Patent Description:
Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.).

<CIT> relates to configurable access stratum (AS) security. <CIT> relates to techniques for use in securely communicating a data packet vua at least one relay user equipment. <CIT> relates to a mobile communication method, apparatus, and device. <CIT> relates to a wireless communication device, a wireless communication system, and a wireless communication method.

In the following, each of the described methods, apparatuses, examples, and aspects which does not fully correspond to the invention as defined in the claims is thus not according to the invention and is, as well as the whole following description, present for illustration purposes only or to highlight specific aspects or features of the claims.

In a wireless network, a BS and a UE may communicate using various protocol layers, such as a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, a medium access control (MAC) layer, and/or the like. In some cases, some of the protocol layers, such as the PDCP layer (which may be used for control plane signaling and user plane data), may be security protected using various techniques. However, some layers, such as the MAC layer, may not be security protected. Since the MAC layer may carry performance-critical information, such as buffer status reports, timing advance information, transmission configuration indication (TCI) state information, and/or the like, the lack of MAC layer security may leave the MAC layer vulnerable to attacks (e.g., denial of service (DoS) attacks, man-in-the-middle attacks, and/or other types of attacks). As a result, a malicious entity may be allowed to alter the buffer status report information (which may cause performance degradations in resource scheduling), the timing advance information (which may cause desynchronization between the UE and the BS), the TCI state information (which may cause beam and/or precoding mismatches between the UE and the BS), and/or the like.

Some aspects, described herein, provide techniques and apparatuses for MAC security. In some aspects, a UE may transmit, to a BS, an indication of a MAC security capability. The BS may transmit, to the UE, an indication of a MAC security configuration for communications between the UE and the BS. The MAC security configuration may be based at least in part on the UE's MAC security capability, and may indicate a level of MAC security that is to be used when encrypting, decrypting, and/or integrity protecting MAC protocol data units (PDUs) transmitted between the UE and the BS. Moreover, the UE and the BS may generate various keys that may be used when encrypting, decrypting, and/or integrity protecting MAC PDUs transmitted between the UE and the BS. In this way, the UE and the BS may implement MAC security for MAC PDUs transmitted between the UE and the BS, which increases the security of the MAC PDUs, prevents performance degradations and attacks of the MAC PDUs, and/or the like.

These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements").

A relay station may also be referred to as a relay BS, a relay base station, a relay, etc..

Wireless network <NUM> may be a heterogeneous network that includes BSs of different types, e.g., macro BSs, pico BSs, femto BSs, relay BSs, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in wireless network <NUM>.

A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, a station, etc. A UE may be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium.

MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a base station, another device (e.g., remote device), or some other entity.

Transmit processor <NUM> may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.) and provide overhead symbols and control symbols.

A channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), etc. In some aspects, one or more components of UE <NUM> may be included in a housing.

On the uplink, at UE <NUM>, a transmit processor <NUM> may receive and process data from a data source <NUM> and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, etc.) from controller/processor <NUM>. The symbols from transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to base station <NUM>.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with MAC security, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG>, process <NUM> of <FIG>, and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively.

The stored program codes, when executed by processor <NUM> and/or other processors and modules at UE <NUM>, may cause the UE <NUM> to perform operations described with respect to process <NUM> of <FIG> and/or other processes as described herein. The stored program codes, when executed by processor <NUM> and/or other processors and modules at base station <NUM>, may cause the base station <NUM> to perform operations described with respect to process <NUM> of <FIG> and/or other processes as described herein.

In some aspects, UE <NUM> may include means for transmitting, to a BS <NUM>, information indicating a MAC security capability of the UE <NUM>, means for receiving, from the BS <NUM>, a communication that includes an indication of a MAC security configuration for communications between the UE <NUM> and the BS <NUM>, wherein the indication of the MAC security configuration is based at least in part on the MAC security capability of the UE <NUM>, and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>.

In some aspects, base station <NUM> may include means for receiving, from a UE <NUM>, information indicating a MAC security capability of the UE <NUM>, means for transmitting, to the UE <NUM>, a communication that includes an indication of a MAC security configuration for communications between the UE <NUM> and the BS <NUM>, wherein the indication of the MAC security configuration is based at least in part on the MAC security capability of the UE <NUM>, and/or the like. In some aspects, such means may include one or more components of base station <NUM> described in connection with <FIG>.

For example, the functions described with respect to the transmit processor <NUM>, the receive processor <NUM>, and/or the TX MIMO processor <NUM> may be performed by or under the control of processor <NUM>.

In some aspects, a CU of a BS may generate a BS key for various security implementations associated with the BS. The various security implementations may include encryption/decryption, integrity protection, and/or the like. In some aspects, the CU may generate one or more other keys based at least in part on the BS key, such as one or more keys for radio resource control (RRC) security at the CU and/or a DU associated with the BS, one or more keys for user plane (UP) security at the CU and/or a DU associated with the BS, one or more keys for MAC security at the CU and/or the DU associated with the BS, and/or the like. In some aspects, the CU and/or the DU may use the one or more keys, that are generated based at least in part on the BS key, to encrypt and decrypt communications with a UE, integrity protect communications with a UE, and/or the like.

As indicated above in <FIG>, a BS may include a central unit (CU) (e.g., C-CU <NUM>) and/or one or more distributed units (e.g., one or more DUs <NUM>). In some aspects, a C-CU <NUM> of a BS may generate a BS key for various security implementations associated with the BS. The various security implementations may include encryption/decryption, integrity protection, and/or the like. In some aspects, the C-CU <NUM> may generate one or more other keys based at least in part on the BS key, such as one or more keys for radio resource control (RRC) security at the C-CU <NUM> and/or a DU <NUM> associated with the BS, one or more keys for user plane (UP) security at the C-CU <NUM> and/or a DU <NUM> associated with the BS, one or more keys for MAC security at the C-CU <NUM> and/or the DU <NUM> associated with the BS, and/or the like. In some aspects, the C-CU <NUM> and/or the DU <NUM> may use the one or more keys, that are generated based at least in part on the BS key, to encrypt and decrypt communications with a UE, integrity protect communications with a UE, and/or the like.

<FIG> are diagrams illustrating an example <NUM> of MAC security, in accordance with various aspects of the present disclosure. As shown in <FIG>, example <NUM> may include a BS <NUM> and a UE <NUM>. In some aspects, BS <NUM> and UE <NUM> may be included in a wireless network (e.g., wireless network <NUM>). In some aspects BS <NUM> may include a CU (e.g., a C-CU <NUM> or another type of CU) and one or more DUs (e.g., DU <NUM>).

As shown in <FIG>, and by reference number <NUM>, to initiate MAC security between BS <NUM> and UE <NUM>, UE <NUM> may transmit, to BS <NUM>, information indicating a MAC security capability of UE <NUM>. In some aspects, UE <NUM> may transmit the information indicating the MAC security capability of UE <NUM> based at least in part on communicatively connecting with BS <NUM>, based at least in part on being handed over to BS <NUM>, and/or the like. In some aspects, the information indicating the MAC security capability of the UE may include information identifying whether UE <NUM> is capable of implementing MAC security at a MAC protocol data unit (PDU) level, at a MAC sub-PDU type level, at an individual MAC- control element (MAC-CE) level, and/or the like.

In some aspects, a MAC PDU may include a plurality of MAC sub-PDUs. A subset of the plurality of MAC sub-PDUs may include MAC-CEs while other MAC sub-PDUs, of the plurality of MAC sub-PDUs may include MAC service data units (SDUs) or padding (e.g., bits that are added to the MAC PDU to align the size of the MAC PDU with an expected transport block size (TBS) of the MAC PDU).

In some aspects, a MAC PDU level of MAC security may include the capability of either securing an entire MAC PDU or not securing an entire MAC PDU. In this case, UE <NUM> is capable of either securing all MAC sub-PDUs or no MAC sub-PDUs in a MAC PDU. In some aspects, a MAC sub-PDU type level of MAC security may include the capability of selectively securing certain types of MAC sub-PDUs, included in a MAC PDU, which reduces the overhead of applying MAC security to a MAC PDU. For example, UE <NUM> may be capable of selectively securing only MAC sub-PDUs that include a MAC-CE. In some aspects, a MAC-CE level of MAC security may include the capability of selectively securing particular MAC-CEs, which further reduces the overhead of applying MAC security to a MAC PDU, while increasing the flexibility of applying MAC security to the MAC PDU.

As further shown in <FIG>, and by reference number <NUM>, BS <NUM> may transmit, to UE <NUM>, an indication of a MAC security configuration for communications between UE <NUM> and BS <NUM>. In some aspects, BS <NUM> may transmit the indication of the MAC security configuration based at least in part on receiving the indication of the MAC security capability of UE <NUM>, based at least in part on a handover, of UE <NUM>, being initiated, and/or the like. In some aspects, the handover may include an intra-BS handover, such as a handover between a first DU of BS <NUM> and a second DU of BS <NUM>. In some aspects, the handover may include an inter-BS handover (which may also be referred to as an Xn-base handover), such as a handover between another BS and BS <NUM>, a handover between a DU of another BS to a DU of BS <NUM>, and/or the like. In some aspects, BS <NUM> may transmit the indication of the MAC security configuration in a RRC reconfiguration communication and/or another type of signaling communication.

In some aspects, the indication of the MAC security configuration may indicate a level of MAC security that is to be applied to MAC PDUs transmitted between UE <NUM> and BS <NUM>. For example, the indication of the MAC security configuration may indicate that a MAC PDU level of MAC security is to be applied to MAC PDUs transmitted between UE <NUM> and BS <NUM>, may indicate that a MAC sub-PDU type level of MAC security is to be applied to MAC PDUs transmitted between UE <NUM> and BS <NUM>, or may indicate that a MAC-CE level of MAC security is to be applied to MAC PDUs transmitted between UE <NUM> and BS <NUM>.

In some aspects, the indication of the MAC security configuration may be based at least in part on the MAC security capability of UE <NUM>. For example, BS <NUM> may configure the indication of the MAC security configuration to match the MAC security capability of UE <NUM>. In this way, BS <NUM> may configure the indication of the MAC security configuration such that the MAC security configuration is compatible with the MAC security capability of UE <NUM>. In some aspects, the indication of the MAC security configuration may be based at least in part on other factors, such as available bandwidth on the connection between UE <NUM> and BS <NUM>, based at least in part on the types of information being transmitted in a particular MAC PDU, based at least in part on BS <NUM> to be configured to pick the highest or lowest level of MAC security that UE <NUM> can support, and/or other factors.

As shown in <FIG>, and by reference number <NUM>, UE <NUM> and BS <NUM> may generate one or more keys. In some aspects, BS <NUM> may generate the one or more keys based at least in part on receiving the indication of the MAC security capability of UE <NUM>, based at least in part on a handover, of UE <NUM>, being initiated, and/or the like. In some aspects, UE <NUM> may generate the one or more keys based at least in part on receiving an indication to generate the one or more keys (e.g., in the RRC reconfiguration communication that includes the indication of the MAC security configuration), based at least in part on a handover, of UE <NUM>, being initiated, and/or the like.

<FIG> illustrate various key structures for the one or more keys that may be generated by UE <NUM> and BS <NUM>. As shown in <FIG>, UE <NUM> and BS <NUM> may generate a BS key associated with BS <NUM> (KBS), one or more sets of keys associated with a CU of BS <NUM>, one or more keys associated with a DU of BS <NUM>, and/or the like.

As shown in <FIG>, if RRC communication initiates and terminates at the CU of BS <NUM>, the one or more sets of keys, associated with the CU, may include a set of RRC keys and a set of UP keys. The set of RRC keys may include an RRC encryption key (KRRCEnc) and an RRC integrity key (KRRCInt). KRRCEnc may be used to encrypt and decrypt RRC communications between BS <NUM> and UE <NUM>, and KRRCInt may be used to integrity protect RRC communications between BS <NUM> and UE <NUM>. The set of UP keys may include a UP encryption key (KUPEnc) and a UP integrity key (KUPInt). KUPEnc may be used to encrypt and decrypt UP communications between BS <NUM> and UE <NUM>, and KUPInt may be used to integrity protect UP communications between BS <NUM> and UE <NUM>.

As further shown in <FIG>, if RRC communication initiates and terminates at the CU of BS <NUM>, the one or more sets of keys, associated with the DU, may include a DU key (KDU) and plurality of MAC security keys. UE <NUM> and BS <NUM> may generate the plurality of MAC security keys based at least in part on KDU. The plurality of MAC security keys may include a MAC encryption key (KMACEnc) and a MAC integrity key (KMACInt). UE <NUM> and BS <NUM> may use KMACEnc, depending on the MAC security configuration indicated by BS <NUM>, to encrypt and decrypt entire MAC PDUs, MAC sub-PDUs that include MAC-CEs, or MAC sub-PDUs that include particular MAC-CEs. UE <NUM> and BS <NUM> may use KMACInt, depending on the MAC security configuration indicated by BS <NUM>, to integrity protect entire MAC PDUs, MAC sub-PDUs that include MAC-CEs, or MAC sub-PDUs that include particular MAC-CEs.

In some aspects, UE <NUM> and BS <NUM> may generate KRRCEnc, KRRCInt, KUPEnc, KUPInt, and KDU based at least in part on KBS. For example, UE <NUM> and BS <NUM> may generate KRRCEnc, KRRCInt, KUPEnc, and KUPInt from KBS using a key derivation function as described in 3GPP TS <NUM>. As another example, UE <NUM> and BS <NUM> may generate KDU from KBS using a key derivation function according to Equation <NUM>: <MAT>
where PDU includes one or more parameters unique to the DU of BS <NUM>, and DH includes one or more Diffie-Hellman parameters for Diffie-Hellman key generation between UE <NUM> and BS <NUM>. In some aspects, UE <NUM> and BS <NUM> may generate KMACEnc and KMACInt from KDU in a manner similar to which KRRCEnc, KRRCInt, KUPEnc, and KUPInt are generated from KBS.

In some aspects, the one or more parameters unique to the DU of BS <NUM> may include a physical cell identifier (PCI) associated with the DU, a random number that is randomly generated by the DU, an alphanumeric string that is unique to the DU, another type of identifier that is unique to the DU, and/or any other parameters that distinguish the DU from other DUs of BS <NUM> and/or other DUs of other BSs included in the wireless network. In some aspects, BS <NUM> may transmit the one or more parameters, unique to the DU of BS <NUM>, in the same communication that includes the indication of the MAC security configuration or in a different communication.

As shown in <FIG>, if RRC communication initiates and terminates at the DU of BS <NUM>, the one or more sets of keys, associated with the CU, may include the set of UP keys (KUPEnc and KUPInt). The one or more sets of keys, associated with the DU, may include the DU key (KDU), the set of RRC keys (KRRCEnc and KRRCInt), and the set of MAC security keys (KMACEnc and KMACInt). In this case, UE <NUM> and BS <NUM> may generate KUPEnc and KUPInt from KBS, may generate KDU based at least in part on Equation <NUM> above, and may generate KRRCEnc, KRRCInt, KMACEnc, and KMACInt from KDU.

As shown in <FIG>, if RRC communication initiates and terminates at the DU of BS <NUM>, instead of having separate sets of keys for RRC communication and MAC security, UE <NUM> and BS <NUM> may generate one set of keys, from KDU, for DU encryption (KDUEnc) and DU integrity protection (KDUInt). In this case, UE <NUM> and BS <NUM> may generate KUPEnc and KUPInt from KBS, may generate KDU based at least in part on Equation <NUM> above, and may generate KDUEnc and KDUInt from KDU. UE <NUM> and BS <NUM> may use KDUEnc for both RRC encryption and decryption and MAC encryption and decryption. Similarly, UE <NUM> and BS <NUM> may use KDUInt for both RRC integrity protection and MAC integrity protection.

As shown in <FIG>, and by reference number <NUM>, UE <NUM> and BS <NUM> may implement MAC security for a MAC PDU communication transmitted between UE <NUM> and BS <NUM>. In some aspects, UE <NUM> and BS <NUM> may implement the MAC security based at least in part on the MAC security configuration indicated by BS <NUM>, based at least in part on the one or more keys generated by UE <NUM> and BS <NUM>, and/or the like.

In some aspects, UE <NUM> and/or a DU of BS <NUM> may generate a MAC PDU communication, that is to transmitted, such that the MAC PDU communication includes a plurality of MAC sub-PDUs. The plurality of MAC sub-PDUs may include a MAC security CE, one or more MAC-CEs, one or more MAC SDUs, and/or padding. In some aspects, UE <NUM> and/or the DU of BS <NUM> may configure the MAC security CE to include information associated with MAC security for the MAC PDU communication. The information associated with MAC security for the MAC PDU communication may be based at least in part on the MAC security configuration for communications between UE <NUM> and BS <NUM>.

For example, if the MAC security configuration indicates that MAC security is to be used for the entire MAC PDU communication, the information associated with MAC security for the MAC PDU communication may include an indication of a length of the MAC PDU communication. UE <NUM> and/or the DU of BS <NUM> may use the indication of the length of the MAC PDU communication to determine a quantity of bits, included in the MAC PDU communication, that are to be decoded and/or integrity checked.

As another example, if the MAC security configuration indicates that MAC security is to be used for all MAC sub-PDUs that include a MAC-CE, the information associated with MAC security for the MAC PDU communication may include an indication of a quantity of all MAC sub-PDUs, included in the MAC PDU communication, that include a MAC-CE, and an indication of a combined length of all MAC sub-PDUs, included in the MAC PDU communication, that include a MAC-CE. Since the MAC sub-PDUs that include MAC-CEs may be located in a continuous block in the MAC PDU communication, UE <NUM> and/or the DU of BS <NUM> may use the indication of the combined length to identify the contiguous block of MAC sub-PDUs, and may use the indication of the quantity to determine a quantity of MAC sub-PDUs, included in the continuous block, that are to be decrypted and/or integrity checked.

As another example, if the MAC security configuration indicates that MAC security is to be used for a subset of MAC sub-PDUs that include a MAC-CE, the information associated with MAC security for the MAC PDU communication may include an indication of a quantity of MAC sub-PDUs, included in the subset of MAC sub-PDUs, may include an indication of respective identifiers associated with the subset of MAC sub-PDUs, and may include an indication of respective lengths of the subset of the MAC sub-PDUs. UE <NUM> and/or the DU of BS <NUM> may use the indication of the quantity, the indication of the respective identifiers, and the indication of the respective lengths, to identify the subset of MAC sub-PDUs that are to be decrypted and/or integrity checked.

In some aspects, the information associated with MAC security for the MAC PDU may include a MAC security sequence number associated with the MAC PDU communication. The MAC security sequence number may be particular to the MAC PDU communication and may be sequentially incremented for the transmission of each subsequent MAC PDU communication. If UE <NUM> and/or the DU of BS <NUM> receives a MAC PDU and determines that the MAC security sequence is not incremented or out of sequence relative to a previously received MAC PDU communication, UE <NUM> and/or the DU of BS <NUM> may disregard the MAC PDU communication and/or transmit an instruction for retransmission of the MAC PDU communication. In this way, if a potentially malicious entity intercepts a MAC PDU communication between UE <NUM> and the DU of BS <NUM> and tries to use the MAC PDU communication for a malicious purpose, the receiver of the MAC PDU communication (e.g., UE <NUM> or the DU of BS <NUM>) may prevent the malicious purpose by first inspecting the MAC security sequence number.

In some aspects, UE <NUM> and/or BS <NUM> may further implement MAC security for the MAC PDU communication by decrypting or encrypting the MAC PDU communication using the KMECEnc or KDUEnc associated with the DU of BS <NUM>, by integrity protecting the MAC PDU communication using the KMACInt or KDUInt associated with the DU of BS <NUM>, and/or the like. For example, a transmitter of the MAC PDU communication (e.g., UE <NUM> or BS <NUM>) may encrypt the MAC PDU communication (e.g., based at least in part on the indicated MAC security configuration) by using KMACEnc or KDUEnc in an encryption algorithm, such as an encryption algorithm specified in 3GPP TS <NUM> D. If KDUEnc is used in the encryption algorithm, the transmitter may include a MAC encryption input parameter (e.g., a value that is specific to MAC encryption) in the encryption algorithm to distinguish the encryption of the MAC PDU from encryption that is used for RRC communications. The transmitter may use the encryption algorithm to generate a keystream block, for each protected MAC sub-PDU, and may generate a cyphertext block from a plaintext block for each MAC sub-PDU based at least in part on a corresponding keystream block.

As another example, the transmitter may integrity protect the MAC PDU communication (e.g., based at least in part on the indicated MAC security configuration) by using KMACInt or KDUInt in an integrity protection algorithm, such as an integrity protection specified in 3GPP TS <NUM> D. If KDUInt is used in the integrity protection algorithm, the transmitter may include a MAC integrity protection input parameter (e.g., a value that is specific to MAC integrity protection) in the integrity protection algorithm to distinguish the integrity protection of the MAC PDU communication from integrity protection that is used for RRC communications. The transmitter may generate a message authentication code using the integrity protection algorithm, and may append the message authentication code to the MAC PDU.

The receiver may receive the MAC PDU and may decrypt the MAC PDU communication (e.g., based at least in part on the indicated MAC security configuration) by using KMACEnc or KDUEnc in a decryption algorithm, such as a decryption algorithm specified in 3GPP TS <NUM> D. If KDUEnc is used in the decryption algorithm, the receiver may include the MAC encryption input parameter in the decryption algorithm. The receiver may use the decryption algorithm to generate a keystream block, for each protected MAC sub-PDU, and may generate a plaintext block from a cyphertext block for each MAC sub-PDU based at least in part on a corresponding keystream block.

As another example, the receiver may integrity check the MAC PDU communication (e.g., based at least in part on the indicated MAC security configuration) by using KMACInt or KDUInt in an integrity protection algorithm, such as an integrity protection algorithm specified in 3GPP TS <NUM> D. If KDUInt is used in the integrity protection algorithm, the receiver may include the MAC integrity protection input parameter in the integrity protection algorithm. The receiver may generate a message authentication code using the integrity protection algorithm, and may compare the generated message authentication code with the message authentication code that is appended to the MAC PDU to determine whether the generated message authentication code is an exact match of the message authentication code.

In this way, UE <NUM> may transmit, to BS <NUM>, an indication of a MAC security capability of UE <NUM>. BS <NUM> may transmit, to UE <NUM>, an indication of a MAC security configuration for communications between UE <NUM> and BS <NUM>. The MAC security configuration may be based at least in part on the UE <NUM>'s MAC security capability, and may indicate a level of MAC security that is to be used when encrypting, decrypting, and/or integrity protecting MAC PDUs transmitted between UE <NUM> and BS <NUM>. Moreover, UE <NUM> and BS <NUM> may generate various keys that may be used when encrypting, decrypting, and/or integrity protecting MAC PDUs transmitted between UE <NUM> and BS <NUM>. In this way, UE <NUM> and BS <NUM> may implement MAC security for MAC PDUs transmitted between UE <NUM> and BS <NUM>, which increases the security of the MAC PDUs, prevents performance degradations and attacks of the MAC PDUs, and/or the like.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a UE (e.g., UE <NUM>) performs MAC security.

As shown in <FIG>, process <NUM> may include transmitting, to a BS, information indicating a MAC security capability of the UE (block <NUM>). For example, the UE (e.g., transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may transmit, to a base station (BS), information indicating a MAC security capability of the UE, as described above.

As further shown in <FIG>, process <NUM> may include receiving, from the BS, a communication that includes an indication of a MAC security configuration for communications between the UE and the BS, wherein the indication of the MAC security configuration is based at least in part on the MAC security capability of the UE (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may receive, from the BS, a communication that includes an indication of a MAC security configuration for communications between the UE and the BS, as described above. In some aspects, the indication of the MAC security configuration is based at least in part on the MAC security capability of the UE.

Process <NUM> may include additional aspects, such as any single implementation or any combination of aspects described below and/or in connection with one or more other processes described elsewhere herein.

In a first aspect, the indication of the MAC security configuration comprises an indication that MAC security is to be used for an entire MAC PDU transmitted between the UE and the BS, an indication that MAC security is to be used for all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE, or an indication that MAC security is to be used for a subset of the MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a second aspect, alone or in combination with the first aspect, the communication includes one or more parameters unique to a DU of the BS, and process <NUM> comprises generating, based at least in part on the one or more parameters unique to the DU, a DU key to be used for communications between the UE and the DU.

In a third aspect, alone or in combination with one or more of the first or second aspects, generating the DU key comprises generating the DU key based at least in part on a BS key associated with the BS. In some aspects, generating the DU key comprises using the one or more parameters unique to the DU and the BS key in a key derivation function. In a fourth aspect, alone or in combination with one or more of the first through third aspects, the one or more parameters unique to the DU comprises at least one of a PCI associated with the DU, a random number that is randomly generated by the DU, or an alphanumeric string. In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, process <NUM> comprises generating, based at least in part on the DU key, a MAC encryption key associated with the DU and a MAC integrity key associated with the DU.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, process <NUM> comprises generating, based at least in part on the DU key, an RRC encryption key associated with the DU, an RRC integrity key associated with the DU, a MAC encryption key associated with the DU, and a MAC integrity key associated with the DU. In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, process <NUM> comprises generating, based at least in part on the DU key, a DU encryption key associated with the DU and a DU integrity key associated with the DU. In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, process <NUM> comprises decrypting an( RRC communication, received from the DU, based at least in part on a decryption algorithm in which the DU encryption key and an RRC input parameter is used, or encrypting a RRC communication, to be transmitted to the DU, based at least in part on an encryption algorithm in which the DU encryption key and the RRC input parameter is used.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, process <NUM> comprises decrypting a MAC PDU communication, received from the DU, based at least in part on a decryption algorithm in which the DU encryption key and a MAC input parameter is used, or encrypting a MAC PDU communication, to be transmitted to the DU, based at least in part on an encryption algorithm in which the DU encryption key and the MAC input parameter is used.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, process <NUM> comprises generating a message authentication code based at least in part on an integrity algorithm in which the DU integrity key and an RRC input parameter is used. In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, process <NUM> comprises generating a message authentication code based at least in part on an integrity algorithm in which the DU integrity key and a MAC input parameter is used. In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, process <NUM> comprises receiving, from the BS, a MAC PDU, identifying a MAC security CE included in the MAC PDU, and identifying, based at least in part on the MAC security configuration, information, associated with MAC security of the MAC PDU, included in the MAC security CE.

In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, the information associated with the MAC security of the MAC PDU comprises a MAC security sequence number associated with the MAC PDU. In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a quantity of all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE and an indication of a combined length of all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE.

In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for an entire MAC PDU transmitted between the UE and the BS. In a seventeenth aspect, alone or in combination with one or more of the first through sixteenth aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a length of the MAC PDU. In an eighteenth aspect, alone or in combination with one or more of the first through seventeenth aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for a subset of MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a nineteenth aspect, alone or in combination with one or more of the first through eighteenth aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a quantity of MAC sub-PDUs included in the subset of MAC sub-PDUs and an indication of a respective length of each MAC sub-PDU included in the subset of MAC sub-PDUs.

In a twentieth aspect, alone or in combination with one or more of the first through nineteenth aspects, process <NUM> comprises generating, for transmission to the BS, a MAC PDU, and configuring, based at least in part on the MAC security configuration, a MAC security CE included in the MAC PDU, wherein the MAC security CE includes information associated with MAC security of the MAC PDU. In a twenty-first aspect, alone or in combination with one or more of the first through twentieth aspects, the information associated with the MAC security of the MAC PDU comprises a MAC security sequence number associated with the MAC PDU.

In a twenty-second aspect, alone or in combination with one or more of the first through twenty-first aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a twenty-third aspect, alone or in combination with one or more of the first through twenty-second aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a quantity of all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE and an indication of a combined length of all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a twenty-fourth aspect, alone or in combination with one or more of the first through twenty-third aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for an entire MAC PDU transmitted between the UE and the BS. In a twenty-fifth aspect, alone or in combination with one or more of the first through twenty-fourth aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a length of the MAC PDU.

In a twenty-sixth aspect, alone or in combination with one or more of the first through twenty-fifth aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for a subset of MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a twenty-seventh aspect, alone or in combination with one or more of the first through twenty-sixth aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a quantity of MAC sub-PDUs included in the subset of MAC sub-PDUs and an indication of a respective length of each MAC sub-PDU included in the subset of MAC sub-PDUs.

In a twenty-eighth aspect, alone or in combination with one or more of the first through twenty-seventh aspects, receiving the communication comprises receiving the communication based at least in part on a handover being initiated between a first DU and a second DU. In a twenty-ninth aspect, alone or in combination with one or more of the first through twenty-eighth aspects, the second DU is associated with the BS and the first DU is associated with the BS or another BS. In a thirtieth aspect, alone or in combination with one or more of the first through twenty-ninth aspects, the communication includes an indication to generate a DU key associated with the first DU. In some a thirty-first aspect, alone or in combination with one or more of the first through thirtieth aspects, process <NUM> comprises generating the DU key associated with the first DU based at least in part on the indication to generate the DU key associated with the first DU.

In a thirty-second aspect, alone or in combination with one or more of the first through thirty-first aspects, the handover is an Xn-based handover. In a thirty-third aspect, alone or in combination with one or more of the first through thirty-second aspects, process <NUM> comprises generating a BS key associated with a BS that is associated with the first DU, and generating a DU key, associated with the first DU, based at least in part on the BS key. In a thirty-fourth aspect, alone or in combination with one or more of the first through thirty-third aspects, the communication comprises an RRC reconfiguration communication.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a BS, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a BS (e.g., BS <NUM>) performs MAC security.

As shown in <FIG>, process <NUM> may include receiving, from a UE, information indicating a MAC security capability of the UE (block <NUM>). For example, the BS (e.g., using receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may receive, from a UE, information indicating a MAC security capability of the UE, as described above.

As further shown in <FIG>, process <NUM> may include transmitting, to the UE, a communication that includes an indication of a MAC security configuration for communications between the UE and the BS, wherein the indication of the MAC security configuration is based at least in part on the MAC security capability of the UE (block <NUM>). For example, the BS (e.g., using transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may transmit, to the UE, a communication that includes an indication of a MAC security configuration for communications between the UE and the BS, as described above. In some aspects, the indication of the MAC security configuration is based at least in part on the MAC security capability of the UE.

In a first aspect, the indication of the MAC security configuration comprises an indication that MAC security is to be used for an entire MAC PDU transmitted between the UE and the BS, an indication that MAC security is to be used for all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE, or an indication that MAC security is to be used for a subset of the MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE.

In a second aspect, alone or in combination with the first aspect, the communication includes one or more parameters unique to a DU of the BS. In a third aspect, alone or in combination with one or more of the first or second aspects, process <NUM> comprises generating, based at least in part on the one or more parameters unique to the DU, a DU key to be used for communications between the UE and the DU. In some aspects, generating the DU key comprises generating the DU key based at least in part on a BS key associated with the BS. In a fourth aspect, alone or in combination with one or more of the first through third aspects, generating the DU key comprises using the one or more parameters unique to the DU and the BS key in a key derivation function.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the one or more parameters unique to the DU comprises at least one of a PCI associated with the DU, a random number that is randomly generated by the DU, or an alphanumeric string. In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, process <NUM> comprises generating, based at least in part on the DU key, a MAC encryption key associated with the DU and a MAC integrity key associated with the DU. In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, process <NUM> comprises generating, based at least in part on the DU key, an RRC encryption key associated with the DU, an RRC integrity key associated with the DU, a MAC encryption key associated with the DU, and a MAC integrity key associated with the DU.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, process <NUM> comprises generating, based at least in part on the DU key, a DU encryption key associated with the DU and a DU integrity key associated with the DU. In a ninth aspect, alone or in combination with one or more of the first through third aspects, process <NUM> comprises decrypting an RRC communication, received from the DU, based at least in part on a decryption algorithm in which the DU encryption key and an RRC input parameter is used, or encrypting a RRC communication, to be transmitted to the DU, based at least in part on an encryption algorithm in which the DU encryption key and the RRC input parameter is used.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, process <NUM> comprises decrypting a MAC PDU communication, received from the DU, based at least in part on a decryption algorithm in which the DU encryption key and a MAC input parameter is used, or encrypting a MAC PDU communication, to be transmitted to the DU, based at least in part on an encryption algorithm in which the DU encryption key and the MAC input parameter is used. In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, process <NUM> comprises generating a message authentication code based at least in part on an integrity algorithm in which the DU encryption key and an RRC input parameter is used.

In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, generating a message authentication code based at least in part on an integrity algorithm in which the DU encryption key and a MAC input parameter is used. In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, process <NUM> comprises receiving, from the UE, a MAC PDU, identifying a MAC security CE included in the MAC PDU, and identifying, based at least in part on the MAC security configuration, information, associated with MAC security of the MAC PDU, included in the MAC security CE.

In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, the information associated with the MAC security of the MAC PDU comprises a MAC security sequence number associated with the MAC PDU. In a fifteenth aspect, alone or in combination with one or more of the first through fourteenth aspects, the indication of the MAC security configuration comprise an indication that MAC security is to be used for all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a sixteenth aspect, alone or in combination with one or more of the first through fifteenth aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a quantity of all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE and an indication of a combined length of all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE.

In a seventeenth aspect, alone or in combination with one or more of the first through sixteenth aspects, the indication of the MAC security configuration comprise an indication that MAC security is to be used for an entire MAC PDU transmitted between the UE and the BS. In an eighteenth aspect, alone or in combination with one or more of the first through seventeenth aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a length of the MAC PDU. In a nineteenth aspect, alone or in combination with one or more of the first through eighteenth aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for a subset of MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a twentieth aspect, alone or in combination with one or more of the first through nineteenth aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a quantity of MAC sub-PDUs included in the subset of MAC sub-PDUs and an indication of a respective length of each MAC sub-PDU included in the subset of MAC sub-PDUs.

In a twenty-first aspect, alone or in combination with one or more of the first through twentieth aspects, process <NUM> comprises generating, for transmission to the UE, a MAC PDU, configuring, based at least in part on the MAC security configuration, a MAC security CE included in the MAC PDU, wherein the MAC security CE includes information associated with MAC security of the MAC PDU. In a twenty-second aspect, alone or in combination with one or more of the first through twenty-first aspects, the information associated with the MAC security of the MAC PDU comprises a MAC security sequence number associated with the MAC PDU.

In a twenty-third aspect, alone or in combination with one or more of the first through twenty-second aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a twenty-fourth aspect, alone or in combination with one or more of the first through twenty-third aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a quantity of all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE and an indication of a combined length of all MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a twenty-fifth aspect, alone or in combination with one or more of the first through twenty-fourth aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for an entire MAC PDU transmitted between the UE and the BS. In a twenty-sixth aspect, alone or in combination with one or more of the first through twenty-fifth aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a length of the MAC PDU.

In a twenty-seventh aspect, alone or in combination with one or more of the first through twenty-sixth aspects, the indication of the MAC security configuration comprises an indication that MAC security is to be used for a subset of MAC sub-PDUs, included in the MAC PDU, that include a MAC-CE. In a twenty-eighth aspect, alone or in combination with one or more of the first through twenty-seventh aspects, the information associated with the MAC security of the MAC PDU comprises an indication of a quantity of MAC sub-PDUs included in the subset of MAC sub-PDUs and an indication of a respective length of each MAC sub-PDU included in the subset of MAC sub-PDUs. In a twenty-ninth aspect, alone or in combination with one or more of the first through twenty-eighth aspects, transmitting the communication comprises transmitting the communication based at least in part on a handover being initiated between a first DU and a second DU.

In a thirtieth aspect, alone or in combination with one or more of the first through twenty-ninth aspects, the first DU is associated with the BS and the second DU is associated with the BS or another BS. In a thirty-first aspect, alone or in combination with one or more of the first through thirtieth aspects, the communication includes an indication to generate a DU key associated with the first DU. In a thirty-second aspect, alone or in combination with one or more of the first through thirty-first aspects, process <NUM> comprises generating the DU key associated with the first DU. In some aspects, the handover is an Xn-based handover. In a thirty-third aspect, alone or in combination with one or more of the first through thirty-second aspects, process <NUM> comprises generating a BS key and generating a DU key, associated with the first DU, based at least in part on the BS key. In a thirty-fourth aspect, alone or in combination with one or more of the first through thirty-third aspects, the communication comprises an RRC reconfiguration communication.

Claim 1:
A method (<NUM>) of wireless communication performed by a user equipment, UE, the method (<NUM>) comprising:
transmitting (<NUM>), to a base station, BS, information indicating a medium access control, MAC, security capability of the UE; and
receiving (<NUM>), from the BS, a communication that includes an indication of a MAC security configuration for communications between the UE and the BS,
wherein the indication of the MAC security configuration is based at least in part on the MAC security capability of the UE;
generating a distributed unit, DU, key from a BS key based at least in part on the communication;
generating a MAC encryption key and a MAC integrity key from the DU key; and
using the MAC encryption key or the MAC integrity key to communicate with the BS.