/*

 * Copyright (C) 2011-2012 Free Software Foundation, Inc.

 *

 * Author: Nikos Mavrogiannopoulos

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public License

 * as published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>

 *

 */

/*

 * The following code is an implementation of the AES-128-GCM cipher

 * using AESNI (without PCLMUL)

 */

#include "errors.h"

#include "gnutls_int.h"

#ifdef HAVE_LIBNETTLE

#include <gnutls/crypto.h>

#include "errors.h"

#include "aes-x86.h"

#include "x86-common.h"

#include <byteswap.h>

#include <nettle/gcm.h>

#include <nettle/version.h>

/* GCM mode 

 * It is used when the CPU doesn't include the PCLMUL instructions.

 */

struct gcm_x86_aes_ctx {

  struct GCM_CTX(AES_KEY) inner;

  size_t rekey_counter;

};

static void x86_aes_encrypt(const void *_ctx, size_t length, uint8_t *dst,

          const uint8_t *src)

{

  AES_KEY *ctx = (void *)_ctx;

  aesni_ecb_encrypt(src, dst, length, ctx, 1);

}

static void x86_aes128_set_encrypt_key(void *_ctx, const uint8_t *key)

{

  AES_KEY *ctx = _ctx;

  aesni_set_encrypt_key(key, 16 * 8, ctx);

}

static void x86_aes192_set_encrypt_key(void *_ctx, const uint8_t *key)

{

  AES_KEY *ctx = _ctx;

  aesni_set_encrypt_key(key, 24 * 8, ctx);

}

static void x86_aes256_set_encrypt_key(void *_ctx, const uint8_t *key)

{

  AES_KEY *ctx = _ctx;

  aesni_set_encrypt_key(key, 32 * 8, ctx);

}

static int aes_gcm_cipher_init(gnutls_cipher_algorithm_t algorithm, void **_ctx,

             int enc)

{

  /* we use key size to distinguish */

  if (algorithm != GNUTLS_CIPHER_AES_128_GCM &&

      algorithm != GNUTLS_CIPHER_AES_192_GCM &&

      algorithm != GNUTLS_CIPHER_AES_256_GCM)

    return GNUTLS_E_INVALID_REQUEST;

  *_ctx = gnutls_calloc(1, sizeof(struct gcm_x86_aes_ctx));

  if (*_ctx == NULL) {

    gnutls_assert();

    return GNUTLS_E_MEMORY_ERROR;

  }

  return 0;

}

static int aes_gcm_cipher_setkey(void *_ctx, const void *key, size_t length)

{

  struct gcm_x86_aes_ctx *ctx = _ctx;

  if (length == 16) {

    GCM_SET_KEY(&ctx->inner, x86_aes128_set_encrypt_key,

          x86_aes_encrypt, key);

  } else if (length == 24) {

    GCM_SET_KEY(&ctx->inner, x86_aes192_set_encrypt_key,

          x86_aes_encrypt, key);

  } else if (length == 32) {

    GCM_SET_KEY(&ctx->inner, x86_aes256_set_encrypt_key,

          x86_aes_encrypt, key);

  } else

    return GNUTLS_E_INVALID_REQUEST;

  ctx->rekey_counter = 0;

  return 0;

}

static int aes_gcm_setiv(void *_ctx, const void *iv, size_t iv_size)

{

  struct gcm_x86_aes_ctx *ctx = _ctx;

  if (iv_size != GCM_BLOCK_SIZE - 4)

    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  GCM_SET_IV(&ctx->inner, iv_size, iv);

  ctx->rekey_counter = 0;

  return 0;

}

static int aes_gcm_encrypt(void *_ctx, const void *src, size_t src_size,

         void *dst, size_t length)

{

  struct gcm_x86_aes_ctx *ctx = _ctx;

  int ret;

  if (unlikely(length < src_size))

    return gnutls_assert_val(GNUTLS_E_SHORT_MEMORY_BUFFER);

  ret = record_aes_gcm_encrypt_size(&ctx->rekey_counter, src_size);

  if (ret < 0) {

    return gnutls_assert_val(ret);

  }

  GCM_ENCRYPT(&ctx->inner, x86_aes_encrypt, src_size, dst, src);

  return 0;

}

static int aes_gcm_decrypt(void *_ctx, const void *src, size_t src_size,

         void *dst, size_t dst_size)

{

  struct gcm_x86_aes_ctx *ctx = _ctx;

  if (unlikely(dst_size < src_size))

    return gnutls_assert_val(GNUTLS_E_SHORT_MEMORY_BUFFER);

  GCM_DECRYPT(&ctx->inner, x86_aes_encrypt, src_size, dst, src);

  return 0;

}

static int aes_gcm_auth(void *_ctx, const void *src, size_t src_size)

{

  struct gcm_x86_aes_ctx *ctx = _ctx;

  GCM_UPDATE(&ctx->inner, src_size, src);

  return 0;

}

static void aes_gcm_tag(void *_ctx, void *tag, size_t tagsize)

{

  struct gcm_x86_aes_ctx *ctx = _ctx;

  uint8_t buffer[GCM_DIGEST_SIZE];

#if NETTLE_VERSION_MAJOR >= 4

  GCM_DIGEST(&ctx->inner, x86_aes_encrypt, buffer);

#else

  GCM_DIGEST(&ctx->inner, x86_aes_encrypt, tagsize, buffer);

#endif

  memcpy(tag, buffer, tagsize);

}

static void aes_gcm_deinit(void *_ctx)

{

  struct gcm_x86_aes_ctx *ctx = _ctx;

  zeroize_key(ctx, sizeof(*ctx));

  gnutls_free(ctx);

}

#include "aes-gcm-aead.h"

const gnutls_crypto_cipher_st _gnutls_aes_gcm_x86_aesni = {

  .init = aes_gcm_cipher_init,

  .setkey = aes_gcm_cipher_setkey,

  .setiv = aes_gcm_setiv,

  .aead_encrypt = aes_gcm_aead_encrypt,

  .aead_decrypt = aes_gcm_aead_decrypt,

  .encrypt = aes_gcm_encrypt,

  .decrypt = aes_gcm_decrypt,

  .deinit = aes_gcm_deinit,

  .tag = aes_gcm_tag,

  .auth = aes_gcm_auth,

};

#endif