This registers support for the ML_KEM_{512,768,1024} key exchange
algorithms in the `openssl` plugin when built using AWS-LC as the
libcrypto. To do this, we introduce the `openssl_kem` source files
which implement the key exchange algorithm using the Key Encapsulation
Mechanism (KEM) API. Future KEM algorithms can be implemented
generically using this interface by substituting the appropriate NIDs.
It also supports both seeded (via DRBG) and unseeded modes depending
on the user's requirements for KATs or entropy sources.
It should be noted that this does not add support for KEM algorithms
within upstream OpenSSL and is API incompatible. Future work will need
to condition out the incompatibilities as-appropriate. However, the
high-level logic should be the same for all KEMs and KEM APIs.
References strongswan/strongswan#2228Closesstrongswan/strongswan#2490
The HKDF-Expand() function defined in RFC 5869 is basically the same as
IKEv2's prf+(), so we can use the former to implement the latter.
However, we can only support HMAC-based PRFs this way, which should be
fine as others are rarely used.
While X25519 was already added with 1.1.0a, its use would be a lot more
complicated, as the helpers like EVP_PKEY_new_raw_public_key() were only
added in 1.1.1, which also added X448.
INCLUDES are now deprecated and throw warnings when using automake 1.13.
We now also differentiate AM_CPPFLAGS and AM_CFLAGS, where includes and
defines are passed to AM_CPPFLAGS only.
Gerardo Ravago