| 摘要 |
An authenticator device designed to preclude undetected compensating text modifications in a message by sequentially processing each character of the message and producing an authenticator code as a result of said processing. As each message is received, it is modulo added to the contents of a first register and the result is used to simultaneously address first and second memories, the values stored in the first memory consisting of a specified permutation of preselected decimal values, the values stored in the second memory consisting of non-linear transformations of a 16 digit authentication key. The data read out of the second memory is used to address a third memory, the values stored in the third memory consisting of another specified permutation of preselected decimal values. The data read out of the third memory replaces the value previously stored in the first register. The data read out of the first memory is modulo added into a shift register, which after the addition is circularly shifted a fixed number of bit positions. The same processing is repeated for each character of the message text, after which the residue remaining in the shift register is available for use as the authenticator code.
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