commit c89f3ea9f261136c8e52bda58419b401b5fdcbb3
author Przemek Stekiel <przemyslaw.stekiel@mobica.com> Thu May 18 15:45:53 2023 +0200
committer Przemek Stekiel <przemyslaw.stekiel@mobica.com> Tue Jun 06 12:31:08 2023 +0200
tree 8a02f79eb82f5a3b2ce018a392caea9a6a1b289a
parent cceb933e309786aef3a7bf394597126cff8ee55a

Add support for FFDH in TLS 1.3

Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>

library/ssl_tls13_keys.c

diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 46caa45..c69078d 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -1484,8 +1484,15 @@
      * are derived in the handshake secret derivation stage.
      */
     if (mbedtls_ssl_tls13_key_exchange_mode_with_ephemeral(ssl)) {
-        if (mbedtls_ssl_tls13_named_group_is_ecdhe(handshake->offered_group_id)) {
-#if defined(PSA_WANT_ALG_ECDH)
+        if (mbedtls_ssl_tls13_named_group_is_ecdhe(handshake->offered_group_id) ||
+            mbedtls_ssl_tls13_named_group_is_dhe(handshake->offered_group_id)) {
+#if defined(PSA_WANT_ALG_ECDH) || defined(PSA_WANT_ALG_FFDH)
+            psa_algorithm_t alg = 0;
+            if (mbedtls_ssl_tls13_named_group_is_ecdhe(handshake->offered_group_id)) {
+                alg = PSA_ALG_ECDH;
+            } else {
+                alg = PSA_ALG_FFDH;
+            }
             /* Compute ECDH shared secret. */
             psa_status_t status = PSA_ERROR_GENERIC_ERROR;
             psa_key_attributes_t key_attributes = PSA_KEY_ATTRIBUTES_INIT;
@@ -1504,7 +1511,7 @@
             }
 
             status = psa_raw_key_agreement(
-                PSA_ALG_ECDH, handshake->ecdh_psa_privkey,
+                alg, handshake->ecdh_psa_privkey,
                 handshake->ecdh_psa_peerkey, handshake->ecdh_psa_peerkey_len,
                 shared_secret, shared_secret_len, &shared_secret_len);
             if (status != PSA_SUCCESS) {
@@ -1521,7 +1528,7 @@
             }
 
             handshake->ecdh_psa_privkey = MBEDTLS_SVC_KEY_ID_INIT;
-#endif /* PSA_WANT_ALG_ECDH */
+#endif /* PSA_WANT_ALG_ECDH || PSA_WANT_ALG_FFDH */
         } else {
             MBEDTLS_SSL_DEBUG_MSG(1, ("Group not supported."));
             return MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;