addressing sig length questions (#1306)

* addressing sig length questions

Co-authored-by: Douglas Stebila <dstebila@users.noreply.github.com>

src/sig/sig.h

@@ -242,7 +242,7 @@ typedef struct OQS_SIG {
 	 * compile-time macros `OQS_SIG_*_length_*`.
 	 *
 	 * @param[out] signature The signature on the message represented as a byte string.
-	 * @param[out] signature_len The length of the signature.
+	 * @param[out] signature_len The actual length of the signature. May be smaller than `length_signature` for some algorithms since some algorithms have variable length signatures.
 	 * @param[in] message The message to sign represented as a byte string.
 	 * @param[in] message_len The length of the message to sign.
 	 * @param[in] secret_key The secret key represented as a byte string.

tests/speed_sig.c

@@ -52,6 +52,9 @@ static OQS_STATUS sig_speed_wrapper(const char *method_name, uint64_t duration,
 
 	if (printInfo) {
 		printf("public key bytes: %zu, secret key bytes: %zu, signature bytes: %zu\n", sig->length_public_key, sig->length_secret_key, sig->length_signature);
+		if (signature_len != sig->length_signature) {
+			printf("   Actual signature length returned (%zu) less than declared maximum signature length (%zu)\n", signature_len, sig->length_signature);
+		}
 	}
 
 	ret = OQS_SUCCESS;