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/*
This file is part of TALER
Copyright (C) 2014-2017 Taler Systems SA
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, see <http://www.gnu.org/licenses/>
*/
/**
* @file util/crypto.c
* @brief Cryptographic utility functions
* @author Sree Harsha Totakura <sreeharsha@totakura.in>
* @author Florian Dold
* @author Benedikt Mueller
* @author Christian Grothoff
*/
#include "platform.h"
#include "taler_util.h"
#include <gcrypt.h>
/**
* Function called by libgcrypt on serious errors.
* Prints an error message and aborts the process.
*
* @param cls NULL
* @param wtf unknown
* @param msg error message
*/
static void
fatal_error_handler (void *cls,
int wtf,
const char *msg)
{
(void) cls;
(void) wtf;
fprintf (stderr,
"Fatal error in libgcrypt: %s\n",
msg);
abort ();
}
/**
* Initialize libgcrypt.
*/
void __attribute__ ((constructor))
TALER_gcrypt_init ()
{
gcry_set_fatalerror_handler (&fatal_error_handler,
NULL);
if (! gcry_check_version (NEED_LIBGCRYPT_VERSION))
{
fprintf (stderr,
"libgcrypt version mismatch\n");
abort ();
}
/* Disable secure memory (we should never run on a system that
even uses swap space for memory). */
gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
}
enum GNUNET_GenericReturnValue
TALER_test_coin_valid (const struct TALER_CoinPublicInfo *coin_public_info,
const struct TALER_DenominationPublicKey *denom_pub)
{
struct TALER_CoinPubHash c_hash;
#if ENABLE_SANITY_CHECKS
struct TALER_DenominationHash d_hash;
TALER_denom_pub_hash (denom_pub,
&d_hash);
GNUNET_assert (0 ==
GNUNET_memcmp (&d_hash,
&coin_public_info->denom_pub_hash));
#endif
// FIXME-Oec: replace with function that
// also hashes the age vector if we have
// one!
GNUNET_CRYPTO_hash (&coin_public_info->coin_pub,
sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey),
&c_hash.hash);
if (GNUNET_OK !=
TALER_denom_pub_verify (denom_pub,
&coin_public_info->denom_sig,
&c_hash))
{
GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
"coin signature is invalid\n");
return GNUNET_NO;
}
return GNUNET_YES;
}
void
TALER_link_derive_transfer_secret (
const struct TALER_CoinSpendPrivateKeyP *coin_priv,
const struct TALER_TransferPrivateKeyP *trans_priv,
struct TALER_TransferSecretP *ts)
{
struct TALER_CoinSpendPublicKeyP coin_pub;
GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv->eddsa_priv,
&coin_pub.eddsa_pub);
GNUNET_assert (GNUNET_OK ==
GNUNET_CRYPTO_ecdh_eddsa (&trans_priv->ecdhe_priv,
&coin_pub.eddsa_pub,
&ts->key));
}
void
TALER_link_reveal_transfer_secret (
const struct TALER_TransferPrivateKeyP *trans_priv,
const struct TALER_CoinSpendPublicKeyP *coin_pub,
struct TALER_TransferSecretP *transfer_secret)
{
GNUNET_assert (GNUNET_OK ==
GNUNET_CRYPTO_ecdh_eddsa (&trans_priv->ecdhe_priv,
&coin_pub->eddsa_pub,
&transfer_secret->key));
}
void
TALER_link_recover_transfer_secret (
const struct TALER_TransferPublicKeyP *trans_pub,
const struct TALER_CoinSpendPrivateKeyP *coin_priv,
struct TALER_TransferSecretP *transfer_secret)
{
GNUNET_assert (GNUNET_OK ==
GNUNET_CRYPTO_eddsa_ecdh (&coin_priv->eddsa_priv,
&trans_pub->ecdhe_pub,
&transfer_secret->key));
}
void
TALER_planchet_setup_refresh (const struct TALER_TransferSecretP *secret_seed,
uint32_t coin_num_salt,
struct TALER_PlanchetSecretsP *ps)
{
uint32_t be_salt = htonl (coin_num_salt);
GNUNET_assert (GNUNET_OK ==
GNUNET_CRYPTO_kdf (ps,
sizeof (*ps),
&be_salt,
sizeof (be_salt),
secret_seed,
sizeof (*secret_seed),
"taler-coin-derivation",
strlen ("taler-coin-derivation"),
NULL, 0));
}
void
cs_blinding_seed_derive (const struct
TALER_CoinSpendPrivateKeyP *coin_priv,
const struct GNUNET_CRYPTO_CsRPublic r_pub[2],
struct GNUNET_CRYPTO_CsNonce *blind_seed)
{
GNUNET_assert (GNUNET_YES ==
GNUNET_CRYPTO_hkdf (blind_seed,
sizeof (*blind_seed),
GCRY_MD_SHA512,
GCRY_MD_SHA256,
"bseed",
strlen ("bseed"),
coin_priv,
sizeof(*coin_priv),
r_pub,
sizeof(struct GNUNET_CRYPTO_CsRPublic) * 2,
NULL,
0));
}
void
TALER_cs_withdraw_nonce_derive (const struct
TALER_CoinSpendPrivateKeyP *coin_priv,
struct TALER_CsNonce *nonce)
{
GNUNET_assert (GNUNET_YES ==
GNUNET_CRYPTO_hkdf (nonce,
sizeof (*nonce),
GCRY_MD_SHA512,
GCRY_MD_SHA256,
"n",
strlen ("n"),
coin_priv,
sizeof(*coin_priv),
NULL,
0));
}
void
TALER_cs_withdraw_nonce_generate (struct TALER_CsNonce *nonce)
{
GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_STRONG,
nonce,
sizeof (*nonce));
}
void
TALER_planchet_blinding_secret_create (struct TALER_PlanchetSecretsP *ps,
const struct
TALER_ExchangeWithdrawValues *alg_values)
{
switch (alg_values->cipher)
{
case TALER_DENOMINATION_INVALID:
GNUNET_break (0);
return;
case TALER_DENOMINATION_RSA:
GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_STRONG,
&ps->blinding_key.rsa_bks,
sizeof (struct
GNUNET_CRYPTO_RsaBlindingKeySecret));
return;
case TALER_DENOMINATION_CS:
{
cs_blinding_seed_derive (&ps->coin_priv,
alg_values->details.cs_values.r_pub.r_pub,
&ps->blinding_key.nonce);
return;
}
default:
GNUNET_break (0);
}
}
/**
* @brief setup a random planchet
* In Case of RSA planchet, the bks gets set
* In Case of Clause Schnorr this will be set in future
*/
void
TALER_planchet_setup_random (struct TALER_PlanchetSecretsP *ps,
const struct
TALER_ExchangeWithdrawValues *alg_values)
{
GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_STRONG,
&ps->coin_priv,
sizeof (struct TALER_CoinSpendPrivateKeyP));
switch (alg_values->cipher)
{
case TALER_DENOMINATION_INVALID:
GNUNET_break (0);
return;
case TALER_DENOMINATION_RSA:
TALER_planchet_blinding_secret_create (ps,
alg_values);
return;
case TALER_DENOMINATION_CS:
// Will be set in a later stage for Clause Blind Schnorr Scheme
return;
default:
GNUNET_break (0);
}
}
enum GNUNET_GenericReturnValue
TALER_planchet_prepare (const struct TALER_DenominationPublicKey *dk,
const struct TALER_ExchangeWithdrawValues *alg_values,
struct TALER_PlanchetSecretsP *ps,
struct TALER_CoinPubHash *c_hash,
struct TALER_PlanchetDetail *pd)
{
struct TALER_CoinSpendPublicKeyP coin_pub;
GNUNET_assert (alg_values->cipher == dk->cipher);
GNUNET_CRYPTO_eddsa_key_get_public (&ps->coin_priv.eddsa_priv,
&coin_pub.eddsa_pub);
switch (dk->cipher)
{
case TALER_DENOMINATION_RSA:
if (GNUNET_OK !=
TALER_denom_blind (dk,
&ps->blinding_key,
NULL, /* FIXME-Oec */
&coin_pub,
alg_values,
c_hash,
&pd->blinded_planchet))
{
GNUNET_break (0);
return GNUNET_SYSERR;
}
break;
case TALER_DENOMINATION_CS:
if (GNUNET_OK !=
TALER_denom_blind (dk,
&ps->blinding_key,
NULL, /* FIXME-Oec */
&coin_pub,
alg_values,
c_hash,
&pd->blinded_planchet))
{
GNUNET_break (0);
return GNUNET_SYSERR;
}
break;
default:
GNUNET_break (0);
return GNUNET_SYSERR;
}
pd->blinded_planchet.cipher = dk->cipher;
TALER_denom_pub_hash (dk,
&pd->denom_pub_hash);
return GNUNET_OK;
}
void
TALER_blinded_planchet_free (struct TALER_BlindedPlanchet *blinded_planchet)
{
switch (blinded_planchet->cipher)
{
case TALER_DENOMINATION_RSA:
GNUNET_free (blinded_planchet->details.rsa_blinded_planchet.blinded_msg);
break;
case TALER_DENOMINATION_CS:
// nothing to do for CS
break;
default:
GNUNET_break (0);
}
}
enum GNUNET_GenericReturnValue
TALER_planchet_to_coin (const struct TALER_DenominationPublicKey *dk,
const struct
TALER_BlindedDenominationSignature *blind_sig,
const struct TALER_PlanchetSecretsP *ps,
const struct TALER_CoinPubHash *c_hash,
const struct TALER_ExchangeWithdrawValues *alg_values,
struct TALER_FreshCoin *coin)
{
struct TALER_DenominationSignature sig;
if (dk->cipher != blind_sig->cipher
&& dk->cipher != alg_values->cipher)
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
switch (dk->cipher)
{
case TALER_DENOMINATION_RSA:
if (GNUNET_OK !=
TALER_denom_sig_unblind (&sig,
blind_sig,
&ps->blinding_key,
dk))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
break;
case TALER_DENOMINATION_CS:
{
struct GNUNET_CRYPTO_CsC c[2];
struct GNUNET_CRYPTO_CsBlindingSecret bs[2];
struct TALER_DenominationCsPublicR r_pub_blind;
GNUNET_CRYPTO_cs_blinding_secrets_derive (&ps->blinding_key.nonce, bs);
GNUNET_CRYPTO_cs_calc_blinded_c (bs,
alg_values->details.cs_values.r_pub.r_pub,
&dk->details.cs_public_key,
&c_hash->hash,
sizeof(struct GNUNET_HashCode),
c,
r_pub_blind.r_pub);
sig.details.cs_signature.r_point
= r_pub_blind.r_pub[blind_sig->details.blinded_cs_answer.b];
if (GNUNET_OK !=
TALER_denom_sig_unblind (&sig,
blind_sig,
&ps->blinding_key,
dk))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
break;
}
default:
GNUNET_break (0);
return GNUNET_SYSERR;
}
if (GNUNET_OK !=
TALER_denom_pub_verify (dk,
&sig,
c_hash))
{
GNUNET_break_op (0);
TALER_denom_sig_free (&sig);
return GNUNET_SYSERR;
}
coin->sig = sig;
coin->coin_priv = ps->coin_priv;
return GNUNET_OK;
}
void
TALER_refresh_get_commitment (struct TALER_RefreshCommitmentP *rc,
uint32_t kappa,
uint32_t num_new_coins,
const struct TALER_RefreshCommitmentEntry *rcs,
const struct TALER_CoinSpendPublicKeyP *coin_pub,
const struct TALER_Amount *amount_with_fee)
{
struct GNUNET_HashContext *hash_context;
hash_context = GNUNET_CRYPTO_hash_context_start ();
/* first, iterate over transfer public keys for hash_context */
for (unsigned int i = 0; i<kappa; i++)
{
GNUNET_CRYPTO_hash_context_read (hash_context,
&rcs[i].transfer_pub,
sizeof (struct TALER_TransferPublicKeyP));
}
/* next, add all of the hashes from the denomination keys to the
hash_context */
for (unsigned int i = 0; i<num_new_coins; i++)
{
struct TALER_DenominationHash denom_hash;
/* The denomination keys should / must all be identical regardless
of what offset we use, so we use [0]. */
GNUNET_assert (kappa > 0); /* sanity check */
TALER_denom_pub_hash (rcs[0].new_coins[i].dk,
&denom_hash);
GNUNET_CRYPTO_hash_context_read (hash_context,
&denom_hash,
sizeof (denom_hash));
}
/* next, add public key of coin and amount being refreshed */
{
struct TALER_AmountNBO melt_amountn;
GNUNET_CRYPTO_hash_context_read (hash_context,
coin_pub,
sizeof (struct TALER_CoinSpendPublicKeyP));
TALER_amount_hton (&melt_amountn,
amount_with_fee);
GNUNET_CRYPTO_hash_context_read (hash_context,
&melt_amountn,
sizeof (struct TALER_AmountNBO));
}
/* finally, add all the envelopes */
for (unsigned int i = 0; i<kappa; i++)
{
const struct TALER_RefreshCommitmentEntry *rce = &rcs[i];
for (unsigned int j = 0; j<num_new_coins; j++)
{
const struct TALER_RefreshCoinData *rcd = &rce->new_coins[j];
GNUNET_CRYPTO_hash_context_read (hash_context,
rcd->coin_ev,
rcd->coin_ev_size);
}
}
/* Conclude */
GNUNET_CRYPTO_hash_context_finish (hash_context,
&rc->session_hash);
}
enum GNUNET_GenericReturnValue
TALER_coin_ev_hash (const struct TALER_BlindedPlanchet *blinded_planchet,
struct TALER_BlindedCoinHash *bch)
{
switch (blinded_planchet->cipher)
{
case TALER_DENOMINATION_RSA:
GNUNET_CRYPTO_hash (
blinded_planchet->details.rsa_blinded_planchet.blinded_msg,
blinded_planchet->details.rsa_blinded_planchet.blinded_msg_size,
&bch->hash);
return GNUNET_OK;
case TALER_DENOMINATION_CS:
GNUNET_CRYPTO_hash (
&blinded_planchet->details.cs_blinded_planchet.nonce,
sizeof (blinded_planchet->details.cs_blinded_planchet.nonce),
&bch->hash);
return GNUNET_OK;
default:
GNUNET_break (0);
return GNUNET_SYSERR;
}
}
void
TALER_coin_pub_hash (const struct TALER_CoinSpendPublicKeyP *coin_pub,
const struct TALER_AgeHash *age_commitment_hash,
struct TALER_CoinPubHash *coin_h)
{
if (NULL == age_commitment_hash)
{
/* No age commitment was set */
GNUNET_CRYPTO_hash (&coin_pub->eddsa_pub,
sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey),
&coin_h->hash);
}
else
{
/* Coin comes with age commitment. Take the hash of the age commitment
* into account */
const size_t key_s = sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey);
const size_t age_s = sizeof(struct TALER_AgeHash);
char data[key_s + age_s];
GNUNET_memcpy (&data[0],
&coin_pub->eddsa_pub,
key_s);
GNUNET_memcpy (&data[key_s],
age_commitment_hash,
age_s);
GNUNET_CRYPTO_hash (&data,
key_s + age_s,
&coin_h->hash);
}
}
/* end of crypto.c */
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