While this does require quite a bit of memory, on initiators there are
usually fewer concurrent SAs getting created so this should be less of
an issue than on a gateway that handles lots of SAs as responder.
The speed up is about 30% on the initiator during the decapsulation,
while the key generation does take a bit more time (about 3%).
This follows FIPS 203 relatively closely but takes some ideas from the
reference implementation. In particular, how to avoid potential
side-channels via direct C division/modulo operations. However, it just
uses Barrett reduction (no Montgomery reduction) and no negative
coefficients to avoid number format conversions and keep the
implementation clearer.
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
Both Diffie-Hellman (DH) and Key Encapsulation Mechanism (KEM) based
key exchange methods use a common ke_test_vector format. The
set_seed() function is used to provide deterministic private key
material for the crypto tests.
If uniqueness checks are disabled and multiple IKE_SAs with the same
identities are created, an offline lease could have gotten reassigned
during a make-before-break reauthentication if such an SA was closed
earlier. Checking for an online lease for the same client (IP/port)
first ensures that the correct IP is reassigned during the
reauthentication.
References strongswan/strongswan#2472
