Secure Communication Method and Apparatus

{
  "publication_number": "US2026106697A1",
  "country": "US",
  "kind": "A1",
  "title": "Secure Communication Method and Apparatus",
  "abstract": "In a secure communication method, a terminal device receives downlink control information, where the downlink control information indicates whether the k th piece of data transmitted in the i th hybrid automatic repeat request (HARQ) process is newly transmitted. If the k th piece of data is newly transmitted, a random seed is updated. An updated random seed is used for security processing on the k th piece of data. Based on this solution, a network device indicates, to the terminal device by using the downlink control information, whether the scheduled k th piece of data is newly transmitted. When the k th piece of data is newly transmitted, the terminal device may update the random seed, thereby synchronizing the random seed with the network device.",
  "claims": [
    "1. A method, comprising: receiving downlink control information indicating whether a k th piece of data transmitted in an i th hybrid automatic repeat request (HARQ) process is newly transmitted, wherein i identifies a HARQ process number; and updating a first random seed to obtain an updated first random seed when the k th piece is newly transmitted, wherein the updated first random seed is for security processing on the k th piece. 2. The method of claim 1, wherein an identifier of the i th HARQ process is associated with an i th security system. 3. The method of to claim 1, wherein updating the first random seed comprises updating, based on a (k−1) th piece of data and a second random seed, the first random seed, wherein the second random seed is for security processing on the (k−1) th piece, and wherein the (k−1) th piece is successfully transmitted in the i th HARQ process. 4. The method of claim 1, wherein the downlink control information comprises a new data indicator (NDI), wherein a toggle in the NDI indicates that the k th piece is newly transmitted, and wherein no toggle in the NDI indicates that the k th piece is retransmitted. 5. The method of claim 3, wherein before receiving the downlink control information, the method further comprises: receiving the (k−1) th piece in the i th HARQ process; performing, based on the second random seed, inverse security processing on the (k−1) th piece; and sending response information of the (k−1) th piece indicating that the (k−1) th piece is successfully transmitted. 6. The method of claim 1, further comprising: performing, based on the updated first random seed, security processing on the k th piece to obtain a processed k th piece of security data; and sending the processed k th piece when the downlink control information indicates that the k th piece is newly transmitted. 7. The method of claim 1, further comprising decrypting, based on a second random seed, the downlink control information when a part of or all fields in the downlink control information are encrypted, and wherein updating the first random seed comprises updating, based on the second random seed, the first random seed. 8. The method of claim 7, wherein the downlink control information comprises the HARQ process number, and wherein the HARQ process number is not encrypted. 9. The method of claim 1, wherein updating the first random seed comprises: receiving an initialized random bit when a quantity of retransmissions of a transport block in the i th HARQ process is greater than or equal to a preset threshold and when the k th piece is newly transmitted; updating, based on the initialized random bit, the first random seed; and resetting the quantity to a specified value. 10. The method of claim 9, wherein the quantity comprises a first cumulative count of retransmissions for all transport blocks corresponding to the i th HARQ process, or wherein the quantity comprises a second cumulative count of retransmissions for a specific transport block in the i th HARQ process. 11. A method, comprising: receiving response information of a (k−1) th piece of data transmitted in an i th hybrid automatic repeat request (HARQ) process, wherein the response information indicates that the (k−1) th piece is successfully transmitted, or receiving the (k−1) th piece in the i th HARQ process, and successfully decoding the (k−1) th piece; updating a first random seed to obtain an updated first random seed, wherein the updated first random seed is for security processing on a k th piece of data transmitted in the i th HARQ process; and sending downlink control information indicating that the k th piece is newly transmitted. 12. The method of claim 11, wherein an identifier of the i th HARQ process is associated with an i th security system. 13. The method of claim 11, wherein updating the first random seed comprises updating, based on the (k−1) th piece and a second random seed, the first random seed, wherein the second random seed is for security processing on the (k−1) th piece, and wherein the (k−1) th piece is successfully transmitted in the i th HARQ process. 14. The method of claim 11, wherein the downlink control information comprises a new data indicator (NDI), wherein a toggle in the NDI indicates that the k th piece is newly transmitted, and wherein no toggle in the NDI indicates that the k th piece is retransmitted. 15. The method of claim 13, wherein before receiving the response information, the method further comprises: performing, based on the second random seed, security processing on the (k−1) th piece to obtain a processed (k−1) th piece of security data; and sending the processed (k−1) th piece. 16. The method of claim 11, further comprising: receiving the k th piece when the downlink control information indicates that the k th piece is newly transmitted; and performing, based on the updated first random seed, inverse security processing on the k th piece. 17. The method of claim 13, further comprising decrypting, based on the second random seed, the downlink control information when a part of or all fields in the downlink control information are encrypted. 18. The method of claim 17, wherein the downlink control information comprises a HARQ process number of the i th HARQ process, and wherein the HARQ process number is not encrypted. 19. The method of claim 11, wherein updating the first random seed comprises: updating, based on an initialized random bit, the first random seed when a quantity of retransmissions of a transport block in the i th HARQ process is greater than or equal to a preset threshold; sending the initialized random bit; and resetting the quantity to a specified value. 20. The method of claim 19, wherein the quantity comprises a first cumulative count of retransmissions for all transport blocks corresponding to the i th HARQ process, or wherein the quantity comprises a second cumulative count of retransmissions for a specific transport block in the i th HARQ process. 21. A communication apparatus, comprising: a memory configured to store instructions; and one or more processors coupled to the memory and configured to execute the instructions to cause the communication apparatus to: receive downlink control information indicating whether a k th piece of data transmitted in an i th hybrid automatic repeat request (HARQ) process is newly transmitted, wherein i identifies a HARQ process number; and update a first random seed to obtain an updated first random seed when the k th piece is newly transmitted, wherein the updated first random seed is for security processing on the k th piece of data. 22. A communication apparatus, comprising: a memory configured to store instructions; and one or more processors coupled to the memory and configured to execute the instructions to cause the communication apparatus to: receive response information of a (k−1) th piece of data transmitted in an i th hybrid automatic repeat request (HARQ) process, wherein the response information indicates that the (k−1) th piece is successfully transmitted, or receiving the (k−1) th piece in the i th HARQ process, and successfully decoding the (k−1) th piece; update a first random seed to obtain an updated first random seed, wherein the updated first random seed is for security processing on a k th piece of data transmitted in the i th HARQ process; and send downlink control information indicating that the k th piece is newly transmitted."
  ],
  "cpc": [
    "H04L 1/1812",
    "H04W 12/03",
    "H04W 72/231"
  ],
  "filing_date": "2025-12-16",
  "publication_date": "2026-04-16",
  "application_number": "US-202519421464-A"
}