Key attribute verification

A key identifier that identifies a cryptographic key is transmitted to a cryptographic coprocessor. A first set of attributes is received from the cryptographic coprocessor. The first set of attributes and a second set of attributes are serialized into a first sequence of attributes. The first sequence of attributes are stored to an attribute frame. One or more attributes in the second set of attributes are associated with the cryptographic key and originate from a key attribute storage of the key management system. The second set of attributes is different from the first set of attributes. The first sequence of attributes is transmitted to the cryptographic coprocessor. A first message authentication code (MAC) calculated from the first sequence of attributes is received from the cryptographic coprocessor. The attribute frame is verified by comparing the first MAC, or a value derived from the first MAC, to a reference value.