| 摘要 |
PROBLEM TO BE SOLVED: To enhance the use of a tbox function for CMEA encryption. SOLUTION: Offsets are generated for inputting a message to the tbox function by using secret values and previously encrypted message octets. The offset are used to permute the message for application of the tbox function. For the first message of a call, the previously encrypted message octets are replaced by an initialization value. In a system employing a single iteration of CMEA encryption, first and second offsets are generated. In a system employing two iterations of CMEA encryption, the first, second, third, and fourth offsets are generated, with the first and second offsets being used in the first iteration of CMEA encryption and the third and fourth offsets being used in the second iteration of CMEA encryption. COPYRIGHT: (C)2003,JPO |
