z/OS-based master-key verification method

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When the first and third portions of the symmetric master key have the same value, the master key is effectively a double-length DES key.

In this case, the master-key verification pattern (MKVP) is based on this algorithm:
  • C = X'4545454545454545'
  • IR = MKfirst-part XOR eC(MKfirst-part)
  • MKVP = MKsecond-part XOR eIR(MKsecond-part)
where:
  • ex(Y) is the DES encoding of Y using x as a key
  • XOR means bitwise exclusive OR

Version X'00' internal CCA DES key tokens use this eight-byte master-key verification pattern.