crypto_symmetric.c

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/*
     This file is part of GNUnet.
     Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2013 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.
    
     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
*/

#include "platform.h"
#include "gnunet_crypto_lib.h"
#include <gcrypt.h>

#define LOG(kind,...) GNUNET_log_from (kind, "util-crypto-symmetric", __VA_ARGS__)

void
GNUNET_CRYPTO_symmetric_create_session_key (struct GNUNET_CRYPTO_SymmetricSessionKey *key)
{
  gcry_randomize (key->aes_key,
                  GNUNET_CRYPTO_AES_KEY_LENGTH,
                  GCRY_STRONG_RANDOM);
  gcry_randomize (key->twofish_key,
                  GNUNET_CRYPTO_AES_KEY_LENGTH,
                  GCRY_STRONG_RANDOM);
}


static int
setup_cipher_aes (gcry_cipher_hd_t *handle,
                  const struct GNUNET_CRYPTO_SymmetricSessionKey *sessionkey,
                  const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv)
{
  int rc;

  GNUNET_assert (0 ==
                 gcry_cipher_open (handle, GCRY_CIPHER_AES256,
                                   GCRY_CIPHER_MODE_CFB, 0));
  rc = gcry_cipher_setkey (*handle,
                           sessionkey->aes_key,
                           sizeof (sessionkey->aes_key));
  GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
  rc = gcry_cipher_setiv (*handle,
                          iv->aes_iv,
                          sizeof (iv->aes_iv));
  GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
  return GNUNET_OK;
}


static int
setup_cipher_twofish (gcry_cipher_hd_t *handle,
                      const struct GNUNET_CRYPTO_SymmetricSessionKey *sessionkey,
                      const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv)
{
  int rc;

  GNUNET_assert (0 ==
                 gcry_cipher_open (handle, GCRY_CIPHER_TWOFISH,
                                   GCRY_CIPHER_MODE_CFB, 0));
  rc = gcry_cipher_setkey (*handle,
                           sessionkey->twofish_key,
                           sizeof (sessionkey->twofish_key));
  GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
  rc = gcry_cipher_setiv (*handle,
                          iv->twofish_iv,
                          sizeof (iv->twofish_iv));
  GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
  return GNUNET_OK;
}


ssize_t
GNUNET_CRYPTO_symmetric_encrypt (const void *block,
                                 size_t size,
                                 const struct GNUNET_CRYPTO_SymmetricSessionKey *sessionkey,
                                 const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv,
                                 void *result)
{
  gcry_cipher_hd_t handle;
  char tmp[size];

  if (GNUNET_OK != setup_cipher_aes (&handle, sessionkey, iv))
    return -1;
  GNUNET_assert (0 == gcry_cipher_encrypt (handle, tmp, size, block, size));
  gcry_cipher_close (handle);
  if (GNUNET_OK != setup_cipher_twofish (&handle, sessionkey, iv))
    return -1;
  GNUNET_assert (0 == gcry_cipher_encrypt (handle, result, size, tmp, size));
  gcry_cipher_close (handle);
  memset (tmp, 0, sizeof (tmp));
  return size;
}


ssize_t
GNUNET_CRYPTO_symmetric_decrypt (const void *block,
                                 size_t size,
                                 const struct GNUNET_CRYPTO_SymmetricSessionKey *sessionkey,
                                 const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv,
                                 void *result)
{
  gcry_cipher_hd_t handle;
  char tmp[size];

  if (GNUNET_OK != setup_cipher_twofish (&handle, sessionkey, iv))
    return -1;
  GNUNET_assert (0 == gcry_cipher_decrypt (handle, tmp, size, block, size));
  gcry_cipher_close (handle);
  if (GNUNET_OK != setup_cipher_aes (&handle, sessionkey, iv))
    return -1;
  GNUNET_assert (0 == gcry_cipher_decrypt (handle, result, size, tmp, size));
  gcry_cipher_close (handle);
  memset (tmp, 0, sizeof (tmp));
  return size;
}


void
GNUNET_CRYPTO_symmetric_derive_iv (struct GNUNET_CRYPTO_SymmetricInitializationVector *iv,
                                   const struct GNUNET_CRYPTO_SymmetricSessionKey *skey,
                                   const void *salt,
                                   size_t salt_len,
                                   ...)
{
  va_list argp;

  va_start (argp, salt_len);
  GNUNET_CRYPTO_symmetric_derive_iv_v (iv, skey, salt, salt_len, argp);
  va_end (argp);
}


void
GNUNET_CRYPTO_symmetric_derive_iv_v (struct GNUNET_CRYPTO_SymmetricInitializationVector *iv,
                                     const struct GNUNET_CRYPTO_SymmetricSessionKey *skey,
                                     const void *salt,
                                     size_t salt_len,
                                     va_list argp)
{
  char aes_salt[salt_len + 4];
  char twofish_salt[salt_len + 4];

  GNUNET_memcpy (aes_salt, salt, salt_len);
  GNUNET_memcpy (&aes_salt[salt_len], "AES!", 4);
  GNUNET_memcpy (twofish_salt, salt, salt_len);
  GNUNET_memcpy (&twofish_salt[salt_len], "FISH", 4);
  GNUNET_CRYPTO_kdf_v (iv->aes_iv,
                       sizeof (iv->aes_iv),
                       aes_salt,
                       salt_len + 4,
                       skey->aes_key,
                       sizeof (skey->aes_key),
                       argp);
  GNUNET_CRYPTO_kdf_v (iv->twofish_iv,
                       sizeof (iv->twofish_iv),
                       twofish_salt,
                       salt_len + 4,
                       skey->twofish_key,
                       sizeof (skey->twofish_key),
                       argp);
}

/* end of crypto_symmetric.c */