All TLS cipher types use a common structure for the per-record data
that is authenticated in addition to the plaintext itself. This data
is used as a prefix in the HMAC calculation for stream and block
ciphers, or as additional authenticated data for AEAD ciphers.
Define a "TLS authentication header" structure to hold this data as a
contiguous block, in order to meet the alignment requirement for AEAD
ciphers such as GCM.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
b6eef14858