static int
myaes_gcm_decrypt(void *_ctx,
const void *nonce, size_t nonce_size,
const void *auth, size_t auth_size,
size_t tag_size,
const void *encr, size_t encr_size,
void *plain, size_t plain_size)
{
uint8_t tag[16];
struct myaes_gcm_ctx *ctx = _ctx;
if (encr_size < tag_size)
return GNUTLS_E_DECRYPTION_FAILED;
aead_used++;
gcm_aes128_set_iv(&ctx->aes, nonce_size, nonce);
gcm_aes128_update(&ctx->aes, auth_size, auth);
encr_size -= tag_size;
gcm_aes128_decrypt(&ctx->aes, encr_size, plain, encr);
gcm_aes128_digest(&ctx->aes, tag_size, tag);
if (gnutls_memcmp(((uint8_t*)encr)+encr_size, tag, tag_size) != 0)
return GNUTLS_E_DECRYPTION_FAILED;
return 0;
}
static int
myaes_gcm_encrypt(void *_ctx,
const void *nonce, size_t nonce_size,
const void *auth, size_t auth_size,
size_t tag_size,
const void *plain, size_t plain_size,
void *encr, size_t encr_size)
{
/* proper AEAD cipher */
struct myaes_gcm_ctx *ctx = _ctx;
if (encr_size < plain_size + tag_size)
return GNUTLS_E_SHORT_MEMORY_BUFFER;
aead_used++;
gcm_aes128_set_iv(&ctx->aes, nonce_size, nonce);
gcm_aes128_update(&ctx->aes, auth_size, auth);
gcm_aes128_encrypt(&ctx->aes, plain_size, encr, plain);
gcm_aes128_digest(&ctx->aes, tag_size, ((uint8_t*)encr) + plain_size);
return 0;
}
static void
test_gcm_hash (const struct tstring *msg, const struct tstring *ref)
{
struct gcm_aes128_ctx ctx;
const uint8_t z16[16] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 };
uint8_t digest[16];
ASSERT (ref->length == sizeof(digest));
gcm_aes128_set_key (&ctx, z16);
gcm_aes128_set_iv (&ctx, 16, z16);
gcm_aes128_update (&ctx, msg->length, msg->data);
gcm_aes128_digest (&ctx, sizeof(digest), digest);
if (!MEMEQ (ref->length, ref->data, digest))
{
fprintf (stderr, "gcm_hash failed, msg: %s\nOutput: ", msg->data);
print_hex (16, digest);
fprintf(stderr, "Expected:");
tstring_print_hex(ref);
fprintf(stderr, "\n");
FAIL();
}
}
