int32_t psAesInitGCM(psAesGcm_t *ctx,
const unsigned char key[AES_MAXKEYLEN], uint8_t keylen)
{
/* Check that structure is 16bytes aligned: */
if (((uintptr_t) (const void *) (&(ctx->libSodiumCtx))) % 16 != 0)
{
psTraceCrypto("\nFAIL: libsodium structure not 16bytes aligned");
printf("FAIL: libsodium structure not 16bytes aligned %p", &(ctx->libSodiumCtx));
psAssert(0);
return PS_FAIL;
}
/* libsodium only supports aes256, not aes128 */
if (keylen != crypto_aead_aes256gcm_KEYBYTES)
{
psTraceCrypto("FAIL: libsodium-aes doesn't support this key length");
psAssert(keylen == crypto_aead_aes256gcm_KEYBYTES);
return PS_FAIL;
}
if (sodium_init() != 0)
{
/* libsodium is already initialized, no problem */
}
if (crypto_aead_aes256gcm_is_available() == 0)
{
psTraceCrypto("FAIL: libsodium-aes not supported");
psAssert(0);
return PS_FAIL;
}
memset(ctx, 0x00, sizeof(psAesGcm_t));
if (crypto_aead_aes256gcm_beforenm(&(ctx->libSodiumCtx), key) != 0)
{
psTraceCrypto("FAIL: libsodium-aes init");
psAssert(0);
return PS_FAIL;
}
return PS_SUCCESS;
}
static void
aead_cipher_ctx_set_key(cipher_ctx_t *cipher_ctx, int enc)
{
const digest_type_t *md = mbedtls_md_info_from_string("SHA1");
if (md == NULL) {
FATAL("SHA1 Digest not found in crypto library");
}
int err = crypto_hkdf(md,
cipher_ctx->salt, cipher_ctx->cipher->key_len,
cipher_ctx->cipher->key, cipher_ctx->cipher->key_len,
(uint8_t *)SUBKEY_INFO, strlen(SUBKEY_INFO),
cipher_ctx->skey, cipher_ctx->cipher->key_len);
if (err) {
FATAL("Unable to generate subkey");
}
memset(cipher_ctx->nonce, 0, cipher_ctx->cipher->nonce_len);
/* cipher that don't use mbed TLS, just return */
if (cipher_ctx->cipher->method >= CHACHA20POLY1305IETF) {
return;
}
if (cipher_ctx->aes256gcm_ctx != NULL) {
if (crypto_aead_aes256gcm_beforenm(cipher_ctx->aes256gcm_ctx,
cipher_ctx->skey) != 0) {
FATAL("Cannot set libsodium cipher key");
}
return;
}
if (mbedtls_cipher_setkey(cipher_ctx->evp, cipher_ctx->skey,
cipher_ctx->cipher->key_len * 8, enc) != 0) {
FATAL("Cannot set mbed TLS cipher key");
}
if (mbedtls_cipher_reset(cipher_ctx->evp) != 0) {
FATAL("Cannot finish preparation of mbed TLS cipher context");
}
}
