Document and test the current behavior, even if it is weird:
* For Weierstrass keys, the error is MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL,
not MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL.
* For Weierstrass keys, a smaller output buffer is ok if the output fits.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
When exporting a key, MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE should not happen.
This error indicates that the curve is not supported, but that would prevent
the creation of the key.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add non-regression tests. Update some test functions to not assume that
byte_length == bit_length / 8.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
In some configurations (e.g. ECDH but no ECDSA or RSA), the PK module is
useful but cannot perform any signatures. Then modern GCC complains:
```
../source/tests/suites/test_suite_pk.function: In function ‘test_pk_sign_verify’:
../source/tests/suites/test_suite_pk.function:1136:12: error: array subscript 0 is outside array bounds of ‘unsigned char[0]’ [-Werror=array-bounds]
../source/tests/suites/test_suite_pk.function:1094:19: note: while referencing sig’
…
```
This fixes test-ref-configs.pl with a modern GCC (specifically with
config-thread.h).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Set unique configuration names in the outcome file. This was lost in the
rewrite from depends-*.pl to depends.py.
Fix#7290
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Upon further consideration we think that a remote attacker close to the
victim might be able to have precise enough timing information to
exploit the side channel as well. Update the Changelog to reflect this.
Signed-off-by: Janos Follath <janos.follath@arm.com>
The signature and naming of the Montgomrey initialisation function in
development and in the LTS was different. Align them for easier
readability and maintenance.
Signed-off-by: Janos Follath <janos.follath@arm.com>
Any timing variance dependant on the output of this function enables a
Bleichenbacher attack. It is extremely difficult to use safely.
In the Marvin attack paper
(https://people.redhat.com/~hkario/marvin/marvin-attack-paper.pdf) the
author suggests that implementations of PKCS 1.5 decryption that don't
include a countermeasure should be considered inherently dangerous.
They suggest that all libraries implement the same countermeasure, as
implementing different countermeasures across libraries enables the
Bleichenbacher attack as well.
This is extremely fragile and therefore we don't implement it. The use
of PKCS 1.5 in Mbed TLS implements the countermeasures recommended in
the TLS standard (7.4.7.1 of RFC 5246) and is not vulnerable.
Add a warning to PKCS 1.5 decryption to warn users about this.
Signed-off-by: Janos Follath <janos.follath@arm.com>
So far we needed it only locally here, but we will need calculating RR
for safe unblinding in RSA as well.
Signed-off-by: Janos Follath <janos.follath@arm.com>
