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/*
This file is part of TALER
(C) 2014 Christian Grothoff (and other contributing authors)
TALER is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
TALER 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 General Public License for more details.
You should have received a copy of the GNU General Public License along with
TALER; see the file COPYING. If not, If not, see <http://www.gnu.org/licenses/>
*/
/**
* @file crypto.c
* @brief Cryptographic utility functions
* @author Sree Harsha Totakura <sreeharsha@totakura.in>
* @author Florian Dold
* @author Benedikt Mueller
*/
#include "platform.h"
#include "taler_util.h"
#include <gnunet/gnunet_common.h>
#include <gnunet/gnunet_util_lib.h>
#include <gcrypt.h>
#define CURVE "Ed25519"
static void
fatal_error_handler (void *cls, int wtf, const char *msg)
{
LOG_ERROR("Fatal error in Gcrypt: %s\n", msg);
abort();
}
/**
* Initialize Gcrypt library.
*/
void
TALER_gcrypt_init()
{
gcry_set_fatalerror_handler (&fatal_error_handler, NULL);
TALER_assert_as(gcry_check_version(NEED_LIBGCRYPT_VERSION),
"libgcrypt version mismatch");
/* Disable secure memory. */
gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
}
/**
* Derive symmetric key material for refresh operations from
* a given shared secret.
*
* @param secret the shared secret
* @param[out] iv set to initialization vector
* @param[out] skey set to session key
*/
static void
derive_refresh_key (const struct GNUNET_HashCode *secret,
struct GNUNET_CRYPTO_SymmetricInitializationVector *iv,
struct GNUNET_CRYPTO_SymmetricSessionKey *skey)
{
static const char ctx_key[] = "taler-key-skey";
static const char ctx_iv[] = "taler-key-iv";
GNUNET_assert (GNUNET_YES ==
GNUNET_CRYPTO_kdf (skey, sizeof (struct GNUNET_CRYPTO_SymmetricSessionKey),
ctx_key, strlen (ctx_key),
secret, sizeof (struct GNUNET_HashCode),
NULL, 0));
GNUNET_assert (GNUNET_YES ==
GNUNET_CRYPTO_kdf (iv, sizeof (struct GNUNET_CRYPTO_SymmetricInitializationVector),
ctx_iv, strlen (ctx_iv),
secret, sizeof (struct GNUNET_HashCode),
NULL, 0));
}
int
TALER_refresh_decrypt (const void *input,
size_t input_size,
const struct GNUNET_HashCode *secret,
void *result)
{
struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
struct GNUNET_CRYPTO_SymmetricSessionKey skey;
derive_refresh_key (secret, &iv, &skey);
return GNUNET_CRYPTO_symmetric_decrypt (input, input_size, &skey, &iv, result);
}
int
TALER_refresh_encrypt (const void *input,
size_t input_size,
const struct GNUNET_HashCode *secret,
void *result)
{
struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
struct GNUNET_CRYPTO_SymmetricSessionKey skey;
derive_refresh_key (secret, &iv, &skey);
return GNUNET_CRYPTO_symmetric_encrypt (input, input_size, &skey, &iv, result);
}
/* end of crypto.c */
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