ssl_prepare_server_key_exchange(): generate a private/public key and write out the curve identifier and public key using PSA
Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index e9febfd..50715b5 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -3107,6 +3107,89 @@
return( ret );
}
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ psa_status_t status = PSA_ERROR_GENERIC_ERROR;
+ psa_key_attributes_t key_attributes;
+ mbedtls_ssl_handshake_params *handshake = ssl->handshake;
+ size_t ecdh_bits = 0;
+ uint8_t *p = ssl->out_msg + ssl->out_msglen;
+ const size_t header_size = 4; // curve_type, namedcurve, data length
+ const size_t data_length_size = 1;
+
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "Perform PSA-based ECDH computation." ) );
+
+ /* Convert EC group to PSA key type. */
+ if( ( handshake->ecdh_psa_type =
+ PSA_KEY_TYPE_ECC_KEY_PAIR( mbedtls_ecc_group_to_psa(
+ (*curve)->grp_id, &ecdh_bits ) ) ) == 0 )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "Could not convert ECC group to PSA." ) );
+ return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+ }
+
+ if( ecdh_bits > 0xffff )
+ {
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "Invalid ecdh_bits." ) );
+ return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+ }
+ handshake->ecdh_bits = (uint16_t) 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 );
+
+ /*
+ * ECParameters curve_params
+ *
+ * First byte is curve_type, always named_curve
+ */
+ *p++ = MBEDTLS_ECP_TLS_NAMED_CURVE;
+
+ /*
+ * Next two bytes are the namedcurve value
+ */
+ MBEDTLS_PUT_UINT16_BE( (*curve)->tls_id, p, 0 );
+ p += 2;
+
+ /* 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 );
+ }
+
+ /*
+ * ECPoint public
+ *
+ * First byte is data length.
+ * It will be filled later. p holds now the data length location.
+ */
+
+ /* Export the public part of the ECDH private key from PSA.
+ * Make one byte space for the length.
+ */
+ status = psa_export_public_key( handshake->ecdh_psa_privkey,
+ p + data_length_size,
+ (size_t)( MBEDTLS_SSL_OUT_CONTENT_LEN - ssl->out_msglen - header_size ),
+ &len );
+ if( status != PSA_SUCCESS )
+ {
+ ret = psa_ssl_status_to_mbedtls( status );
+ MBEDTLS_SSL_DEBUG_RET( 1, "psa_export_public_key", ret );
+ return( ret );
+ }
+
+ /* Store the length of the exported public key. */
+ *p = (uint8_t) len;
+
+ /* Determine full message length. */
+ len += header_size;
+#else
if( ( ret = mbedtls_ecdh_make_params(
&ssl->handshake->ecdh_ctx, &len,
ssl->out_msg + ssl->out_msglen,
@@ -3116,6 +3199,7 @@
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_make_params", ret );
return( ret );
}
+#endif
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_SERVER_SIGNATURE_ENABLED)
dig_signed = ssl->out_msg + ssl->out_msglen;