After mitigating the 'triple handshake attack' by checking that
the peer's end-CRT didn't change during renegotation, the current
code avoids re-parsing the CRT by moving the CRT-pointer from the
old session to the new one. While efficient, this will no longer
work once only the hash of the peer's CRT is stored beyond the
handshake.
This commit removes the code-path moving the old CRT, and instead
frees the entire peer CRT chain from the initial handshake as soon
as the 'triple handshake attack' protection has completed.
Commit "Smoke-test operation contexts after setup+abort" replaced
{failed-setup; abort} sequences by {failed-setup; successful-setup}.
We want to test that, but we also want to test {failed-setup; abort}.
So test {failed-setup; abort; failed-setup; successful-setup}.
After a successful setup followed by abort, or after a failed setup
from an inactive state, a context must be usable. Test this for
hash, MAC and cipher contexts.
Renamed the tests because they are explicitly testing Curve25519 and
nothing else. Improved test coverage, test documentation and extended
in-code documentation with a specific reference to the standard as well.
crypto_extra.h has a dependency on platform_util.h for
MBEDTLS_DEPRECATED_NUMERIC_CONSTANT. Make the dependency explicit by
including platform_util.h. Although in most use cases the header should
already be included by something else, it doesn't hurt to include it
again and helps to clarify dependencies.
The library is able to perform computations and cryptographic schemes on
curves with x coordinate ladder representation. Here we add the
capability to export such points.
The function `mbedtls_mpi_write_binary()` writes big endian byte order,
but we need to be able to write little endian in some caseses. (For
example when handling keys corresponding to Montgomery curves.)
Used `echo xx | tac -rs ..` to transform the test data to little endian.
The private keys used in ECDH differ in the case of Weierstrass and
Montgomery curves. They have different constraints, the former is based
on big endian, the latter little endian byte order. The fundamental
approach is different too:
- Weierstrass keys have to be in the right interval, otherwise they are
rejected.
- Any byte array of the right size is a valid Montgomery key and it
needs to be masked before interpreting it as a number.
Historically it was sufficient to use mbedtls_mpi_read_binary() to read
private keys, but as a preparation to improve support for Montgomery
curves we add mbedtls_ecp_read_key() to enable uniform treatment of EC
keys.
For the masking the `mbedtls_mpi_set_bit()` function is used. This is
suboptimal but seems to provide the best trade-off at this time.
Alternatives considered:
- Making a copy of the input buffer (less efficient)
- removing the `const` constraint from the input buffer (breaks the api
and makes it less user friendly)
- applying the mask directly to the limbs (violates the api between the
modules and creates and unwanted dependency)
The library is able to perform computations and cryptographic schemes on
curves with x coordinate ladder representation. Here we add the
capability to import such points.
The function `mbedtls_mpi_read_binary()` expects big endian byte order,
but we need to be able to read from little endian in some caseses. (For
example when handling keys corresponding to Montgomery curves.)
Used `echo xx | tac -rs .. | tr [a-z] [A-Z]` to transform the test data
to little endian and `echo "ibase=16;xx" | bc` to convert to decimal.
Define MBEDTLS_ECDH_LEGACY_CONTEXT in config.h instead of hard-coding
this in ecdh.h so that its absence can be tested. Document it as
experimental so that we reserve the right to change it in the future.
Additional work done as part of merge:
- Run ./tests/scripts/check-generated-files.sh and check in the
resulting changes to programs/ssl/query_config.c
If mbedtls_ecdh_get_params is called with keys belonging to
different groups, make it return an error the second time, rather than
silently interpret the first key as being on the second curve.
This makes the non-regression test added by the previous commit pass.
Add a test case for doing an ECDH calculation by calling
mbedtls_ecdh_get_params on both keys, with keys belonging to
different groups. This should fail, but currently passes.
In places where we detect a context is in a bad state and there is no
sensitive data to clear, simply return PSA_ERROR_BAD_STATE and don't
abort on behalf of the application. The application will choose what to
do when it gets a bad state error.
The motivation for this change is that an application should decide what
to do when it misuses the API and encounters a PSA_ERROR_BAD_STATE
error. The library should not attempt to abort on behalf of the
application, as that may not be the correct thing to do in all
circumstances.
Calling psa_*_setup() twice on a MAC, cipher, or hash context should
result in a PSA_ERROR_BAD_STATE error because the operation has already
been set up.
Fixes#10
Extend hash bad order test in line with the new bad order tests for MAC
and cipher, covering more cases and making comments and test layout
consistent.
Ensure that when doing hash operations out of order, PSA_ERROR_BAD_STATE
is returned as documented in crypto.h and the PSA Crypto specification.
