For AEAD ciphers, the information contained in mbedtls_cipher_info
is not enough to deduce a PSA algorithm value of type psa_algorithm_t.
This is because mbedtls_cipher_info doesn't contain the AEAD tag
length, while values of type psa_algorithm_t do.
This commit adds the AEAD tag length as a separate parameter
to mbedtls_cipher_setup_psa(). For Non-AEAD ciphers, the value
must be 0.
This approach is preferred over passing psa_algorithm_t directly
in order to keep the changes in existing code using the cipher layer
small.
Mbed TLS cipher layer allows usage of keys for other purposes
than indicated in the `operation` parameter of `mbedtls_cipher_setkey()`.
The semantics of the PSA Crypto API, in contrast, checks key
usage against the key policy.
As a remedy, this commit modifies the PSA key slot setup to
always allow both encryption and decryption.
This commit implements the internal key slot management performed
by PSA-based cipher contexts. Specifically, `mbedtls_cipher_setkey()`
wraps the provided raw key material into a key slot, and
`mbedtls_cipher_free()` destroys that key slot.
This field determines whether a cipher context should
use an external implementation of the PSA Crypto API for
cryptographic operations, or Mbed TLS' own crypto library.
The commit also adds dummy implementations for the cipher API.
In case of AEAD ciphers, the cipher mode (and not even the entire content
of mbedtls_cipher_info_t) doesn't uniquely determine a psa_algorithm_t
because it doesn't specify the AEAD tag length, which however is included
in psa_algorithm_t identifiers.
This commit adds a tag length value to mbedtls_psa_translate_cipher_mode()
to account for that ambiguity.
This commit adds the header file mbedtls/psa_util.h which contains
static utility functions `mbedtls_psa_xxx()` used in the integration
of PSA Crypto into Mbed TLS.
Warning: These functions are internal only and may change at any time.
The test suites `test_suite_gcm.aes{128,192,256}_en.data` contains
numerous NIST test vectors for AES-*-GCM against which the GCM
API mbedtls_gcm_xxx() is tested.
However, one level higher at the cipher API, no tests exist which
exercise mbedtls_cipher_auth_{encrypt/decrypt}() for GCM ciphers,
although test_suite_cipher.function contains the test auth_crypt_tv
which does precisely that and is already used e.g. in
test_suite_cipher.ccm.
This commit replicates the test vectors from
test_suite_gcm.aes{128,192,256}_en.data in test_suite_cipher.gcm.data
and adds a run of auth_crypt_tv for each of them.
The conversion was mainly done through the sed command line
```
s/gcm_decrypt_and_verify:\([^:]*\):\([^:]*\):\([^:]*\):\([^:]*\):
\([^:]*\):\([^:]*\):\([^:]*\):\([^:]*\):\([^:]*\):\([^:]*\)/auth_crypt_tv:
\1:\2:\4:\5:\3:\7:\8:\9/
```
