`mbedtls_ecdsa_sign_det` reuses the internal HMAC-DRBG instance to
implement blinding. The advantage of this is that the algorithm is
deterministic too, not just the resulting signature. The drawback is
that the blinding is always the same for the same key and message.
This diminishes the efficiency of blinding and leaks information about
the private key.
A function that takes external randomness fixes this weakness.
* crypto/development: (863 commits)
crypto_platform: Fix typo
des: Reduce number of self-test iterations
Fix -O0 build for Aarch64 bignum multiplication.
Make GNUC-compatible compilers use the right mbedtls_t_udbl again on Aarch64 builds.
Add optimized bignum multiplication for Aarch64.
Enable 64-bit limbs for all Aarch64 builds.
HMAC DRBG: Split entropy-gathering requests to reduce request sizes
psa: Use application key ID where necessary
psa: Adapt set_key_id() for when owner is included
psa: Add PSA_KEY_ID_INIT
psa: Don't duplicate policy initializer
crypto_extra: Use const seed for entropy injection
getting_started: Update for PSA Crypto API 1.0b3
Editorial fixes.
Cross reference 'key handles' from INVALID_HANDLE
Update documentation for psa_destroy_key
Update documentation for psa_close_key
Update psa_open_key documentation
Remove duplicated information in psa_open_key
Initialize key bits to max size + 1 in psa_import_key
...
* open output distinct key handles
* each handle must be closed
* destroying a key does not invalidate other handles
* closing a key can/might fail an active operation (but not required)
It may be possible that the implementation runs out of
memory when exporting a key from storage or a secure
element. For example, it may not be possible to directly
move the data from storage to the caller, so the implementation
will have to buffer the material temporarily (an issue if dynamic
memory allocation scheme is used). For a large key
this is more likely to return.
It may be possible that an implementation does not
fetch key material until a command like
this is called and such an error may occur if an
off-chip secure storage dependency may have been wiped.
Note that PSA_ERROR_NOT_PERMITTED is not included
because I can't think of a scenario where you have
a valid key handle but aren't allowed to read the
attributes
