Customized HMAC key (PKEY)

The HMAC keyed hash algorithm is different in the sense that OpenSSL does not define any specific type for it like it does for many of the other algorithms. Instead, it requires a custom EVP_PKEY_METHOD implementation. This is what the BCrypt EVP engine does; it supports HMAC with the digests enumerated in Message digests (MD).

To use this algorithm, use the EVP_PKEY_new_raw_private_key function with the EVP_PKEY_HMAC type. For examples, see the test_bcrypt_hmac_sha.cpp which contains its associated functional tests.

Control commands

There are no control commands for the custom HMAC key.

Known issues or limitations

This algorithm has no know issues or limitations.