Also enables the `kdf` plugin automatically if building against an older
version of OpenSSL.
Closesstrongswan/strongswan#2602
Co-authored-by: Tobias Brunner <[email protected]>
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
AWS-LC lacks support for a number of elliptic curve algorithms so this
adds some conditional macros to avoid registering the related plugin
features. Support for curves ed448 and x448 is completely absent and are
not planned for implementation as they are no longer recommended for use.
While ed25519 is supported by the library, a single missing API for
ASN.1 DER encoding of its private keys is missing which prevents its
use in strongSwan. Future work may remove this limitation, but for now
we will disable the functionality.
Closesstrongswan/strongswan#2109
This was the order before 46a6b06282 ("openssl: Only announce ECDH
groups actually supported by OpenSSL") but that's not really the reason
for this change. It's related to the Android app, where we previously
didn't support these DH groups in BoringSSL and added the curve25519
plugin after the openssl plugin instead. This resulted in the same
order, i.e. ECDH groups before curve25519. With the switch to OpenSSL
and the mentioned commit, this changed and curve25519 was now the first
group that was proposed and used for the KE payload. Not really an
issue you'd think, however, there are apparently Zyxel Firewalls with
older firmware versions (some forum posts mentioned a fix in V5.31) that
can't handle KE payloads with DH groups > 21 (ecp521). So with
curve25519 (31) proposed in the KE payload, they silently dropped the
IKE_SA_INIT request and no connection could be established.
This avoids the use of a variable length array, which should probably
be avoided in general due to potential performance, portability and
security issues (not in this particular case, though).
Closesstrongswan/strongswan#1095
More of this code was already removed with previous commits.
While versions < 1.1.1 are not officially supported anymore, 1.0.2 might
still be in use because before 3.x that was the latest version with
official FIPS support (OpenSSL apparently also provides extended commercial
support for it).
The old API has been deprecated with OpenSSL 3 and direct access to the
state isn't possible via EVP API. In the future we might just remove this
implementation but we'd probably have to implement EAP-AKA' first, which
uses HMAC-SHA-256 with IKEv2's prf+ construct to derive keys instead
of this weird construct (plus what fips-prf builds around it) that's used
by EAP-AKA.
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.
There is a conflict between atexit() handlers registered by OpenSSL and
some executables (e.g. swanctl or pki) to deinitialize libstrongswan.
Because plugins are usually loaded after atexit() has been called, the
handler registered by OpenSSL will run before our handler. So when the
latter destroys the plugins it's a bad idea to try to access any OpenSSL
objects as they might already be invalid.
Fixes: f556fce16b ("openssl: Load "legacy" provider in OpenSSL 3 for algorithms like MD4, DES etc.")
Closesstrongswan/strongswan#921
We still require these algorithms for e.g. EAP-MSCHAPv2, so the option is
enabled, by default. To use other providers (e.g. fips or even custom
ones), the option can be disabled and the providers to load/activate can
be configured in openssl.cnf. For instance, the following has the same
effect as enabling the option:
openssl_conf = openssl_init
[openssl_init]
providers = providers
[providers]
default = activate
legacy = activate
[activate]
activate = yes
Determined by whether the library provides curves for it or not.
For instance, in the OpenSSL 3 FIPS provider the Brainpool curves are
not included. And in the Fedora package several weak curves are
explicitly patched out and the Brainpool curves are omitted even in
non-FIPS mode.
Using the workaround with the EVP interface, which we use to derive shared
keys since 74e02ff5e6 ("openssl: Mainly use EVP interface for ECDH"),
would actually require us to register the OIDs of these curves as NID.
Otherwise, the two EC_GROUPs used by private and public key objects
are not considered the same and the key derivation fails.
Since the curves are supported by OpenSSL since 1.0.2 it's probably rare to
find a version without them nowadays. One exception is the old BoringSSL
version we still use on Android, which defines the NIDs but not the curve
data. However, that version also lacks support to register OIDs as NIDs,
so the only option to support these groups there would be to got back to not
using the EVP interface, which isn't in anyone's interest. If there really
is a need for them there, we could probably patch BoringSSL or use OpenSSL.
While CCM is available in earlier versions, we only use it with
OpenSSL 1.1.0 and newer because the generic control variables are not
available before and we default to GCM for them.
Closesstrongswan/strongswan#353.
According to the documentation, it's generally not necessary to manually
seed OpenSSL's DRBG (and it actually can cause the daemon to lock up
during start up on systems with low entropy if OpenSSL is already trying
to seed it itself and holds the lock). While that might already have been
the case with earlier versions, it's not explicitly stated in their
documentation. So we keep the code for these versions.
The functional reference created by ENGINE_init() was never released,
only the structural one created by ENGINE_by_id(). The functional
reference includes an implicit structural reference, which is also
released by ENGINE_finish().
Closesstrongswan/strongswan#119.
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.
Tobias Brunner