ISO 16609 TDES MAC

ISO 16609 defines a process for protecting the integrity of transmitted banking messages and for verifying that a message has originated from an authorized source and this process is called the ISO 16609 TDES MAC method.

The ISO 16609 TDES MAC method corresponds to ISO/IEC 9797-1, algorithm 1 using T-DEA (ANSI X9.52:1998). ISO/FDIS 16609 identifies this method as one of the recommended ways to generate a MAC using symmetric techniques.

The ISO 16609 TDES MAC method uses a double-length DES key and operates on data blocks that are a multiple of eight bytes. If the last input data block is not a multiple of eight bytes, binary zeros are appended to the right of the block. A CBC mode triple-DES (TDES) encryption operation is performed on the data, with all output discarded except for the final output block.

The resulting MAC value is processed according to other specifications supplied to the verb call.