Change ssl_tls13_generate_and_write_ecdh_key_exchange() to use PSA
Generate ECDH private key using psa_generate_key()
Export the public part of the ECDH private key using psa_export_public_key()
Signed-off-by: Przemyslaw Stekiel <przemyslaw.stekiel@mobica.com>
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index ca91d67..b7cb995 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -148,33 +148,67 @@
unsigned char *end,
size_t *out_len )
{
- int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
- const mbedtls_ecp_curve_info *curve_info =
- mbedtls_ecp_curve_info_from_tls_id( named_group );
+ psa_status_t status = PSA_ERROR_GENERIC_ERROR;
+ int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+ psa_key_attributes_t key_attributes;
+ unsigned char own_pubkey[MBEDTLS_PSA_MAX_EC_PUBKEY_LENGTH];
+ size_t own_pubkey_len;
+ mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+ size_t ecdh_bits = 0;
- if( curve_info == NULL )
- return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "Perform PSA-based ECDH computation." ) );
- MBEDTLS_SSL_DEBUG_MSG( 3, ( "offer curve %s", curve_info->name ) );
+ // --- Just for now --- !!!
+ psa_crypto_init();
- if( ( ret = mbedtls_ecdh_setup_no_everest( &ssl->handshake->ecdh_ctx,
- curve_info->grp_id ) ) != 0 )
- {
- MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_setup_no_everest", ret );
- return( ret );
- }
+ /* Convert EC group to PSA key type. */
+ if( ( handshake->ecdh_psa_type =
+ mbedtls_psa_parse_tls_ecc_group( named_group, &ecdh_bits ) ) == 0 )
+ return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
- ret = mbedtls_ecdh_tls13_make_params( &ssl->handshake->ecdh_ctx, out_len,
- buf, end - buf,
- ssl->conf->f_rng, ssl->conf->p_rng );
- if( ret != 0 )
- {
- MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_tls13_make_params", ret );
- return( ret );
- }
+ if( ecdh_bits > 0xffff )
+ return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+ ssl->handshake->ecdh_bits = (uint16_t) ecdh_bits;
- MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
- MBEDTLS_DEBUG_ECDH_Q );
+ key_attributes = psa_key_attributes_init();
+ psa_set_key_usage_flags( &key_attributes, PSA_KEY_USAGE_DERIVE );
+ psa_set_key_algorithm( &key_attributes, PSA_ALG_ECDH );
+ psa_set_key_type( &key_attributes, handshake->ecdh_psa_type );
+ psa_set_key_bits( &key_attributes, handshake->ecdh_bits );
+
+ /* Generate ECDH private key. */
+ status = psa_generate_key( &key_attributes,
+ &handshake->ecdh_psa_privkey );
+ if( status != PSA_SUCCESS )
+ {
+ ret = psa_ssl_status_to_mbedtls( status );
+ MBEDTLS_SSL_DEBUG_RET( 1, "psa_generate_key", ret );
+ return( ret );
+
+ }
+
+ /* Export the public part of the ECDH private key from PSA. */
+ status = psa_export_public_key( handshake->ecdh_psa_privkey,
+ own_pubkey, sizeof( own_pubkey ),
+ &own_pubkey_len );
+ if( status != PSA_SUCCESS )
+ {
+ ret = psa_ssl_status_to_mbedtls( status );
+ MBEDTLS_SSL_DEBUG_RET( 1, "psa_export_public_key", ret );
+ return( ret );
+
+ }
+
+ if( own_pubkey_len > (size_t)( end - buf ) )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "No space in the buffer for ECDH public key." ) );
+ return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
+ }
+
+ *out_len = own_pubkey_len;
+
+ memcpy( buf, &own_pubkey, own_pubkey_len );
+
return( 0 );
}
#endif /* MBEDTLS_ECDH_C */
@@ -283,8 +317,7 @@
*/
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
p += 4;
- ret = ssl_tls13_generate_and_write_ecdh_key_exchange( ssl, group_id,
- p, end,
+ ret = ssl_tls13_generate_and_write_ecdh_key_exchange( ssl, group_id, p, end,
&key_exchange_len );
p += key_exchange_len;
if( ret != 0 )