To enable more efficient buffer reuse for HMAC operations three new
functions have been introduced. This change prevents the need to
reallocate memory for each HMAC operation:
- grub_crypto_hmac_reset(): reinitializes the hash contexts in the HMAC handle,
- grub_crypto_hmac_final(): provides the final HMAC result without freeing the
handle allowing it to be reused immediately,
- grub_crypto_hmac_free(): deallocates the HMAC handle and its associated memory.
To further facilitate buffer reuse ctx2 is now included within the HMAC handle
struct and the initialization of ctx2 is moved to grub_crypto_hmac_init().
The intermediate hash states, ctx and ctx2, for the inner and outer padded
keys are now cached. The grub_crypto_hmac_reset() restores these cached
states for new operations which avoids redundant hashing of the keys.
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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