serpent.h

/* Copyright (c) 2009, Markus Peloquin <markus@cs.wisc.edu>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS' AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
 * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

#ifndef FLUKS_SERPENT_H
#define FLUKS_SERPENT_H

#include <features.h>

#ifdef __cplusplus
#	include <cstddef>
#	include <cstdint>

	const size_t SERPENT_BLOCK = 16;
	const size_t SERPENT_KEYMIN = 16;
	const size_t SERPENT_KEYMAX = 32;
	const size_t SERPENT_KEYSTEP = 8;
#else
#	include <stddef.h>
#	include <stdint.h>

#	define SERPENT_BLOCK 16
#	define SERPENT_KEYMIN 16
#	define SERPENT_KEYMAX 32
#	define SERPENT_KEYSTEP 8
#endif


enum serpent_return {
	/** Key material not of correct length */
	SERPENT_BAD_KEY_MAT = -1,
	SERPENT_OKAY = 0
};

struct serpent_ctx {
	uint32_t	subkeys[33][4];
};

#ifdef __cplusplus
extern "C" {
#endif

/** Initialize a Serpent context.
 *
 * \param ctx	The context structure.
 * \param key	The key, big endian byte order.
 * \param sz	The size of the key in bytes.
 * \retval SERPENT_BAD_KEY_MAT	The key size is invalid.
 */
enum serpent_return
	serpent_init(struct serpent_ctx *ctx,
	    const uint8_t *key, size_t sz);

/** Encrypt a block of data.
 *
 * \param[in] ctx		The context structure.
 * \param[out] plaintext	The data to encrypt, big endian order.
 * \param[out] ciphertext	The encrypted data, big endian order.
 */
void	serpent_encrypt(const struct serpent_ctx *ctx,
	    const uint8_t plaintext[SERPENT_BLOCK],
	    uint8_t ciphertext[SERPENT_BLOCK]);

/** Decrypt a block of data.
 *
 * \param[in] ctx		The context structure.
 * \param[out] ciphertext	The data to decrypt, big endian order.
 * \param[out] plaintext	The decrypted data, big endian order.
 */
void	serpent_decrypt(const struct serpent_ctx *ctx,
	    const uint8_t ciphertext[SERPENT_BLOCK],
	    uint8_t plaintext[SERPENT_BLOCK]);

#ifdef __cplusplus
}
#endif

#endif