OpenSSL versions >= 3.4 removed the default digest length for
SHAKE128; it must now be set as an additional context parameter. 

--- sntp/crypto.c.~1~	Tue May  7 04:21:35 2024
+++ sntp/crypto.c	Sat May  3 12:37:48 2025
@@ -91,6 +91,19 @@
 				macname);
 			goto mac_fail;
 		}
+#if OPENSSL_VERSION_NUMBER >= 0x30400000L
+		if (key_type == NID_shake128) {
+			OSSL_PARAM params[2];
+			static uint shakelen = SHAKE128_LENGTH;
+			params[0] = OSSL_PARAM_construct_uint("xoflen", &shakelen);
+			params[1] = OSSL_PARAM_construct_end();
+			if (!EVP_MD_CTX_set_params(ctx, params)) {
+				msyslog(LOG_ERR, "make_mac: MAC %s set_params failed.",
+				    macname);
+				goto mac_fail;
+			}
+		}
+#endif
 		if (!EVP_DigestUpdate(ctx, key_data, key_size)) {
 			msyslog(LOG_ERR, "make_mac: MAC %s Digest Update key failed.",
 				macname);
--- libntp/a_md5encrypt.c.~1~	Tue May  7 04:21:31 2024
+++ libntp/a_md5encrypt.c	Sat May  3 12:56:01 2025
@@ -65,6 +65,19 @@
 		return NULL;
 	}
 
+#if OPENSSL_VERSION_NUMBER >= 0x30400000L
+	if (nid == NID_shake128) {
+		OSSL_PARAM params[2];
+		static uint shakelen = SHAKE128_LENGTH;
+		params[0] = OSSL_PARAM_construct_uint("xoflen", &shakelen);
+		params[1] = OSSL_PARAM_construct_end();
+		if (!EVP_MD_CTX_set_params(digest_ctx, params)) {
+			msyslog(LOG_ERR, "get_md_ctx: MAC %s set_params failed.",
+			    "shake128");
+			return NULL;
+		}
+	}
+#endif
 	return digest_ctx;
 #endif	/* OPENSSL */
 }