# US 12,764,524 B2 · Method and apparatus for security of a wireless communication > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,764,524 B2 - Document ID: US12764524B2 - Status: Granted - Kind: B2 - Application number: 18/446,408 - Filed: 2023-08-08 - Published: 2024-02-15 - Granted: 2026-10-13 - Earliest claimed: 2022-08-09 - Assignees: Nokia Technologies Oy - Applicants: Nokia Technologies Oy - Inventors: Benoist Pierre Sebire; Peter Schneider - Web page: https://patentgrep.com/patent/US12764524B2 ## CPC - H04W 12/03: Protecting confidentiality, e.g. by encryption - H04L 9/0618: {Block ciphers, i.e. encrypting groups of characters of a plain text message using fixed encryption transformation} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Methods and apparatus are disclosed for security of a wireless communication between a communication device and a counterpart communication device. A method performed at the communication device comprises, ciphering a fixed part of a medium access control (MAC) protocol data unit (PDU) at MAC layer for the wireless communication. The fixed part of the MAC PDU comprises at least one of the following fields: at least one MAC control element, or at least one header of radio protocol in the MAC PDU. ## Claims ### Claim 1 An apparatus at a communication device for security of a wireless communication between the communication device and a counterpart communication device, the 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 perform: cipher a fixed part of a medium access control (MAC) protocol data unit (PDU) at MAC layer for the wireless communication, wherein a size of the fixed part of the MAC PDU is a size that matches a block size of a block cipher that is applied to encrypt the fixed part or a multiple of the block size of the block cipher, wherein parts of the MAC PDU other than the fixed part are not ciphered at the MAC layer, and wherein, the fixed part of the MAC PDU comprises the following fields: at least one MAC control element, and at least one header of radio protocol. ### Claim 2 A method performed at a communication device for security of a wireless communication between the communication device and a counterpart communication device, the method comprising: ciphering, at the communication device, a fixed part of a medium access control (MAC) protocol data unit (PDU) at MAC layer for the wireless communication, wherein a size of the fixed part of the MAC PDU is a size that matches a block size of a block cipher that is applied to encrypt the fixed part or a multiple of the block size of the block cipher, wherein parts of the MAC PDU other than the fixed part are not ciphered at the MAC layer, and wherein, the fixed part of the MAC PDU comprises of the following fields: at least one MAC control element, and at least one header of radio protocol in the MAC PDU. ### Claim 3 (depends on 2) The method according to claim 2, wherein the at least one header of radio protocol comprises at least one of: one or more MAC subheaders of MAC service data units (SDUs) included in the MAC PDU; one or more radio link control (RLC) headers; or one or more packet data convergence protocol (PDCP) headers. ### Claim 4 (depends on 2) The method according to claim 2, further comprising: determining how to build the MAC PDU, based on the size of the fixed part of the MAC PDU, or based on a location of the fixed part within the MAC PDU, or based on the size of the fixed part of the MAC PDU and a location of the fixed part within the MAC PDU. ### Claim 5 (depends on 4) The method according to claim 4, wherein determining how to build the MAC PDU comprises determining how to build the MAC PDU according to at least one of the following principles: in case that there are a plurality of MAC control elements to be included in the MAC PDU, one or more MAC control elements of the plurality of MAC control elements is placed outside the fixed part, or is postponed to a next MAC PDU; in case that there are a plurality of MAC control elements to be included in the fixed part, an order in which the plurality of MAC control elements are included in the fixed part is randomized; in case that there are a plurality of MAC SDUs to be included in the MAC PDU, subheaders of respective MAC SDUs are concatenated at the beginning or end of the MAC PDU; in case that there are a plurality of MAC SDUs to be included in the MAC PDU, an order in which the plurality of MAC SDUs are included in the MAC PDU changes from one MAC PDU to another MAC PDU; in case that there are padding bits to be included in the fixed part, the padding bits are randomized bits; or one or more MAC control elements of the MAC PDU to be ciphered are placed in the fixed part at the beginning or the end of the MAC PDU, while the other MAC control elements of the MAC PDU are placed at an opposite side of the MAC PDU. ### Claim 6 (depends on 2) The method according to claim 2, wherein the fixed part of the MAC PDU is started with a random nonce. ### Claim 7 (depends on 2) The method according to claim 2, wherein the fixed part of the MAC PDU comprises a MAC control element (MAC CE) with random content. ### Claim 8 (depends on 2) The method according to claim 2, further comprising: obtaining an indication of the size of the fixed part of the MAC PDU; or obtaining an indication of one or more candidate sizes of the fixed part, and selecting one candidate size as the size of the fixed part of the MAC PDU. ### Claim 9 (depends on 8) The method according to claim 8, wherein, obtaining the indication of the size of the fixed part of the MAC PDU comprises receiving by the communication device, an indication of the size of the fixed part of the MAC PDU; or obtaining the indication of one or more candidate sizes of the fixed part of the MAC PDU comprises receiving by the communication device, an indication of one or more candidate sizes of the fixed part, and selecting one candidate size as the size of the fixed part of the MAC PDU. ### Claim 10 (depends on 8) The method according to claim 8, wherein the obtained indication comprises at least one of the following: a capability parameter of the communication device, which indicates one or more candidate sizes of the fixed part of the MAC PDU supported by the communication device; or a capability parameter of the counterpart communication device, which indicates one or more candidate sizes of the fixed part of the MAC PDU supported by the counterpart communication device. ### Claim 11 (depends on 2) The method according to claim 2, further comprising: sending to the counterpart communication device, an indication of the size of the fixed part of the MAC PDU; or sending to the counterpart communication device, an indication of one or more candidate sizes of the fixed part of the MAC PDU. ### Claim 12 (depends on 11) The method according to claim 11, wherein the sent indication comprises: a capability parameter of the communication device, which indicates one or more candidate sizes of the fixed part of the MAC PDU supported by the communication device. ### Claim 13 (depends on 2) The method according to claim 2, further comprising: delivering the ciphered MAC PDU to a physical layer for transmission to a counterpart communication device.