Manner and device null of the security expansion where the secret key to the look-up table in order to improve the security of radio telephone message is strengthened

摘要

(57) use of tbox function for [summary] CMEA encryption is strengthened. Generating an offset for using the message octets are encrypted before and secret value, and inputs the message to the tbox function. To replace the message by using the offset, to enter into tbox function. For the first message of a call, the message octets are encrypted before being replaced by the initial value. In systems using a CMEA encryption only once, to produce an offset first and second. In systems using a CMEA encryption of two, to generate the offset of the first, second, and third, and the second offset first used in CMEA encryption of the first, third and The fourth offset used in CMEA encryption second.