Extend AES minimal and rdseed examples by padelsbach · Pull Request #563 · wolfSSL/wolfssl-examples

padelsbach · 2026-03-17T19:51:18Z

Added minimal AESGCM example for encrypting a file
Separate rdseed example into its own directory with minimal user_settings.h
Minor fixes for DO178 compliance

tmael

Don't split aesgcm-rdseed.c into a separate file. The original design in aesgcm-minimal.c with
#ifdef for RDSEED was cleaner. If a separate rdseed directory is desired (for the user_settings.h +
Makefile targeting LynxOS-178), just have rdseed/Makefile build ../aesgcm-minimal.c with
-DWOLFSSL_USER_SETTINGS -I. rather than duplicating ~150 lines of identical code.

crypto/aes/rdseed/user_settings.h

crypto/aes/aesgcm-file-minimal.c

tmael · 2026-03-19T20:52:49Z

crypto/aes/aesgcm-file-encrypt-minimal.c

@@ -0,0 +1,206 @@
+/* aesgcm-file-encrypt-minimal.c


encrypt only, no decrypt: The file writes IV || TAG || ciphertext
but there's no corresponding decrypt function or example, which limits its usefulness. The existing
aesgcm-file-encrypt.c already handles both encrypt and decrypt for files. Why not update that file instead?

Todd asked specifically for this

I’m okay with having a standalone file if Todd asked for it. Did he also not ask for Decrypt function?

Not specifically. I added Decrypt() to the example.

padelsbach · 2026-03-19T22:32:53Z

Don't split aesgcm-rdseed.c into a separate file.

Todd specifically asked for a rdseed only example

tmael · 2026-03-20T01:20:06Z

crypto/aes/rdseed/aesgcm-rdseed.c

+/* I/O: redirect XPRINTF to stdio when available                             */
+/* ------------------------------------------------------------------------- */
+#ifndef XPRINTF
+    #include <stdio.h>


The second include (inside the XPRINTF fallback block) is redundant.

tmael · 2026-03-20T01:26:01Z

crypto/aes/aesgcm-minimal.c

+    int i;
    printf("%s: ", label);
-    for (word32 i = 0; i < sz; i++) {
+    for (i = 0; i < sz; i++) {


word32 i to match the fix in
aesgcm-file-encrypt-minimal.c

tmael · 2026-03-20T01:33:19Z

crypto/aes/aesgcm-file-encrypt-minimal.c

+        goto exit;
+    }
+
+    ret = Encrypt(key, iv, plaintext, (word32)plaintextSz, ciphertext, tag);


On a 64-bit system,
long is 8 bytes but word32 is 4 bytes. Files larger than ~4GB would silently truncate. Either document
the limitation or use word32 from the start with a size check - reject files that are too large or > (long) MAX_32BIT before calling Encrypt()

Good catch, converted to word32

tmael

Almost done. A couple of minor issues.

padelsbach marked this pull request as ready for review March 18, 2026 16:32

tmael requested changes Mar 19, 2026

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