Curve25519 Compat with LibSSH

1. Add [email protected] back to the list of key exchange
   algorithms.
2. Treat [email protected] as an alias for curve25519-sha256.
3. Remove the reference to ID_ECDH_SHA2_ED25519 from the list of algo
   IDs. It isn't actually a thing.

Author: ejohnstown

src/internal.c

@@ -684,6 +684,7 @@ static const char cannedKexAlgoNames[] =
 #endif
 #ifndef WOLFSSH_NO_CURVE25519_SHA256
     "curve25519-sha256,"
+    "[email protected],"
 #endif
 #if !defined(WOLFSSH_NO_ECDH_SHA2_NISTP521)
     "ecdh-sha2-nistp521,"
@@ -2492,6 +2493,7 @@ static const NameIdPair NameIdMap[] = {
 #ifndef WOLFSSH_NO_CURVE25519_SHA256
     /* See RFC 8731 */
     { ID_CURVE25519_SHA256, TYPE_KEX, "curve25519-sha256" },
+    { ID_CURVE25519_SHA256_LIBSSH, TYPE_KEX, "[email protected]" },
 #endif
     { ID_EXTINFO_S, TYPE_OTHER, "ext-info-s" },
     { ID_EXTINFO_C, TYPE_OTHER, "ext-info-c" },
@@ -3750,6 +3752,7 @@ enum wc_HashType HashForId(byte id)
 #endif
 #ifndef WOLFSSH_NO_CURVE25519_SHA256
         case ID_CURVE25519_SHA256:
+        case ID_CURVE25519_SHA256_LIBSSH:
             return WC_HASH_TYPE_SHA256;
 #endif
 #ifndef WOLFSSH_NO_RSA_SHA2_256
@@ -3827,6 +3830,7 @@ int wcPrimeForId(byte id)
 #endif
 #ifndef WOLFSSH_NO_CURVE25519_SHA256
         case ID_CURVE25519_SHA256:
+        case ID_CURVE25519_SHA256_LIBSSH:
             return ECC_X25519;
 #endif
 #ifndef WOLFSSH_NO_ECDH_SHA2_NISTP521
@@ -11953,6 +11957,7 @@ int SendKexDhReply(WOLFSSH* ssh)
 #endif
 #ifndef WOLFSSH_NO_CURVE25519_SHA256
             case ID_CURVE25519_SHA256:
+            case ID_CURVE25519_SHA256_LIBSSH:
                 useCurve25519 = 1;
                 msgId = MSGID_KEXDH_REPLY;
                 break;
@@ -12535,6 +12540,7 @@ int SendKexDhInit(WOLFSSH* ssh)
 #endif
 #ifndef WOLFSSH_NO_CURVE25519_SHA256
         case ID_CURVE25519_SHA256:
+        case ID_CURVE25519_SHA256_LIBSSH:
             ssh->handshake->useCurve25519 = 1;
             msgId = MSGID_KEXECDH_INIT;
             break;

src/ssh.c

@@ -3027,10 +3027,9 @@ size_t wolfSSH_GetText(WOLFSSH *ssh, WS_Text id, char *str, size_t strSz)
                 case ID_ECDH_SHA2_NISTP256:
                 case ID_ECDH_SHA2_NISTP384:
                 case ID_ECDH_SHA2_NISTP521:
-                case ID_ECDH_SHA2_ED25519:
-                case ID_ECDH_SHA2_ED25519_LIBSSH:
             #ifndef WOLFSSH_NO_CURVE25519_SHA256
                 case ID_CURVE25519_SHA256:
+                case ID_CURVE25519_SHA256_LIBSSH:
             #endif
                     ret = WSNPRINTF(str, strSz, "%s", "ECDH");
                     break;

wolfssh/internal.h

@@ -335,13 +335,12 @@ enum {
     ID_ECDH_SHA2_NISTP256,
     ID_ECDH_SHA2_NISTP384,
     ID_ECDH_SHA2_NISTP521,
-    ID_ECDH_SHA2_ED25519,
-    ID_ECDH_SHA2_ED25519_LIBSSH,
 #ifndef WOLFSSH_NO_ECDH_NISTP256_KYBER_LEVEL1_SHA256
     ID_ECDH_NISTP256_KYBER_LEVEL1_SHA256,
 #endif
 #ifndef WOLFSSH_NO_CURVE25519_SHA256
     ID_CURVE25519_SHA256,
+    ID_CURVE25519_SHA256_LIBSSH,
 #endif
     ID_EXTINFO_S, /* Pseudo-KEX to indicate server extensions. */
     ID_EXTINFO_C, /* Pseudo-KEX to indicate client extensions. */