This patch introduces the following changes:
* Documentation for `mbedtls_ecp_modulus_setup()`
moved to `ecp_invasive.h`.
* Added invalid modulus selector `MBEDTLS_ECP_MOD_NONE`.
* Adjusted negative tests to use invalid selectors.
* Reworded documentation.
Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
Rename the function to 'fix_quasi_reduction' to better suite its functionality.
Also changed the name prefix to suite for the new module.
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
Spec values are now always used for test data, and conversion to
internal representation is done in the test function.
Signed-off-by: Werner Lewis <werner.lewis@arm.com>
Test cases added to check curve parameters and information for each
curve supported. Expected parameters are taken from references: SEC 2
for NIST, RFC 5639 for Brainpool, and RFC 7748 for curve25519/curve448.
Signed-off-by: Werner Lewis <werner.lewis@arm.com>
Tests function with various ECP point conditions, covering freshly
initialized, zeroed, non-zero, and freed points.
Signed-off-by: Werner Lewis <werner.lewis@arm.com>
- parameter name in function description
- test_suite_ecp.data: add new line at the end of file
Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>
* Add tests to validate MSB not ok for Curve25519 and
Curve448.
* Add a test to generate key for for Curve448.
Signed-off-by: Archana <archana.madhavan@silabs.com>
mbedtls_ecp_read_key and mbedtls_ecp_write_key are updated to include
support for Curve448 as prescribed by RFC 7748 §5.
Test suites have been updated to validate curve448 under Montgomery
curves.
Signed-off-by: Archana <archana.madhavan@silabs.com>
Negative x coordinate was tested with the value -1. It happens to be one
of the low order points both for Curve25519 and Curve448 and might be
rejected because of that and not because it is negative. Make sure that
x < 0 is the only plausible reason for the point to be rejected.
Signed-off-by: Janos Follath <janos.follath@arm.com>
A test case for which the loop would take practically forever if it was
reached. The point would be to validate that the loop is not reached.
The test case should cause the CI to time out if starting with the
current code, ecp_check_pubkey_mx() was changed to call
ecp_check_pubkey_x25519() first and run the mbedtls_mpi_size(() test
afterwards, which would make no semantic difference in terms of memory
contents when the function returns, but would open the way for a DoS.
Signed-off-by: Janos Follath <janos.follath@arm.com>
We were already rejecting them at the end, due to the fact that with the
usual (x, z) formulas they lead to the result (0, 0) so when we want to
normalize at the end, trying to compute the modular inverse of z will
give an error.
If we wanted to support those points, we'd a special case in
ecp_normalize_mxz(). But it's actually permitted by all sources
(RFC 7748 say we MAY reject 0 as a result) and recommended by some to
reject those points (either to ensure contributory behaviour, or to
protect against timing attack when the underlying field arithmetic is
not constant-time).
Since our field arithmetic is indeed not constant-time, let's reject
those points before they get mixed with sensitive data (in
ecp_mul_mxz()), in order to avoid exploitable leaks caused by the
special cases they would trigger. (See the "May the Fourth" paper
https://eprint.iacr.org/2017/806.pdf)
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
Since mbedtls_mpi_random() is not specific to ECC code, move it from
the ECP module to the bignum module.
This increases the code size in builds without short Weierstrass
curves (including builds without ECC at all) that do not optimize out
unused functions.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Rename mbedtls_ecp_gen_privkey_sw to mbedtls_mpi_random since it has
no particular connection to elliptic curves beyond the fact that its
operation is defined by the deterministic ECDSA specification. This is
a generic function that generates a random MPI between 1 inclusive and
N exclusive.
Slightly generalize the function to accept a different lower bound,
which adds a negligible amount of complexity.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add unit tests for private key generation on short Weierstrass curves.
These tests validate that the result is within the desired range.
Additionally, they validate that after performing many iterations, the
range is covered to an acceptable extent: for tiny ranges, all values
must be reached; for larger ranges, all value bits must reach both 0
and 1.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Don't calculate the bit-size of the initially generated random number.
This is not necessary to reach the desired distribution of private
keys, and creates a (tiny) side channel opportunity.
This changes the way the result is derived from the random number, but
does not affect the resulting distribution.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The library rejected an RNG input of all-bits-zero, which led to the
key 2^{254} (for Curve25519) having a 31/32 chance of being generated
compared to other keys. This had no practical impact because the
probability of non-compliance was 2^{-256}, but needlessly
complicated the code.
The exception was added in 98e28a74e3 to
avoid the case where b - 1 wraps because b is 0. Instead, change the
comparison code to avoid calculating b - 1.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Test the exact output from known RNG input. This is overly
constraining, but ensures that the code has good properties.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
