Control vector

A unique control vector exists for each type of CCA key.

For an internal key token, the coprocessor XORs the master key with the control vector associated with the type of key the master key will encipher. The control vector ensures that an operational key is used only in cryptographic functions for which it is intended. For example, the control vector for an input PIN-encrypting key ensures that such a key can be used only in the Encrypted PIN Translate and Encrypted PIN Verify functions.