tls13: Share write ecdh_key_exchange function
Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index 4bee319..f5d791f 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -1535,6 +1535,63 @@
return( 0 );
}
+
+int mbedtls_ssl_tls13_generate_and_write_ecdh_key_exchange(
+ mbedtls_ssl_context *ssl,
+ uint16_t named_group,
+ unsigned char *buf,
+ unsigned char *end,
+ size_t *out_len )
+{
+ psa_status_t status = PSA_ERROR_GENERIC_ERROR;
+ int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+ psa_key_attributes_t key_attributes;
+ size_t own_pubkey_len;
+ mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+ size_t ecdh_bits = 0;
+
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "Perform PSA-based ECDH computation." ) );
+
+ /* 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 );
+
+ ssl->handshake->ecdh_bits = ecdh_bits;
+
+ 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,
+ buf, (size_t)( end - buf ),
+ &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 );
+
+ }
+
+ *out_len = own_pubkey_len;
+
+ return( 0 );
+}
#endif /* MBEDTLS_ECDH_C */
#endif /* MBEDTLS_SSL_TLS_C && MBEDTLS_SSL_PROTO_TLS1_3 */