touch-ups:

- shrink ech interop workflow
- x448 macro now unused in hpke WOLFSSL_LOCAL functions
- bug fixes in added tests

src/ssl_ech.c

@@ -35,7 +35,7 @@ int wolfSSL_CTX_GenerateEchConfig(WOLFSSL_CTX* ctx, const char* publicName,
 {
     int ret = 0;
     WOLFSSL_EchConfig* newConfig;
-    word16 encLen = sizeof(newConfig->receiverPubkey);
+    word16 encLen = HPKE_Npk_MAX;
 #ifdef WOLFSSL_SMALL_STACK
     Hpke* hpke = NULL;
     WC_RNG* rng;

src/tls.c

@@ -13260,6 +13260,10 @@ static int TLSX_ECH_Use(WOLFSSL_EchConfig* echConfig, TLSX** extensions,
     ech->configId = echConfig->configId;
     /* encLen */
     ech->encLen = wc_HpkeKemGetEncLen(echConfig->kemId);
+    if (ech->encLen == 0) {
+        XFREE(ech, heap, DYNAMIC_TYPE_TMP_BUFFER);
+        return BAD_FUNC_ARG;
+    }
     /* setup hpke */
     ech->hpke = (Hpke*)XMALLOC(sizeof(Hpke), heap, DYNAMIC_TYPE_TMP_BUFFER);
     if (ech->hpke == NULL) {