Change the key derivation API to take inputs in multiple steps,
instead of a single one-site-fits-poorly function.
Conflicts:
* include/psa/crypto.h: merge independent changes in the documentation
of psa_key_agreement (public_key from the work on public key formats
vs general description and other parameters in the work on key derivation).
* tests/suites/test_suite_psa_crypto.data: update the key agreement
tests from the work on key derivation to the format from the work on
public key formats.
* tests/suites/test_suite_psa_crypto_metadata.function: reconcile the
addition of unrelated ALG_IS_xxx macros
Get rid of "key selection" algorithms (of which there was only one:
raw key selection).
Encode key agreement by combining a raw key agreement with a KDF,
rather than passing the KDF as an argument of a key agreement macro.
You can use PSA_ALG_ANY_HASH to build the algorithm value for a
hash-and-sign algorithm in a policy. Then the policy allows usage with
this hash-and-sign family with any hash.
Test that PSA_ALG_ANY_HASH-based policies allow a specific hash, but
not a different hash-and-sign family. Test that PSA_ALG_ANY_HASH is
not valid for operations, only in policies.
Test for a subclass of public-key algorithm: those that perform
full-domain hashing, i.e. algorithms that can be broken down as
sign(key, hash(message)).
A key selection algorithm is similar to a key derivation algorithm in
that it takes a secret input and produces a secret output stream.
However, unlike key derivation algorithms, there is no expectation
that the input cannot be reconstructed from the output. Key selection
algorithms are exclusively meant to be used on the output of a key
agreement algorithm to select chunks of the shared secret.
If some algorithms are excluded in the build, it's ok for the corresponding
macros not to give the correct results. Therefore the corresponding test cases
should depend on the implementation of the algorithm. For example, it's ok for
PSA_HASH_MAX_SIZE to be less than PSA_HASH_SIZE(PSA_ALG_SHA_512) if we build
without SHA-512 support, and we indeed do this. It's even ok for an
implementation to return 0 for PSA_ALG_IS_HASH(PSA_ALG_SHA_512) if it doesn't
support SHA-512; we return 1 anyway but the tests are less
implementation-specific if we don't enforce it.
This commit adds dependencies on symbols that don't exist in Mbed TLS,
for algorithms that Mbed TLS doesn't implement. These are:
MBEDTLS_SHA512_256 for SHA-512/256, MBEDTLS_SHA3_C for SHA-3,
MBEDTLS_DSA_C and MBEDTLS_DSA_DETERMINISTIC for DSA, and
MBEDTLS_ECP_DP_xxx_ENABLED for elliptic curves that have a PSA
encoding but are not supported in Mbed TLS.
For all key types, validate feature test macros (PSA_KEY_TYPE_IS_xxx).
For asymmetric keys (public key or key pair), validate the
corresponding public/pair type.
For ECC keys, validate GET_CURVE.
For all algorithms, validate feature test macros (PSA_ALG_IS_xxx).
For hash algorithms, validate the exact hash size, and validate
xxx_GET_HASH macros on dependent algorithms.
For MAC algorithms, validate the MAC size. For AEAD algorithms,
validate the tag size.
There is a separate test case for each HMAC algorithm, which is
necessary because each has its own MAC size. For other hash-dependent
algorithms, there is no interesting variation to test here, so only
one hash gets tested.
