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Add key agreement for FFDH keys

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Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>
This commit is contained in:
Przemek Stekiel 2022-12-01 14:59:15 +01:00
parent 472b3f33b9
commit fb3dd54b24
1 changed files with 74 additions and 0 deletions
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74
library/psa_crypto.c
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@ -1490,6 +1490,59 @@ cleanup:
return PSA_SUCCESS; return PSA_SUCCESS;
} }
#if defined(MBEDTLS_PSA_BUILTIN_ALG_FFDH)
static psa_status_t psa_key_agreement_ffdh(const uint8_t *peer_key,
size_t peer_key_length,
const uint8_t *our_key,
size_t our_key_length,
uint8_t *shared_secret,
size_t shared_secret_size,
size_t *shared_secret_length)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi P, G, X, GY, K;
const size_t calculated_shared_secret_size = peer_key_length;
if (peer_key_length != our_key_length ||
calculated_shared_secret_size > shared_secret_size) {
return PSA_ERROR_INVALID_ARGUMENT;
}
mbedtls_mpi_init(&P); mbedtls_mpi_init(&G);
mbedtls_mpi_init(&X); mbedtls_mpi_init(&GY);
mbedtls_mpi_init(&K);
status = psa_ffdh_set_prime_generator(peer_key_length, &P, &G);
if (status == PSA_SUCCESS) {
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&X, our_key,
our_key_length));
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&GY, peer_key,
peer_key_length));
/* Calculate shared secret public key: K = G^(XY) mod P */
MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&K, &GY, &X, &P, NULL));
MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&K, shared_secret,
calculated_shared_secret_size));
*shared_secret_length = calculated_shared_secret_size;
}
cleanup:
mbedtls_mpi_free(&P); mbedtls_mpi_free(&G);
mbedtls_mpi_free(&X); mbedtls_mpi_free(&GY);
mbedtls_mpi_free(&K);
if (status == PSA_SUCCESS && ret != 0) {
return mbedtls_to_psa_error(ret);
}
return PSA_SUCCESS;
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_FFDH */
static psa_status_t psa_export_ffdh_public_key_internal( static psa_status_t psa_export_ffdh_public_key_internal(
const uint8_t *key_buffer, const uint8_t *key_buffer,
size_t key_buffer_size, size_t key_buffer_size,
@ -6118,6 +6171,11 @@ static psa_status_t psa_key_agreement_try_support(psa_algorithm_t alg)
if (alg == PSA_ALG_ECDH) { if (alg == PSA_ALG_ECDH) {
return PSA_SUCCESS; return PSA_SUCCESS;
} }
#endif
#if defined(PSA_WANT_ALG_FFDH)
if (alg == PSA_ALG_FFDH) {
return PSA_SUCCESS;
}
#endif #endif
(void) alg; (void) alg;
return PSA_ERROR_NOT_SUPPORTED; return PSA_ERROR_NOT_SUPPORTED;
@ -6707,6 +6765,22 @@ psa_status_t psa_key_agreement_raw_builtin(const psa_key_attributes_t *attribute
shared_secret_size, shared_secret_size,
shared_secret_length); shared_secret_length);
#endif /* MBEDTLS_PSA_BUILTIN_ALG_ECDH */ #endif /* MBEDTLS_PSA_BUILTIN_ALG_ECDH */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_FFDH)
case PSA_ALG_FFDH:
if (!PSA_KEY_TYPE_IS_DH_KEY_PAIR(psa_get_key_type(attributes))) {
return PSA_ERROR_INVALID_ARGUMENT;
}
return psa_key_agreement_ffdh(peer_key,
peer_key_length,
key_buffer,
key_buffer_size,
shared_secret,
shared_secret_size,
shared_secret_length);
#endif /* MBEDTLS_PSA_BUILTIN_ALG_FFDH */
default: default:
(void) attributes; (void) attributes;
(void) key_buffer; (void) key_buffer;