generic_xts.h

/*
 * Copyright (C) 2008, Damien Miller
 * Copyright (C) 2011, Alex Hornung
 *
 * Permission to use, copy, and modify this software with or without fee
 * is hereby granted, provided that this entire notice is included in
 * all copies of any software which is or includes a copy or
 * modification of this software.
 * You may use this code under the GNU public license if you so wish. Please
 * contribute changes back to the authors under this freer than GPL license
 * so that we may further the use of strong encryption without limitations to
 * all.
 *
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
 * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
 * PURPOSE.
 */

#include <inttypes.h>
#define XTS_MAX_BLOCKSIZE	16
#define XTS_IVSIZE		8
#define XTS_ALPHA		0x87	/* GF(2^128) generator polynomial */

typedef int (*encrypt_decrypt_fn)(void *, size_t, const uint8_t *, uint8_t *);
typedef int (*set_key_fn)(void **, void *, void *, const uint8_t *, int);
typedef int (*zero_key_fn)(void **);


struct xts_ctx {
	encrypt_decrypt_fn	encrypt_fn;
	encrypt_decrypt_fn	decrypt_fn;
	set_key_fn		set_key_fn;
	zero_key_fn		zero_key_fn;

	void		*ctx1;
	void		*ctx2;
	uint8_t		tweak[XTS_MAX_BLOCKSIZE];
	uint32_t	blk_sz;
};

int xts_init(struct xts_ctx *ctxp, void *arg1, void *arg2, set_key_fn set_key_fn,
    zero_key_fn zero_key_fn, encrypt_decrypt_fn encrypt_fn,
    encrypt_decrypt_fn decrypt_fn, uint32_t blk_sz, uint8_t *key, int len);
int xts_encrypt(struct xts_ctx *ctx, uint8_t *data, size_t len, uint8_t *iv);
int xts_decrypt(struct xts_ctx *ctx, uint8_t *data, size_t len, uint8_t *iv);
int xts_uninit(struct xts_ctx *ctxp);