system elements to communicate with one another in the manner described herein.

[0055] It is apparent from FIG. 2 that user equipment 202 and plurality of entities 204 are configured for communication with each other as security management participants via their respective interface circuitries 210 and 220. This communication involves each participant sending data to and / or receiving data from one or more of the other participants. The term “data” as used herein is intended to be construed broadly, so as to encompass any type of information that may be sent between participants including, but not limited to, identity data, key pairs, key indicators, tokens, secrets, security management messages, registration request / response messages and data, request / response messages, authorization and / or authentication request / response messages and data, metadata, control data, audio, video, multimedia, consent data, other messages, etc.

[0056] It is to be appreciated that the particular arrangement of components shown in FIG. 2 is an example only, and numerous alternative configurations may be used in other embodiments. For example, any given network element / function and / or access point can be configured to incorporate additional or alternative components and to support other communication protocols.

[0057] Other system elements such as access point 104, SMF 110, and UPF 112 may each be configured to include components such as a processor, memory and network interface. Also, entities such as third-party applications and network operators can participate in methodologies described herein via computing devices configured to include components such as a processor, memory and network interface. These elements and devices need not be implemented on separate stand-alone processing platforms, but could instead, for example, represent different functional portions of a single common processing platform. More generally, FIG. 2 can be considered to represent processing devices configured to provide respective security management functionalities and operatively coupled to one another in a communication system. By way of example only, all or parts of each of UE 202 and the plurality of entities 204 (e.g., processor and memory) can be considered examples of means for performing one or more operations, one or more steps, one or more functions, one or more processes, etc. as described herein.

[0058] Given the above-described illustrative communication network environments, some realizations regarding communication network architectures that may be implemented therein, such as a 5G New Radio (NR) architecture, are now described.

[0059] A radio access network (RAN) protocol structure of 5G NR includes a medium (or sometimes referred to as media) access control (MAC) layer which logically resides on top of a physical layer. The MAC layer has various functionalities one of which is sending and receiving data and control information in the form of MAC control elements (MAC-CEs). 5G NR defines a list of MAC-CEs since these facilitate faster signaling and consequently reduce latency in terms of switching of beams, bandwidth part (BWP) activation, secondary cell (SCell) activation / deactivation, etc. The MAC-CEs are currently unprotected and hence susceptible to security attacks such as snooping, e.g., reading the unprotected MAC-CE and learning the activated SCell identity and mobility pattern, injecting fake MAC-CE using fake base stations, etc.

[0060] The higher layer data of the RAN protocol stack, such as radio resource control (RRC) and packet data convergence protocol (PDCP) data, are secured using integrity protection and encryption algorithms.

[0061] 5G NR in RAN has keys such as the KRRCint, KRRCenc, Kupint and Kupenc which are derived from KgNB. The primary authentication enables mutual authentication between the UE and the network and provides an anchor key called KSEAF. From KSEAF, KAMF is created during, e.g., primary authentication or non-access stratum (NAS) key re-keying and key refresh events. Based on KAMF, KNASint and KNASenc are then derived when executing a successful NAS security mode command (SMC) procedure. Whenever an initial access stratum (AS) security context needs to be established between UE and gNB, AMF and UE derive a K§NB and a next hop parameter (NH). The KgNB and the NH are derived from the KAMF. For example, FIG. 3 illustrates a key derivation chain 300 consistent with the above-referenced TS 38.300.

[0062] Channel interleaving is a technique used at a physical layer to reduce bit error rate and improve transmission efficiency over fading channels. A channel interleaver disperses the transmission bit stream to minimize the effect of burst errors. An interleaver is used at the transmitting side and de-interleaver is used at the receiving side. There are various methods of interleaving (e.g., see the above-referenced TS 38.212) including, but not limited to: (i) a subblock interleaver wherein a row-wise bit sequence is input and column-wise bits are output; and (ii) a bit interleaver wherein a bit sequence is interleaved to create a specified bit sequence.

[0063] After performing an interleaving process of transport blocks (TB), the MAC layer multiplexes data from multiple UEs to be transmitted in every transmission time interval (TTI). The process of transmitting the multiplexed TBs from gNB and the decoding process at UE is briefly explained below.

[0064] In a 5G network, UE identifies and decodes its TB from the downlink (DL) data sent by gNB based on the following mechanisms and procedures:

[0065] (i) Physical Downlink Control Channel (PDCCH): The PDCCH is used by the gNB to transmit the DL control Information (DCI). The UE monitors the PDCCH for probable DCI transmissions using a blind decoding process. The DCI contains scheduling information that includes the resource allocation and the modulation and coding scheme (MCS) to be used for the DL data transmission over PDSCH.

[0066] DCI also includes a transport block size (TBS) parameter which provides the size of the TB being transmitted and hybrid automatic repeat request (HARQ) process identifier related information for error correction and retransmission to improve decoding success.

[0067] This information is important for the UE to decode the transport block correctly. The DCI is masked with a radio network temporary identifier (RNTI) which is unique to every UE. It is this identifier which enables a UE to identify during the blind decoding process if the DCI is intended for it.

[0068] (ii) C-RNTI (Cell Radio Network Temporary Identifier):

[0069] There are various temporary identifiers used in 5G to identify a UE each serving a particular purpose. The C-RNTI is used to uniquely identify a UE within a cell when in RRC CONNECTED status and is used largely during scheduling. It is important for identifying the UE in DL and UL communications. The UE monitors the PDCCH for DL assignments addressed to its C-RNTI.

[0070] (iii) Physical Downlink Shared Channel (PDSCH):

[0071] The actual DL data is transmitted on the PDSCH. The UE uses the information from the DCI to locate and decode the PDSCH. The PDSCH carries the TB, which the UE decodes using the parameters specified in the DCI. By way of example only, FIG. 4 illustrates packet data unit (PDU) / service data unit (SDU) correspondence between the above-mentioned network protocol layers. An SDU is the data received by a layer from the layer above typically to be modified and then transmitted. For example, the receiving layer converts the SDU into a PDU by adding a header to encapsulate the SDU, e.g., the SDU is a payload of a PDU. A PDU is the basic unit of data that is delivered between entities in a communication network environment using a protocol.

[0072] In 5G RAN, ciphering and integrity protection of control plane (CP) and user plane (UP) data is performed at PDCP. However, the UP control information, especially MAC-CEs, are not currently protected during transmission. This vulnerability may lead to attacks which may hamper UE or network operations, impact UE data reception (e.g., transmission configuration indicator or TCI state), track UE location (e.g., SCell activation, selected beam, timing advance or TA commands) or a denial-of-service (DoS) attack (e.g., by spoofing beam failure discovery or BFR indication from UE), etc.

[0073] Illustrative embodiments overcome the above and other technical challenges associated with unprotected control information, especially MAC-CEs, by providing improved security management techniques.

[0074] For example, some illustrative embodiments use interleaving techniques to encrypt data using random interleaving block sizes in the MAC layer for security. In collocated deployments, the security keys are already generated (as per legacy) for RAN such as Kupenc, KRRCenc can be used as a seed for generation of the random interleaver block sizes. In some implementations, where split gNBs are deployed, new keys can be derived for the purpose of interleaving based encryption at the MAC layer. As these keys are generated at the UE as well as at the gNB independently, there is no signaling exchange of these keys, hence, securing the keys from being detected / accessed by an intruder.

[0075] Advantageously, the interleaving solution is not computationally intensive, thus ensuring that the objective of using lower layer signaling in the RAN in the form of MAC-CEs to reduce latency is still achieved.

[0076] Using a randomness for generating the interleaver sizes ensures that a pattern of the interleaver sizes cannot be established / predicted by an intruder after observing the UE and RAN signaling exchange over a significant period of time. Since each MAC layer can be uniquely managed for a given UE and base station, the random interleaving approach can be used to protect the MAC layer of all the DL and UL channels without any limitation. The type of the security technique used for encrypting MAC packets may be configured in the UE by gNB or by AMF of the serving network using secured signaling at NAS or AS layers. In some illustrative embodiments, the configuration can include the following:

[0077] (i) Block sizes of interleaving to be used. For example, 0, 2, 4, 8, 16 can be the interleaving block sizes. Depending on the block size, the implementations would add padding bits as needed to ensure complete bit interleaving functionality. FIG. 5 illustrates an example 500 of encrypting data using random interleaving block sizes in a MAC layer according to an illustrative embodiment. An input 502 and an output 504 for example 500 is shown. Note that a size of zero would mean no interleaving, and this can be an option if needed for specific scenarios such as testing.

[0078] (ii) Starting block size which is to be used for the first packet being sent at the MAC layer.

[0079] (iii) Periodicity / policy of changing block sizes. For example, if periodicity is 13 MAC packets, after every 13 packets are transmitted over the MAC layer, the block size can be changed. If the policy is random, both UE and base station (BS) can generate random numbers with a seed value taken from one of the RRC layer keys generated. In some illustrative embodiments, a new / different key may also be generated for MAC layer random interleaving. In some embodiments, the probability distribution function to be used by the random number generator can also be part of the policy configuration. Also, which key should be used as seed can be part of a security policy configuration. Using these random numbers, both UE and BS can independently decide on when to change the interleaving block size (e.g., after how many MAC layer transmissions, a new block size should be used). Using padding, the TB size is matched with corresponding interleaving block size.

[0080] As mentioned, example 500 of FIG. 5 shows interleaving with block size 4 including padding bits as required. Note that the padding is required only if the divisibility with block size does not give a remainder of zero. Further, in example 500, the size of input bits is 13 (bit 0 to bit 12). In order to match the block size of 4, 3 padding bits are added at the end as “Pad 1, Pad 2, Pad 3.” Inputs bits including padding bits are arranged in a matrix (502) with a column size of 4, and then columns are read to determine the output bit sequence, i.e., interleaved output bit sequence (504).

[0081] Referring now to FIG. 6, an example 600 of random interleaving functionalities which can be implemented in a UE 602 and a bases station (BS) 604 according to an illustrative embodiment is shown. More particularly, a random interleaving block size determination function in UE 602 can use, for example, Kmacenci as seed for a random number generator, which can generate block sizes for bit interleaving at the MAC layer. Similarly, BS 604 also uses the same key, Kmacenci, as seed for its random number generator. Since both entities are using the same seed and same random number generation function with same probability distribution function (as per policy), both will generate the same block sizes.

[0082] A random interleaving block size change duration determination function in UE 602 can use, for example, Kmacenc2 as seed for random number generator. The number generated by this function determines after how many MAC packets a new block size (which is again generated using the previously defined random number generator) will be used. Similar functionality in BS 604 uses the same key, and hence, is synchronized with UE 602.

[0083] FIG. 7 illustrates an example 700 of respective MAC PDU structures for LTE and 5G NR communication network environments according to an illustrative embodiment, while FIG. 8 illustrates an example 800 of respective MAC PDU structures for DL and UL according to an illustrative embodiment. Implementations of FIG. 6 may differ in terms of the keys used by both the random interleaving functions or usage of one or both random number generators. For example, some illustrative embodiments may just use sequential block sizes such as 0, 2, 4, 8, 16 ... but keep changing the block sizes after a random number of MAC TB transmissions. New MAC encryption keys - Kmacenci and Kmacenc2 - can be derived by UE 602 as well as BS 604 using KgNB along with a unique parameter. This unique parameter can be, for example, the logical channel identifier (LCID) of first / second MAC subPDU. Both keys can be derived with different LCIDs. Which LCID needs to be used by the UE 602 can be decided by BS 604 and provided along with a random MAC interleaving configuration message, which is described below. Note that it is important that these keys are generated independently by UE 602 and BS 604, and not transmitted over the air. In the case of split gNBs, these keys can be generated at the same entity where other RAN keys are generated. This could be in gNB-CU. UE 602 need not know about the split gNB or non-split gNB architecture in this case. The UE can independently generate these keys using the same key derivation function (KDF) as the RAN.

[0084] Policy configurations received from the core network can determine which keys to use, block size of the first MAC TB, etc., as described above. Note that a MAC TB, i.e., a MAC PDU consists of multiple MAC subPDUs and / or MAC CEs. This can be seen from FIG. 8. In transparent MAC (e g., BCH, PCH, BCCH on DL-SCH, SL-BCH), there is no MAC subheader. One MAC SDU is aligned to the TB size. Illustrative embodiments provide for interleaving of all bits of a MAC PDU (TB). In some illustrative embodiments, a more complex scheme of random interleaving for MAC subPDUs may be used.

[0085] Moreover, interleaving using randomness, according to illustrative embodiments, can work as encryption for any man-in-the-middle scenario and ensure that MAC-CE vulnerabilities can be mitigated because even MAC-CE bits will now be interleaved. For shared channels, there is no MAC subheader, and the receiver can first de-interleave the MAC PDU (or MAC subPDU), and then detect the headers / subheaders, LCID and MAC-CE bits. This ensures that the proposed random interleaving approach does not affect any of the legacy methods for shared or dedicated channels.

[0086] As further collectively demonstrated by FIGS. 7 and 8, multiple MAC SDUs and MAC- CEs (sent with its own sub-header) can be part of a single MAC PDU. A MAC PDU is packaged as a TB and sent on a transport channel to PHY layer for transmission. A MAC subPDU typically starts with a subheader. Subheader is followed by a MAC SDU, a MAC CE or padding. When a set of MAC subPDUs does not exactly fill a TB, a MAC subPDU with padding is included. A MAC subPDU with only a subheader implies zero-length padding. Only one MAC PDU is allowed in a TB. MAC SDUs, CEs and subheaders are all byte aligned and in multiples of 8 bits. The leftmost bit is the most significant bit. The order of subPDUs in a MAC PDU is defined. In sidelink and uplink, the order of concatenation is MAC SDUs, CEs and padding. In downlink, the order is MAC-CEs, SDUs and padding. In all cases, padding typically is the last subPDU. MAC SDUs are of variable size, except for an SDU carrying UL CCCH. Some MAC-CEs are of fixed size while others are of variable size.

[0087] FIG. 9 depicts an example 900 according to an illustrative embodiment where LCID (logical channel ID) and eLCID (extended logical channel ID) are shown. LCID values and meanings differ for downlink, uplink and sidelink. In DL-SCH, LCID=0 indicates CCCH. In UL-SCH, LCID values 0 or 52 indicate CCCH. In both DL and UL, values 1-32 indicate identity of the logical channel since the MAC layer does the multiplexing / demultiplexing of RLC PDUs coming via logical channels. Many other values indicate that a MAC subPDU contains MAC-CE. LCID=63 is for padding. Values 33 or 34 imply that the eLCID field is present in the subheader.

[0088] FIG. 10 shows an example 1000 of the numbers generated from the two random generators described above according to an illustrative embodiment. Interleaving is performed for each MAC TB to be transmitted to UE. The gNB (BS) MAC multiplexes TBs of multiple UEs for transmission in the TTI. As described above, the UE decodes the TB intended for it based on the DCI information received over PDCCH.

[0089] Referring now to FIG. 11, a process flow 1100 is shown for encrypting data using random interleaving block sizes in a medium access control layer in a communication network environment according to an illustrative embodiment. The process flow 1100 involves a UE 1100 and a gNB 1104. Steps 1-11 of the process flow 1100 will now be described.

[0090] Step 1 : UE Authentication, NAS and AS security context establishment is completed.

[0091] Step 2: Two options are proposed based on the gNB architecture:

[0092] Option 1 : gNB CU-DU split: In the gNB split architecture, DU is the most deployed NF at less secure environments, and it is not safe to transfer the encryption keys from CU to DU. Hence, in one illustrative embodiment, new keys are generated at gNB DU for seeding the random MAC interleaver. Alternatively, it is realized that F1AP is secure signalling service / interface with Internet Protocol Security (IPSec) and other protection mechanisms such as Transport Layer Security (TLS). Important information can be sent securely over the F1AP interface from CU to DU in 5G. Hence, in another illustrative embodiment, keys are generated at CU and passed to DU over a secure interface such as F1AP or the like.

[0093] Option 2: gNB CU-DU co-located: If CU and DU are co-located, the encryption keys used for ciphering and integrity protection may be used for seeding the random MAC interleaver.

[0094] Steps 3 and 4: Random MAC interleaving configuration / response is performed between gNB 1104 and UE 1102. This can include the configuration for generating keys for MAC interleaving.

[0095] Step 5: For option 1, i.e., gNB CU-DU split architecture, UE 1102 generates keys for seeding the random MAC interleaver after receiving the configuration from gNB. Similarly, gNB 1104 generates keys for seeding the random MAC interleaver after receiving the acknowledgement from UE 1102.

[0096] Data transfer procedure:

[0097] Below steps are applicable for each packet scheduled for transmission:

[0098] Step 6: UE 1102 and gNB 1104 each derive the random interleaving block size as per the configuration.

[0099] Step 7: UE 1102 and gNB 114 each apply the block interleaving for the packets scheduled for transmission. The interleaving may be applied for the whole packet or for the specific portion of the packet such as MAC-CEs.

[0100] Steps 8 and 10: Data transfer of interleaved MAC TB occurs in UL and DL.

[0101] Steps 9 and 11 : The receiving entity (i.e., gNB 1104 or UE 1102) will de-interleave the received packet as per the expected interleaving block size.

[0102] Accordingly, one or more illustrative embodiments may include an apparatus including at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: generate a first random number based on a first cryptographic value; compute, based on the first random number, a first data block size; and transmit first data, associated with an access control layer of a communication network, consistent with the first data block size.

[0103] In some illustrative embodiments, the apparatus may further be caused to: generate a second random number based on a second cryptographic value; compute, based on the second random number, a second data block size; and change a data block size to be applied for second data to be transmitted, associated with the access control layer of a communication network, from the first data block size to the second block size; and transmit the second data consistent with the second data block size.

[0104] In some illustrative embodiments, the apparatus may further be caused to interleave input data bits to generate data blocks of the first data based on the first data block size. Similarly, interleaving may be done for input data bits to generate data blocks of the second data based on the second data block size.

[0105] In some illustrative embodiments, the apparatus may further be caused to add one or more padding bits to one or more of the data blocks such that each data block is equal to the first data block size. Similarly, adding one or more padding bits may be done to one or more of the data blocks such that each data block is equal to the second data block size.

[0106] In some illustrative embodiments, changing of the data block size may be based on a randomly computed time duration and / or a data block size time duration policy.

[0107] In some illustrative embodiments, the first cryptographic value may include a first cryptographic key. The first cryptographic key may include a cryptographic key generated for computing a data block size and / or generated for one or more functions in the communication network other than computing a data block size.

[0108] In some illustrative embodiments, the at least one processor and the at least one memory are a part of user equipment accessing the communication network via an access node. In some illustrative embodiments, the apparatus may further be caused to receive security configuration data used to compute the first data block size from the access node.

[0109] In some illustrative embodiments, the apparatus may further be caused to receive security configuration data used to compute the first data block size from a network function associated with the communication network.

[0110] In some illustrative embodiments, the at least one processor and the at least one memory are a part of an access node of the communication network.

[0111] In one or more other illustrative embodiments, a method may include: generating, at user equipment associated with a communication network, a first random number based on a first cryptographic value; computing, at the user equipment and based on the first random number, a first data block size; and transmitting first data, associated with an access control layer of a communication network and consistent with the first data block size, from the user equipment to an access node associated with the communication network.

[0112] In one or more further illustrative embodiments, a method may include: generating, at an access node associated with a communication network, a first random number based on a first cryptographic value; computing, at the access node and based on the first random number, a first data block size; and transmitting first data, associated with an access control layer of a communication network and consistent with the first data block size, from the access node to user equipment associated with the communication network.

[0113] It is to be appreciated that the particular processing operations and other system functionality described in conjunction with the diagrams described herein are presented by way of illustrative example only and should not be construed as limiting the scope of the disclosure in any way. Alternative embodiments can use other types of processing operations and messaging protocols. For example, the ordering of the steps may be varied in other embodiments, or certain steps may be performed at least in part concurrently with one another rather than serially. Also, one or more of the steps may be repeated periodically, or multiple instances of the methods can be performed in parallel with one another.

[0114] It should again be emphasized that the various embodiments described herein are presented by way of illustrative example only and should not be construed as limiting the scope of the claims. For example, alternative embodiments can utilize different communication system configurations, user equipment configurations, base station configurations, authorization processes, messaging protocols and message formats than those described above in the context of the illustrative embodiments. These and numerous other alternative embodiments within the scope of the appended claims will be readily apparent to those skilled in the art.

Claims

CLAIMS1. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: generate a first random number based on a first cryptographic value; compute, based on the first random number, a first data block size; and transmit first data, associated with an access control layer of a communication network, consistent with the first data block size.

2. The apparatus of claim 1, wherein the at least one memory storing instructions, when executed by the at least one processor, further cause the apparatus at least to: generate a second random number based on a second cryptographic value; compute, based on the second random number, a second data block size; change a data block size to be applied for second data to be transmitted, associated with the access control layer of a communication network, from the first data block size to the second block size; and transmit the second data consistent with the second data block size.

3. The apparatus of claim 2, wherein the at least one memory storing instructions, when executed by the at least one processor, further cause the apparatus to at least one of: interleave input data bits to generate data blocks of the first data based on the first data block size; and interleave input data bits to generate data blocks of the second data based on the second data block size.

4. The apparatus of claim 3, wherein the at least one memory storing instructions, when executed by the at least one processor, further cause the apparatus to at least one of: add one or more padding bits to one or more of the data blocks such that each data block is equal to the first data block size; and add one or more padding bits to one or more of the data blocks such that each data block is equal to the second data block size.

5. The apparatus of claim 2, wherein the changing of the data block size is based on a randomly computed time duration.

6. The apparatus of claim 2, wherein the changing of the data block size is based on a data block size time duration policy.

7. The apparatus of claim 1, wherein the first cryptographic value comprises a first cryptographic key.

8. The apparatus of claim 7, wherein the first cryptographic key comprises a cryptographic key generated for computing a data block size.

9. The apparatus of claim 7, wherein the first cryptographic key comprises a cryptographic key generated for one or more functions in the communication network other than computing a data block size.

10. The apparatus of claim 1, wherein the at least one processor and the at least one memory are a part of user equipment accessing the communication network via an access node.

11. The apparatus of claim 10, wherein the at least one memory storing instructions, when executed by the at least one processor, further cause the apparatus at least to: receive security configuration data used to compute the first data block size from the access node.

12. The apparatus of claim 10, wherein the at least one memory storing instructions, when executed by the at least one processor, further cause the apparatus at least to: receive security configuration data used to compute the first data block size from a network function associated with the communication network.

13. The apparatus of claim 1, wherein the at least one processor and the at least one memory are a part of an access node of the communication network.

14. A method comprising: generating, at user equipment associated with a communication network, a first random number based on a first cryptographic value; computing, at the user equipment and based on the first random number, a first data block size; and transmitting first data, associated with an access control layer of a communication network and consistent with the first data block size, from the user equipment to an access node associated with the communication network.

15. The method of claim 14, further comprising: generating, at the user equipment, a second random number based on a second cryptographic value; computing, at the user equipment and based on the second random number, a second data block size; changing, at the user equipment, a data block size to be applied for second data to be transmitted, associated with the access control layer of a communication network, from the first data block size to the second block size; and transmitting the second data consistent with the second data block size from the user equipment to the access node.

16. The method of claim 15, further comprising at least one of: interleaving input data bits, at the user equipment, to generate data blocks of the first data based on the first data block size; and interleaving input data bits, at the user equipment, to generate data blocks of the second data based on the second data block size.

17. The method of claim 16, further comprising at least one of: adding, at the user equipment, one or more padding bits to one or more of the data blocks such that each data block is equal to the first data block size; and adding, at the user equipment, one or more padding bits to one or more of the data blocks such that each data block is equal to the second data block size.

18. The method of claim 15, wherein the changing of the data block size is based on a randomly computed time duration.

19. The method of claim 15, wherein the changing of the data block size is based on a data block size time duration policy.

20. The method of claim 14, wherein the first cryptographic value comprises a first cryptographic key.

21. The method of claim 20, wherein the first cryptographic key comprises a cryptographic key generated for computing a data block size.

22. The method of claim 20, wherein the first cryptographic key comprises a cryptographic key generated for one or more functions in the communication network other than computing a data block size.

23. The method of claim 14, further comprising: receiving security configuration data used to compute the first data block size at the user equipment from the access node.

24. The method of claim 14, further comprising: receiving security configuration data used to compute the first data block size at the user equipment from a network function associated with the communication network.

25. A method comprising: generating, at an access node associated with a communication network, a first random number based on a first cryptographic value; computing, at the access node and based on the first random number, a first data block size; and transmitting first data, associated with an access control layer of a communication network and consistent with the first data block size, from the access node to user equipment associated with the communication network.

26. The method of claim 25, further comprising: generating, at the access node, a second random number based on a second cryptographic value; computing, at the access node and based on the second random number, a second data block size; changing, at the access node, a data block size to be applied for second data to be transmitted, associated with the access control layer of a communication network, from the first data block size to the second block size; and transmitting the second data consistent with the second data block size from the access node to the user equipment.

27. The method of claim 26, further comprising at least one of: interleaving input data bits, at the access node, to generate data blocks of the first data based on the first data block size; and interleaving input data bits, at the access node, to generate data blocks of the second data based on the second data block size.

28. The method of claim 27, further comprising at least one of: adding, at the access node, one or more padding bits to one or more of the data blocks such that each data block is equal to the first data block size; and adding, at the access node, one or more padding bits to one or more of the data blocks such that each data block is equal to the second data block size.

29. The method of claim 26, wherein the changing of the data block size is based on a randomly computed time duration.

30. The method of claim 26, wherein the changing of the data block size is based on a data block size time duration policy.

31. The method of claim 25, wherein the first cryptographic value comprises a first cryptographic key.

32. The method of claim 31, wherein the first cryptographic key comprises a cryptographic key generated for computing a data block size.

33. The method of claim 31, wherein the first cryptographic key comprises a cryptographic key generated for one or more functions in the communication network other than computing a data block size.

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