Unfortunately reusing the new function from the signed constant time
comparison is not trivial.
One option would be to do temporary conditional swaps which would prevent
qualifying input to const. Another way would be to add an additional
flag for the sign and make it an integral part of the computation, which
would defeat the purpose of having an unsigned core comparison.
Going with two separate function for now and the signed version can be
retired/compiled out with the legacy API eventually.
The new function in theory could be placed into either
`library/constant_time.c` or `library/bignum_new.c`. Going with the
first as the other functions in the second are not constant time yet and
this distinction seems more valuable for new (as opposed to belonging to
the `_core` functions.
Signed-off-by: Janos Follath <janos.follath@arm.com>
- We don't check for NULL pointers this deep in the library
- Accessing a NULL pointer when the limb number is 0 as a mistake is the
very similar to any other out of bounds access
- We could potentially mandate at least 1 limb representation for 0 but
we either would need to enforce it or the implementation would be less
robust.
- Allowing zero limb representation - (NULL, 0) in particular - for zero
is present in the legacy interface, if we disallow it, the
compatibility code will need to deal with this (more code size and
opportunities for mistakes)
In summary, interpreting (NULL, 0) as the number zero in the core
interface is the least of the two evils.
Signed-off-by: Janos Follath <janos.follath@arm.com>
The test case where there were extra limbs in the MPI failed and this
commit contains the corresponding fix as well. (We used to use the
minimum required limbs instead of the actual limbs present.)
Signed-off-by: Janos Follath <janos.follath@arm.com>
Test data which is compared as a hex string now uses upper case to
match output of mbedtls_mpi_write_string() output. This removes usage
of strcasecmp().
Signed-off-by: Werner Lewis <werner.lewis@arm.com>
Cases where radix was explictly declared are removed in most cases,
replaced using script. bignum arguments are represented as hexadecimal
strings. This reduces clutter in test data and makes bit patterns
clearer.
Signed-off-by: Werner Lewis <werner.lewis@arm.com>
When USE_PSA is disabled and ECDSA_DETERMINISTIC is enabled, generating
ECDSA signatures via PK requires use of the hash via the MD layer (in
HMAC-DRBG, used by deterministic ECDSA).
When USE_PSA is enabled, ECDSA signatures via PK go through PSA which
always uses non-deterministic ECDSA, so does not rely on HMAC-DRBG/MD.
The condition used here is slightly too strong, but expressing exactly
the optimal condition seems more effort than it's worth for just 3 test
cases.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
Allow PSK exchange mode on GnuTLS server for
NewSessionTicket message test as otherwise
the GnuTLS server does not send tickets.
Signed-off-by: Ronald Cron <ronald.cron@arm.com>
Using VIA_MD_OR_PSA_BASED_ON_USE_PSA was justified by the fact that
until a few commits ago, the test functions here computed hashes using
either MD or PSA, depending on whether USE_PSA was defined (which itself
was justified by the loose reasoning that "PK is USE_PSA territory").
A few commits ago, test code stopped computing hashes because the hash
values became part of the test data. PK itself does not compute hashes.
As a result, VIA_MD_OR_PSA_BASED_ON_USE_PSA is no longer justified.
There are now two kinds of tests:
- those that only rely on hash data (ECDSA, RSA PKCS#1 v1.5) should
depend on VIA_LOWLEVEL_OR_PSA as that is the minimal dependency, hence
the one used for data
- those that were the layer below PK will internally compute a hash (RSA
PKCS#1 v2.1): currently this hash is always computed using MD (on which
MBEDTLS_PKCS1_V21 depends), so legacy dependencies like MBEDTLS_SHA256_C
should be used for now. The previous dependency was morally wrong, it
didn't show in the driver-only tests only because PKCS#1 v2.1 is
disabled in this test for now.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
Fix usage with sed:
s/MBEDTLS_OR_PSA_WANT_\([A-Z_0-9]*\)/MBEDTLS_HAS_\1_VIA_LOWLEVEL_OR_PSA/
s/MBEDTLS_USE_PSA_WANT_\([A-Z_0-9]*\)/MBEDTLS_HAS_\1_VIA_MD_OR_PSA_BASED_ON_USE_PSA/
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
