Integrity of PKA private key sections containing an encrypted RSA key

With the exception of RSA key tokens containing an AES encrypted OPK (sections X'30' and X'31'), if an RSA key-token contains information for an encrypted private-key, then the integrity of the information within the token can be verified by computing and comparing the SHA-1 message digest values that are found at offsets 4 and 30 within the private-key section.

The SHA-1 message digest at offset 4 requires access to the cleartext values of the private-key components. The cryptographic engine verifies this hash quantity whenever it retrieves the secret key for productive use.

A second SHA-1 message digest, located at offset 30 (excluding sections X'30' and X'31'), is computed on optional, designated key-token information following the public-key section. The value of this SHA-1 message digest is included in the computation of the message digest at offset 4. As with the offset 4 value, the message digest at offset 30 is validated whenever a private key is recovered from the token for productive use.

CCA provides PKA private key sections X'30' and X'31'. These sections can contain an AESKW-wrapped (ANS X9.102) RSA private key (wrapped by the OPK) and an AES encrypted OPK. When the RSA key with an AES encrypted OPK is wrapped, a message digest is calculated over the associated data section contained in the private-key section. The calculated message digest becomes part of the payload before it is wrapped. There is no way for a user to retrieve this value to validate it. The same is true for ECC private keys, which are AESKW-wrapped.

In addition to the hash checks, various token-format and content checks are performed to validate the key values.

The optional PKA private-key name section can be used by access-monitor systems to ensure that the application program is entitled to employ the particular private key.