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/*
This file is part of TALER
Copyright (C) 2014, 2015 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 include/taler_crypto_lib.h
* @brief taler-specific crypto functions
* @author Sree Harsha Totakura <sreeharsha@totakura.in>
*/
#ifndef TALER_CRYPTO_LIB_H
#define TALER_CRYPTO_LIB_H
#include <gnunet/gnunet_util_lib.h>
#include <gcrypt.h>
/* ****************** Coin crypto primitives ************* */
/**
* Public information about a coin (including the public key
* of the coin, the denomination key and the signature with
* the denomination key).
*/
struct TALER_CoinPublicInfo
{
/**
* The coin's public key.
*/
struct GNUNET_CRYPTO_EcdsaPublicKey coin_pub;
/**
* Public key representing the denomination of the coin
* that is being deposited.
*/
struct GNUNET_CRYPTO_rsa_PublicKey *denom_pub;
/**
* (Unblinded) signature over @e coin_pub with @e denom_pub,
* which demonstrates that the coin is valid.
*/
struct GNUNET_CRYPTO_rsa_Signature *denom_sig;
};
/**
* Check if a coin is valid; that is, whether the denomination key exists,
* is not expired, and the signature is correct.
*
* @param coin_public_info the coin public info to check for validity
* @return #GNUNET_YES if the coin is valid,
* #GNUNET_NO if it is invalid
* #GNUNET_SYSERROR if an internal error occured
*/
int
TALER_test_coin_valid (const struct TALER_CoinPublicInfo *coin_public_info);
/* ****************** Refresh crypto primitives ************* */
/**
* Secret used to decrypt the key to decrypt link secrets.
*/
struct TALER_TransferSecret
{
/**
* Secret used to encrypt/decrypt the `struct TALER_LinkSecret`.
* Must be (currently) a hash as this is what
* #GNUNET_CRYPTO_ecc_ecdh() returns to us.
*/
struct GNUNET_HashCode key;
};
/**
* Secret used to decrypt refresh links.
*/
struct TALER_LinkSecret
{
/**
* Secret used to decrypt the refresh link data.
*/
char key[sizeof (struct GNUNET_HashCode)];
};
/**
* Encrypted secret used to decrypt refresh links.
*/
struct TALER_EncryptedLinkSecret
{
/**
* Encrypted secret, must be the given size!
*/
char enc[sizeof (struct TALER_LinkSecret)];
};
/**
* Representation of an encrypted refresh link.
*/
struct TALER_RefreshLinkEncrypted
{
/**
* Encrypted blinding key with @e blinding_key_enc_size bytes,
* must be allocated at the end of this struct.
*/
const char *blinding_key_enc;
/**
* Number of bytes in @e blinding_key_enc.
*/
size_t blinding_key_enc_size;
/**
* Encrypted private key of the coin.
*/
char coin_priv_enc[sizeof (struct GNUNET_CRYPTO_EcdsaPrivateKey)];
};
/**
* Representation of an refresh link in cleartext.
*/
struct TALER_RefreshLinkDecrypted
{
/**
* Private key of the coin.
*/
struct GNUNET_CRYPTO_EcdsaPrivateKey coin_priv;
/**
* Blinding key with @e blinding_key_enc_size bytes.
*/
struct GNUNET_CRYPTO_rsa_BlindingKey *blinding_key;
};
/**
* Use the @a trans_sec (from ECDHE) to decrypt the @a secret_enc
* to obtain the @a secret to decrypt the linkage data.
*
* @param secret_enc encrypted secret
* @param trans_sec transfer secret
* @param secret shared secret for refresh link decryption
* @return #GNUNET_OK on success
*/
int
TALER_transfer_decrypt (const struct TALER_EncryptedLinkSecret *secret_enc,
const struct TALER_TransferSecret *trans_sec,
struct TALER_LinkSecret *secret);
/**
* Use the @a trans_sec (from ECDHE) to encrypt the @a secret
* to obtain the @a secret_enc.
*
* @param secret shared secret for refresh link decryption
* @param trans_sec transfer secret
* @param secret_enc[out] encrypted secret
* @return #GNUNET_OK on success
*/
int
TALER_transfer_encrypt (const struct TALER_LinkSecret *secret,
const struct TALER_TransferSecret *trans_sec,
struct TALER_EncryptedLinkSecret *secret_enc);
/**
* Decrypt refresh link information.
*
* @param input encrypted refresh link data
* @param secret shared secret to use for decryption
* @return NULL on error
*/
struct TALER_RefreshLinkDecrypted *
TALER_refresh_decrypt (const struct TALER_RefreshLinkEncrypted *input,
const struct TALER_LinkSecret *secret);
/**
* Encrypt refresh link information.
*
* @param input plaintext refresh link data
* @param secret shared secret to use for encryption
* @return NULL on error (should never happen)
*/
struct TALER_RefreshLinkEncrypted *
TALER_refresh_encrypt (const struct TALER_RefreshLinkDecrypted *input,
const struct TALER_LinkSecret *secret);
/**
* Decode encrypted refresh link information from buffer.
*
* @param buf buffer with refresh link data
* @param buf_len number of bytes in @a buf
* @return NULL on error (@a buf_len too small)
*/
struct TALER_RefreshLinkEncrypted *
TALER_refresh_link_encrypted_decode (const char *buf,
size_t buf_len);
#endif
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