PKCS#11
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| Cryptographic Token Interface Standard |
PKCS#11 |
The PKCS #3 Diffie-Hellman key derivation mechanism, denoted CKM_DH_PKCS_DERIVE, is a mechanism for key derivation based on Diffie-Hellman key agreement, as defined in PKCS #3. This is what PKCS #3 calls "phase II".
It has a parameter, which is the public value of the other party in the key agreement protocol, represented as a Cryptoki "Big integer" (i.e., a sequence of bytes, most-significant byte first).
This mechanism derives a secret key from a Diffie-Hellman private key and the public value of the other party. It computes a Diffie-Hellman secret value from the public value and private key according to PKCS #3, and truncates the result according to the CKA_KEY_TYPE attribute of the template and, if it has one and the key type supports it, the CKA_VALUE_LEN attribute of the template. (The truncation removes bytes from the leading end of the secret value.) The mechanism contributes the result as the CKA_VALUE attribute of the new key; other attributes required by the key type must be specified in the template.
This mechanism has the following rules about key sensitivity and extractability
Note that the rules regarding the CKA_SENSITIVE, CKA_EXTRACTABLE, CKA_ALWAYS_SENSITIVE, and CKA_NEVER_EXTRACTABLE attributes have changed in version 2.11 to match the policy used by other key derivation mechanisms such as CKM_SSL3_MASTER_KEY_DERIVE.