Fill the unused part of the output buffer with '!', for consistency
with hash and mac.
On error, set the output length to the output buffer size and fill the
output buffer with '!', again for consistency with hash and mac. This
way an invalid output is more visible in a memory dump.
Restructure the error paths so that there is a single place where the
unused part of the output buffer is filled.
Also remove a redundant initialization of *signature_length to 0.
In tests that had a hard-coded buffer size, use PSA_MAC_MAX_SIZE or
PSA_ASYMMETRIC_SIGNATURE_MAX_SIZE as appropriate.
Test that PSA_xxx_MAX_SIZE is larger than the size used in tests that
expect a specific output.
To avoid a possible loss of precision, and to be semantically correct,
use psa_key_slot_t (which is 16 bits) instead of size_t (which is 32 or
64 bits on common platforms) in mbedtls_psa_crypto_free().
When the size of a buffer is 0, the corresponding pointer argument may
be null. In such cases, library functions must not perform arithmetic
on the pointer or call standard library functions such as memset and
memcpy, since that would be undefined behavior in C. Protect such
cases.
Refactor the storage of a 0-sized raw data object to make it store a
null pointer, rather than depending on the behavior of calloc(1,0).
Previously, the psa_set_key_lifetime() implementation did not match the
function declaration in psa/crypto.h. Value types don't need const,
since they are passed by value. Fix psa_set_key_lifetime()
implementation by making it match its declaration in the header.
This requires defining a maximum RSA key size, since the RSA key size
is the signature size. Enforce the maximum RSA key size when importing
or generating a key.
Change the representation of an ECDSA signature from the ASN.1 DER
encoding used in TLS and X.509, to the concatenation of r and s
in big-endian order with a fixed size. A fixed size helps memory and
buffer management and this representation is generally easier to use
for anything that doesn't require the ASN.1 representation. This is
the same representation as PKCS#11 (Cryptoki) except that PKCS#11
allows r and s to be truncated (both to the same length), which
complicates the implementation and negates the advantage of a
fixed-size representation.
Macros such as PSA_HASH_SIZE whose definitions can be the same
everywhere except in implementations that support non-standard
algorithms remain in crypto.h, at least for the time being.
This header will contain macros that calculate buffer sizes, whose
semantics are standardized but whose definitions are
implementation-specific because they depend on the available algorithms
and on some permitted buffer size tolerances.
Move size macros from crypto_struct.h to crypto_sizes.h, because these
definitions need to be available both in the frontend and in the
backend, whereas structures have different contents.
* Distinguish randomized ECDSA from deterministic ECDSA.
* Deterministic ECDSA needs to be parametrized by a hash.
* Randomized ECDSA only uses the hash for the initial hash step,
but add ECDSA(hash) algorithms anyway so that all the signature
algorithms encode the initial hashing step.
* Add brief documentation for the ECDSA signature mechanisms.
* Also define DSA signature mechanisms while I'm at it. There were
already key types for DSA.
* PSS needs to be parametrized by a hash.
* Don't use `_MGF1` in the names of macros for OAEP and PSS. No one
ever uses anything else.
* Add brief documentation for the RSA signature mechanisms.
Add a negative test for import where the expected key is an EC key
with the correct key size, but the wrong curve. Change the test that
tries to import an RSA key when an EC key is expected to have the
expected key size.
Doxygen interprets `\param` as starting documentation for a new param, or
to extend a previously started `\param` documentation when the same
reference is used. The intention here was to reference the function
parameter, not extend the previous documentation. Use `\p` to refer to
function parameters.
Because exporting-public a symmetric key fails, we have no reasonable
expectation that the exported key length has any value at all other than
something obviously incorrect or "empty", like a key with a length of 0.
Our current implementation explicitly sets the exported key length to 0
on errors, so test for this. Fix the "PSA import/export-public: cannot
export-public a symmetric key" test to expect a key length of 0 instead
of 162.
Make psa_export_key() always set a valid data_length when exporting,
even when there are errors. This makes the API easier to use for buggy
programs (like our test code).
Our test code previously used exported_length uninitialized when
checking to see that the buffer returned was all zero in import_export()
in the case where an error was returned from psa_export_key().
Initialize exported_length to an invalid length, and check that it gets
set properly by psa_export_key(), to avoid this using export_length
uninitialized. Note that the mem_is_zero() check is still valid when
psa_export_key() returns an error, e.g. where exported_length is 0, as
we want to check that nothing was written to the buffer on error.
Out test code also previous passed NULL for the data_length parameter of
psa_export_key() when it expected a failure (in key_policy_fail()).
However, data_length is not allowed to be NULL, especially now that we
write to data_length from psa_export_key() even when there are errors.
Update the test code to not pass in a NULL data_length.
