[u/mdw/catacomb] / cfb-def.h

/* -*-c-*-
 *
 * $Id: cfb-def.h,v 1.5 2004/04/08 01:36:15 mdw Exp $
 *
 * Definitions for ciphertext feedback mode
 *
 * (c) 1999 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * Catacomb 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 Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

#ifndef CATACOMB_CFB_DEF_H
#define CATACOMB_CFB_DEF_H

#ifdef __cplusplus
  extern "C" {
#endif

/*----- Header files ------------------------------------------------------*/

#include <string.h>

#include <mLib/bits.h>
#include <mLib/sub.h>

#ifndef CATACOMB_ARENA_H
#  include "arena.h"
#endif

#ifndef CATACOMB_BLKC_H
#  include "blkc.h"
#endif

#ifndef CATACOMB_GCIPHER_H
#  include "gcipher.h"
#endif

#ifndef CATACOMB_PARANOIA_H
#  include "paranoia.h"
#endif

#ifndef CATACOMB_PARANOIA_H
#  include "paranoia.h"
#endif

/*----- Macros ------------------------------------------------------------*/

/* --- @CFB_DEF@ --- *
 *
 * Arguments:	@PRE@, @pre@ = prefixes for the underlying block cipher
 *
 * Use:		Creates an implementation for CFB mode.
 */

#define CFB_DEF(PRE, pre)						\
									\
/* --- @pre_cfbgetiv@ --- *						\
 *									\
 * Arguments:	@const pre_cfbctx *ctx@ = pointer to CFB context block	\
 *		@void *iv@ = pointer to output data block		\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Reads the currently set IV.  Reading and setting an IV	\
 *		is not transparent to the cipher.  It will add a `step'	\
 *		which must be matched by a similar operation during	\
 *		decryption.						\
 */									\
									\
void pre##_cfbgetiv(const pre##_cfbctx *ctx, void *iv)			\
{									\
  octet *p = iv;							\
  unsigned off = ctx->off;						\
  unsigned rest = PRE##_BLKSZ - off;					\
  memcpy(p, ctx->iv + off, rest);					\
  memcpy(p + rest, ctx->iv, off);					\
}									\
									\
/* --- @pre_cfbsetiv@ --- *						\
 *									\
 * Arguments:	@pre_cfbctx *ctx@ = pointer to CFB context block	\
 *		@cnost void *iv@ = pointer to IV to set			\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Sets the IV to use for subsequent encryption.		\
 */									\
									\
void pre##_cfbsetiv(pre##_cfbctx *ctx, const void *iv)			\
{									\
  memcpy(ctx->iv, iv, PRE##_BLKSZ);					\
  ctx->off = PRE##_BLKSZ;						\
}									\
									\
/* --- @pre_cfbbdry@ --- *						\
 *									\
 * Arguments:	@pre_cfbctx *ctx@ = pointer to CFB context block	\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Inserts a boundary during encryption.  Successful	\
 *		decryption must place a similar boundary.		\
 */									\
									\
void pre##_cfbbdry(pre##_cfbctx *ctx)					\
{									\
  uint32 niv[PRE##_BLKSZ / 4];						\
  BLKC_LOAD(PRE, niv, ctx->iv);						\
  pre##_eblk(&ctx->ctx, niv, niv);					\
  BLKC_STORE(PRE, ctx->iv, niv);					\
  ctx->off = PRE##_BLKSZ;						\
  BURN(niv);								\
}									\
									\
/* --- @pre_cfbsetkey@ --- *						\
 *									\
 * Arguments:	@pre_cfbctx *ctx@ = pointer to CFB context block	\
 *		@const pre_ctx *k@ = pointer to cipher context		\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Sets the CFB context to use a different cipher key.	\
 */									\
									\
void pre##_cfbsetkey(pre##_cfbctx *ctx, const pre##_ctx *k)		\
{									\
  ctx->ctx = *k;							\
  ctx->off = PRE##_BLKSZ;						\
}									\
									\
/* --- @pre_cfbinit@ --- *						\
 *									\
 * Arguments:	@pre_cfbctx *ctx@ = pointer to cipher context		\
 *		@const void *key@ = pointer to the key buffer		\
 *		@size_t sz@ = size of the key				\
 *		@const void *iv@ = pointer to initialization vector	\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Initializes a CFB context ready for use.  You should	\
 *		ensure that the IV chosen is unique: reusing an IV will	\
 *		compromise the security of at least the first block	\
 *		encrypted.  This is equivalent to calls to @pre_init@,	\
 *		@pre_cfbsetkey@ and @pre_cfbsetiv@.			\
 */									\
									\
void pre##_cfbinit(pre##_cfbctx *ctx,					\
		     const void *key, size_t sz,			\
		     const void *iv)					\
{									\
  static const octet zero[PRE##_BLKSZ] = { 0 };				\
  pre##_init(&ctx->ctx, key, sz);					\
  pre##_cfbsetiv(ctx, iv ? iv : zero);					\
}									\
									\
/* --- @pre_cfbencrypt@ --- *						\
 *									\
 * Arguments:	@pre_cfbctx *ctx@ = pointer to CFB context block	\
 *		@const void *src@ = pointer to source data		\
 *		@void *dest@ = pointer to destination data		\
 *		@size_t sz@ = size of block to be encrypted		\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Encrypts a block with a block cipher in CFB mode.  The	\
 *		input block may be arbitrary in size.  CFB mode is not	\
 *		sensitive to block boundaries.				\
 */									\
									\
void pre##_cfbencrypt(pre##_cfbctx *ctx,				\
			const void *src, void *dest,			\
			size_t sz)					\
{									\
  const octet *s = src;							\
  octet *d = dest;							\
  unsigned off = ctx->off;						\
									\
  /* --- Empty blocks are trivial --- */				\
									\
  if (!sz)								\
    return;								\
									\
  /* --- If I can deal with the block from my buffer, do that --- */	\
									\
  if (sz < PRE##_BLKSZ - off)						\
    goto small;								\
									\
  /* --- Finish off what's left in my buffer --- */			\
									\
  while (off < PRE##_BLKSZ) {						\
    register octet x = *s++;						\
    *d++ = ctx->iv[off++] ^= x;						\
    sz--;								\
  }									\
									\
  /* --- Main encryption loop --- */					\
									\
  {									\
    uint32 iv[PRE##_BLKSZ / 4];						\
    BLKC_LOAD(PRE, iv, ctx->iv);					\
									\
    for (;;) {								\
      pre##_eblk(&ctx->ctx, iv, iv);					\
      if (sz < PRE##_BLKSZ)						\
	break;								\
      BLKC_XLOAD(PRE, iv, s);						\
      BLKC_STORE(PRE, d, iv);						\
      s += PRE##_BLKSZ;							\
      d += PRE##_BLKSZ;							\
      sz -= PRE##_BLKSZ;						\
    }									\
    off = 0;								\
    BLKC_STORE(PRE, ctx->iv, iv);					\
  }									\
									\
  /* --- Tidying up the tail end --- */					\
									\
  if (sz) {								\
  small:								\
    do {								\
      register octet x = *s++;						\
      *d++ = ctx->iv[off++] ^= x;					\
      sz--;								\
    } while (sz);							\
  }									\
									\
  /* --- Done --- */							\
									\
  ctx->off = off;							\
  return;								\
}									\
									\
/* --- @pre_cfbdecrypt@ --- *						\
 *									\
 * Arguments:	@pre_cfbctx *ctx@ = pointer to CFB context block	\
 *		@const void *src@ = pointer to source data		\
 *		@void *dest@ = pointer to destination data		\
 *		@size_t sz@ = size of block to be encrypted		\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Decrypts a block with a block cipher in CFB mode.  The	\
 *		input block may be arbitrary in size.  CFB mode is not	\
 *		sensitive to block boundaries.				\
 */									\
									\
void pre##_cfbdecrypt(pre##_cfbctx *ctx,				\
			const void *src, void *dest,			\
			size_t sz)					\
{									\
  const octet *s = src;							\
  octet *d = dest;							\
  unsigned off = ctx->off;						\
									\
  /* --- Empty blocks are trivial --- */				\
									\
  if (!sz)								\
    return;								\
									\
  /* --- If I can deal with the block from my buffer, do that --- */	\
									\
  if (sz < PRE##_BLKSZ - off)						\
    goto small;								\
									\
  /* --- Finish off what's left in my buffer --- */			\
									\
  while (off < PRE##_BLKSZ) {						\
    register octet x = *s++;						\
    *d++ = ctx->iv[off] ^ x;						\
    ctx->iv[off++] = x;							\
    sz--;								\
  }									\
									\
  /* --- Main encryption loop --- */					\
									\
  {									\
    uint32 iv[PRE##_BLKSZ / 4];						\
    BLKC_LOAD(PRE, iv, ctx->iv);					\
									\
    for (;;) {								\
      uint32 x[PRE##_BLKSZ / 4];					\
      pre##_eblk(&ctx->ctx, iv, iv);					\
      if (sz < PRE##_BLKSZ)						\
	break;								\
      BLKC_LOAD(PRE, x, s);						\
      BLKC_XSTORE(PRE, d, iv, x);					\
      BLKC_MOVE(PRE, iv, x);						\
      s += PRE##_BLKSZ;							\
      d += PRE##_BLKSZ;							\
      sz -= PRE##_BLKSZ;						\
    }									\
    off = 0;								\
    BLKC_STORE(PRE, ctx->iv, iv);					\
  }									\
									\
  /* --- Tidying up the tail end --- */					\
									\
  if (sz) {								\
  small:								\
    do {								\
      register octet x = *s++;						\
      *d++ = ctx->iv[off] ^ x;						\
      ctx->iv[off++] = x;						\
      sz--;								\
    } while (sz);							\
  }									\
									\
  /* --- Done --- */							\
									\
  ctx->off = off;							\
  return;								\
}									\
									\
/* --- Generic cipher interface --- */					\
									\
static const gcipher_ops gops;						\
									\
typedef struct gctx {							\
  gcipher c;								\
  pre##_cfbctx k;							\
} gctx;									\
									\
static gcipher *ginit(const void *k, size_t sz)				\
{									\
  gctx *g = S_CREATE(gctx);						\
  g->c.ops = &gops;							\
  pre##_cfbinit(&g->k, k, sz, 0);					\
  return (&g->c);							\
}									\
									\
static void gencrypt(gcipher *c, const void *s, void *t, size_t sz)	\
{									\
  gctx *g = (gctx *)c;							\
  pre##_cfbencrypt(&g->k, s, t, sz);					\
}									\
									\
static void gdecrypt(gcipher *c, const void *s, void *t, size_t sz)	\
{									\
  gctx *g = (gctx *)c;							\
  pre##_cfbdecrypt(&g->k, s, t, sz);					\
}									\
									\
static void gdestroy(gcipher *c)					\
{									\
  gctx *g = (gctx *)c;							\
  BURN(*g);								\
  S_DESTROY(g);								\
}									\
									\
static void gsetiv(gcipher *c, const void *iv)				\
{									\
  gctx *g = (gctx *)c;							\
  pre##_cfbsetiv(&g->k, iv);						\
}									\
									\
static void gbdry(gcipher *c)						\
{									\
  gctx *g = (gctx *)c;							\
  pre##_cfbbdry(&g->k);							\
}									\
									\
static const gcipher_ops gops = {					\
  &pre##_cfb,								\
  gencrypt, gdecrypt, gdestroy, gsetiv, gbdry				\
};									\
									\
const gccipher pre##_cfb = {						\
  #pre "-cfb", pre##_keysz, PRE##_BLKSZ,				\
  ginit									\
};									\
									\
CFB_TEST(PRE, pre)

/*----- Test rig ----------------------------------------------------------*/

#ifdef TEST_RIG

#include <stdio.h>

#include "daftstory.h"

/* --- @CFB_TEST@ --- *
 *
 * Arguments:	@PRE@, @pre@ = prefixes for block cipher definitions
 *
 * Use:		Standard test rig for CFB functions.
 */

#define CFB_TEST(PRE, pre)						\
									\
/* --- Initial plaintext for the test --- */				\
									\
static const octet text[] = TEXT;					\
									\
/* --- Key and IV to use --- */						\
									\
static const octet key[] = KEY;						\
static const octet iv[] = IV;						\
									\
/* --- Buffers for encryption and decryption output --- */		\
									\
static octet ct[sizeof(text)];						\
static octet pt[sizeof(text)];						\
									\
static void hexdump(const octet *p, size_t sz)				\
{									\
  const octet *q = p + sz;						\
  for (sz = 0; p < q; p++, sz++) {					\
    printf("%02x", *p);							\
    if ((sz + 1) % PRE##_BLKSZ == 0)					\
      putchar(':');							\
  }									\
}									\
									\
int main(void)								\
{									\
  size_t sz = 0, rest;							\
  pre##_cfbctx ctx;							\
  int status = 0;							\
  int done = 0;								\
  pre##_ctx k;								\
									\
  size_t keysz = PRE##_KEYSZ ?						\
    PRE##_KEYSZ : strlen((const char *)key);				\
									\
  fputs(#pre "-cfb: ", stdout);						\
									\
  pre##_init(&k, key, keysz);						\
  pre##_cfbsetkey(&ctx, &k);						\
									\
  while (sz <= sizeof(text)) {						\
    rest = sizeof(text) - sz;						\
    memcpy(ct, text, sizeof(text));					\
    pre##_cfbsetiv(&ctx, iv);						\
    pre##_cfbencrypt(&ctx, ct, ct, sz);					\
    pre##_cfbencrypt(&ctx, ct + sz, ct + sz, rest);			\
    memcpy(pt, ct, sizeof(text));					\
    pre##_cfbsetiv(&ctx, iv);						\
    pre##_cfbdecrypt(&ctx, pt, pt, rest);				\
    pre##_cfbdecrypt(&ctx, pt + rest, pt + rest, sz);			\
    if (memcmp(pt, text, sizeof(text)) == 0) {				\
      done++;								\
      if (sizeof(text) < 40 || done % 8 == 0)				\
        fputc('.', stdout);						\
      if (done % 480 == 0)						\
        fputs("\n\t", stdout);						\
      fflush(stdout);							\
    } else {								\
      printf("\nError (sz = %lu)\n", (unsigned long)sz);		\
      status = 1;							\
      printf("\tplaintext      = "); hexdump(text, sz);			\
        printf(", "); hexdump(text + sz, rest);				\
        fputc('\n', stdout);						\
      printf("\tciphertext     = "); hexdump(ct, sz);			\
        printf(", "); hexdump(ct + sz, rest);				\
        fputc('\n', stdout);						\
      printf("\trecovered text = "); hexdump(pt, sz);			\
        printf(", "); hexdump(pt + sz, rest);				\
        fputc('\n', stdout);						\
      fputc('\n', stdout);						\
    }									\
    if (sz < 63)							\
      sz++;								\
    else								\
      sz += 9;								\
  }									\
									\
  fputs(status ? " failed\n" : " ok\n", stdout);			\
  return (status);							\
}

#else
#  define CFB_TEST(PRE, pre)
#endif

/*----- That's all, folks -------------------------------------------------*/

#ifdef __cplusplus
  }
#endif

#endif
Commit	Line	Data
79ba130c	1	/* --c--
79ba130c	2	*
b817bfc6	3	* $Id: cfb-def.h,v 1.5 2004/04/08 01:36:15 mdw Exp $
79ba130c	4	*
	5	* Definitions for ciphertext feedback mode
	6	*
	7	* (c) 1999 Straylight/Edgeware
	8	*/
	9
	10	/----- Licensing notice --------------------------------------------------
	11	*
	12	* This file is part of Catacomb.
	13	*
	14	* Catacomb is free software; you can redistribute it and/or modify
	15	* it under the terms of the GNU Library General Public License as
	16	* published by the Free Software Foundation; either version 2 of the
	17	* License, or (at your option) any later version.
	18	*
	19	* Catacomb is distributed in the hope that it will be useful,
	20	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	21	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	22	* GNU Library General Public License for more details.
	23	*
	24	* You should have received a copy of the GNU Library General Public
	25	* License along with Catacomb; if not, write to the Free
	26	* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
	27	* MA 02111-1307, USA.
	28	*/
	29
79ba130c	30	#ifndef CATACOMB_CFB_DEF_H
	31	#define CATACOMB_CFB_DEF_H
	32
	33	#ifdef __cplusplus
	34	extern "C" {
	35	#endif
	36
	37	/----- Header files ------------------------------------------------------/
	38
	39	#include <string.h>
	40
	41	#include <mLib/bits.h>
	42	#include <mLib/sub.h>
	43
426aab6b	44	#ifndef CATACOMB_ARENA_H
	45	# include "arena.h"
	46	#endif
	47
79ba130c	48	#ifndef CATACOMB_BLKC_H
	49	# include "blkc.h"
	50	#endif
	51
	52	#ifndef CATACOMB_GCIPHER_H
	53	# include "gcipher.h"
	54	#endif
	55
	56	#ifndef CATACOMB_PARANOIA_H
	57	# include "paranoia.h"
	58	#endif
	59
426aab6b	60	#ifndef CATACOMB_PARANOIA_H
	61	# include "paranoia.h"
	62	#endif
	63
79ba130c	64	/----- Macros ------------------------------------------------------------/
	65
	66	/* --- @CFB_DEF@ --- *
	67	*
	68	* Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
	69	*
	70	* Use: Creates an implementation for CFB mode.
	71	*/
	72
	73	#define CFB_DEF(PRE, pre) \
	74	\
	75	/* --- @pre_cfbgetiv@ --- * \
	76	* \
	77	* Arguments: @const pre_cfbctx *ctx@ = pointer to CFB context block \
4efe32ba	78	* @void *iv@ = pointer to output data block \
79ba130c	79	* \
	80	* Returns: --- \
	81	* \
	82	* Use: Reads the currently set IV. Reading and setting an IV \
	83	* is not transparent to the cipher. It will add a `step' \
	84	* which must be matched by a similar operation during \
	85	* decryption. \
	86	*/ \
	87	\
	88	void pre##_cfbgetiv(const pre##_cfbctx ctx, void iv) \
	89	{ \
	90	octet *p = iv; \
426aab6b	91	unsigned off = ctx->off; \
426aab6b	92	unsigned rest = PRE##_BLKSZ - off; \
79ba130c	93	memcpy(p, ctx->iv + off, rest); \
	94	memcpy(p + rest, ctx->iv, off); \
	95	} \
	96	\
	97	/* --- @pre_cfbsetiv@ --- * \
	98	* \
	99	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	100	* @cnost void *iv@ = pointer to IV to set \
	101	* \
	102	* Returns: --- \
	103	* \
	104	* Use: Sets the IV to use for subsequent encryption. \
	105	*/ \
	106	\
	107	void pre##_cfbsetiv(pre##_cfbctx ctx, const void iv) \
	108	{ \
426aab6b	109	memcpy(ctx->iv, iv, PRE##_BLKSZ); \
426aab6b	110	ctx->off = PRE##_BLKSZ; \
79ba130c	111	} \
	112	\
	113	/* --- @pre_cfbbdry@ --- * \
	114	* \
	115	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	116	* \
	117	* Returns: --- \
	118	* \
	119	* Use: Inserts a boundary during encryption. Successful \
	120	* decryption must place a similar boundary. \
	121	*/ \
	122	\
	123	void pre##_cfbbdry(pre##_cfbctx *ctx) \
	124	{ \
426aab6b	125	uint32 niv[PRE##_BLKSZ / 4]; \
	126	BLKC_LOAD(PRE, niv, ctx->iv); \
	127	pre##_eblk(&ctx->ctx, niv, niv); \
	128	BLKC_STORE(PRE, ctx->iv, niv); \
	129	ctx->off = PRE##_BLKSZ; \
	130	BURN(niv); \
79ba130c	131	} \
	132	\
	133	/* --- @pre_cfbsetkey@ --- * \
	134	* \
	135	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	136	* @const pre_ctx *k@ = pointer to cipher context \
	137	* \
	138	* Returns: --- \
	139	* \
	140	* Use: Sets the CFB context to use a different cipher key. \
	141	*/ \
	142	\
	143	void pre##_cfbsetkey(pre##_cfbctx ctx, const pre##_ctx k) \
	144	{ \
	145	ctx->ctx = *k; \
426aab6b	146	ctx->off = PRE##_BLKSZ; \
79ba130c	147	} \
	148	\
	149	/* --- @pre_cfbinit@ --- * \
	150	* \
	151	* Arguments: @pre_cfbctx *ctx@ = pointer to cipher context \
	152	* @const void *key@ = pointer to the key buffer \
	153	* @size_t sz@ = size of the key \
	154	* @const void *iv@ = pointer to initialization vector \
	155	* \
	156	* Returns: --- \
	157	* \
	158	* Use: Initializes a CFB context ready for use. You should \
	159	* ensure that the IV chosen is unique: reusing an IV will \
	160	* compromise the security of at least the first block \
	161	* encrypted. This is equivalent to calls to @pre_init@, \
	162	* @pre_cfbsetkey@ and @pre_cfbsetiv@. \
	163	*/ \
	164	\
	165	void pre##_cfbinit(pre##_cfbctx *ctx, \
	166	const void *key, size_t sz, \
	167	const void *iv) \
	168	{ \
4e66da02	169	static const octet zero[PRE##_BLKSZ] = { 0 }; \
79ba130c	170	pre##_init(&ctx->ctx, key, sz); \
	171	pre##_cfbsetiv(ctx, iv ? iv : zero); \
	172	} \
	173	\
	174	/* --- @pre_cfbencrypt@ --- * \
	175	* \
	176	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	177	* @const void *src@ = pointer to source data \
	178	* @void *dest@ = pointer to destination data \
	179	* @size_t sz@ = size of block to be encrypted \
	180	* \
	181	* Returns: --- \
	182	* \
	183	* Use: Encrypts a block with a block cipher in CFB mode. The \
	184	* input block may be arbitrary in size. CFB mode is not \
	185	* sensitive to block boundaries. \
	186	*/ \
	187	\
	188	void pre##_cfbencrypt(pre##_cfbctx *ctx, \
	189	const void src, void dest, \
	190	size_t sz) \
	191	{ \
	192	const octet *s = src; \
	193	octet *d = dest; \
426aab6b	194	unsigned off = ctx->off; \
79ba130c	195	\
	196	/* --- Empty blocks are trivial --- */ \
	197	\
	198	if (!sz) \
	199	return; \
	200	\
	201	/* --- If I can deal with the block from my buffer, do that --- */ \
	202	\
	203	if (sz < PRE##_BLKSZ - off) \
	204	goto small; \
	205	\
	206	/* --- Finish off what's left in my buffer --- */ \
	207	\
	208	while (off < PRE##_BLKSZ) { \
	209	register octet x = *s++; \
	210	*d++ = ctx->iv[off++] ^= x; \
	211	sz--; \
	212	} \
	213	\
	214	/* --- Main encryption loop --- */ \
	215	\
	216	{ \
	217	uint32 iv[PRE##_BLKSZ / 4]; \
	218	BLKC_LOAD(PRE, iv, ctx->iv); \
	219	\
	220	for (;;) { \
	221	pre##_eblk(&ctx->ctx, iv, iv); \
	222	if (sz < PRE##_BLKSZ) \
	223	break; \
	224	BLKC_XLOAD(PRE, iv, s); \
	225	BLKC_STORE(PRE, d, iv); \
	226	s += PRE##_BLKSZ; \
	227	d += PRE##_BLKSZ; \
	228	sz -= PRE##_BLKSZ; \
	229	} \
	230	off = 0; \
	231	BLKC_STORE(PRE, ctx->iv, iv); \
	232	} \
	233	\
	234	/* --- Tidying up the tail end --- */ \
	235	\
	236	if (sz) { \
	237	small: \
	238	do { \
	239	register octet x = *s++; \
	240	*d++ = ctx->iv[off++] ^= x; \
	241	sz--; \
	242	} while (sz); \
	243	} \
	244	\
	245	/* --- Done --- */ \
	246	\
	247	ctx->off = off; \
	248	return; \
	249	} \
	250	\
426aab6b	251	/* --- @pre_cfbdecrypt@ --- * \
79ba130c	252	* \
	253	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	254	* @const void *src@ = pointer to source data \
	255	* @void *dest@ = pointer to destination data \
	256	* @size_t sz@ = size of block to be encrypted \
	257	* \
	258	* Returns: --- \
	259	* \
	260	* Use: Decrypts a block with a block cipher in CFB mode. The \
	261	* input block may be arbitrary in size. CFB mode is not \
	262	* sensitive to block boundaries. \
	263	*/ \
	264	\
	265	void pre##_cfbdecrypt(pre##_cfbctx *ctx, \
	266	const void src, void dest, \
	267	size_t sz) \
	268	{ \
	269	const octet *s = src; \
	270	octet *d = dest; \
426aab6b	271	unsigned off = ctx->off; \
79ba130c	272	\
	273	/* --- Empty blocks are trivial --- */ \
	274	\
	275	if (!sz) \
	276	return; \
	277	\
	278	/* --- If I can deal with the block from my buffer, do that --- */ \
	279	\
	280	if (sz < PRE##_BLKSZ - off) \
	281	goto small; \
	282	\
	283	/* --- Finish off what's left in my buffer --- */ \
	284	\
	285	while (off < PRE##_BLKSZ) { \
	286	register octet x = *s++; \
	287	*d++ = ctx->iv[off] ^ x; \
	288	ctx->iv[off++] = x; \
	289	sz--; \
	290	} \
	291	\
	292	/* --- Main encryption loop --- */ \
	293	\
	294	{ \
	295	uint32 iv[PRE##_BLKSZ / 4]; \
	296	BLKC_LOAD(PRE, iv, ctx->iv); \
	297	\
	298	for (;;) { \
	299	uint32 x[PRE##_BLKSZ / 4]; \
	300	pre##_eblk(&ctx->ctx, iv, iv); \
	301	if (sz < PRE##_BLKSZ) \
	302	break; \
	303	BLKC_LOAD(PRE, x, s); \
	304	BLKC_XSTORE(PRE, d, iv, x); \
	305	BLKC_MOVE(PRE, iv, x); \
	306	s += PRE##_BLKSZ; \
	307	d += PRE##_BLKSZ; \
	308	sz -= PRE##_BLKSZ; \
	309	} \
	310	off = 0; \
	311	BLKC_STORE(PRE, ctx->iv, iv); \
	312	} \
	313	\
	314	/* --- Tidying up the tail end --- */ \
	315	\
	316	if (sz) { \
	317	small: \
	318	do { \
	319	register octet x = *s++; \
	320	*d++ = ctx->iv[off] ^ x; \
	321	ctx->iv[off++] = x; \
	322	sz--; \
	323	} while (sz); \
	324	} \
	325	\
	326	/* --- Done --- */ \
	327	\
	328	ctx->off = off; \
	329	return; \
	330	} \
	331	\
	332	/* --- Generic cipher interface --- */ \
	333	\
	334	static const gcipher_ops gops; \
	335	\
336	typedef struct gctx { \
337	gcipher c; \
338	pre##_cfbctx k; \
339	} gctx; \
340	\
341	static gcipher ginit(const void k, size_t sz) \
342	{ \
426aab6b	343	gctx *g = S_CREATE(gctx); \
79ba130c	344	g->c.ops = &gops; \
	345	pre##_cfbinit(&g->k, k, sz, 0); \
	346	return (&g->c); \
	347	} \
	348	\
	349	static void gencrypt(gcipher c, const void s, void *t, size_t sz) \
	350	{ \
	351	gctx g = (gctx )c; \
	352	pre##_cfbencrypt(&g->k, s, t, sz); \
	353	} \
	354	\
	355	static void gdecrypt(gcipher c, const void s, void *t, size_t sz) \
	356	{ \
	357	gctx g = (gctx )c; \
	358	pre##_cfbdecrypt(&g->k, s, t, sz); \
	359	} \
	360	\
	361	static void gdestroy(gcipher *c) \
	362	{ \
	363	gctx g = (gctx )c; \
426aab6b	364	BURN(*g); \
426aab6b	365	S_DESTROY(g); \
79ba130c	366	} \
	367	\
	368	static void gsetiv(gcipher c, const void iv) \
	369	{ \
	370	gctx g = (gctx )c; \
	371	pre##_cfbsetiv(&g->k, iv); \
	372	} \
	373	\
	374	static void gbdry(gcipher *c) \
	375	{ \
	376	gctx g = (gctx )c; \
	377	pre##_cfbbdry(&g->k); \
	378	} \
	379	\
	380	static const gcipher_ops gops = { \
426aab6b	381	&pre##_cfb, \
426aab6b	382	gencrypt, gdecrypt, gdestroy, gsetiv, gbdry \
79ba130c	383	}; \
	384	\
	385	const gccipher pre##_cfb = { \
426aab6b	386	#pre "-cfb", pre##_keysz, PRE##_BLKSZ, \
79ba130c	387	ginit \
	388	}; \
	389	\
	390	CFB_TEST(PRE, pre)
	391
	392	/----- Test rig ----------------------------------------------------------/
	393
	394	#ifdef TEST_RIG
	395
	396	#include <stdio.h>
	397
	398	#include "daftstory.h"
	399
	400	/* --- @CFB_TEST@ --- *
	401	*
	402	* Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
	403	*
	404	* Use: Standard test rig for CFB functions.
	405	*/
	406
	407	#define CFB_TEST(PRE, pre) \
	408	\
	409	/* --- Initial plaintext for the test --- */ \
	410	\
	411	static const octet text[] = TEXT; \
	412	\
	413	/* --- Key and IV to use --- */ \
	414	\
	415	static const octet key[] = KEY; \
	416	static const octet iv[] = IV; \
	417	\
	418	/* --- Buffers for encryption and decryption output --- */ \
	419	\
	420	static octet ct[sizeof(text)]; \
	421	static octet pt[sizeof(text)]; \
	422	\
	423	static void hexdump(const octet *p, size_t sz) \
	424	{ \
	425	const octet *q = p + sz; \
	426	for (sz = 0; p < q; p++, sz++) { \
	427	printf("%02x", *p); \
	428	if ((sz + 1) % PRE##_BLKSZ == 0) \
	429	putchar(':'); \
	430	} \
	431	} \
	432	\
	433	int main(void) \
	434	{ \
	435	size_t sz = 0, rest; \
	436	pre##_cfbctx ctx; \
	437	int status = 0; \
	438	int done = 0; \
	439	pre##_ctx k; \
	440	\
	441	size_t keysz = PRE##_KEYSZ ? \
	442	PRE##_KEYSZ : strlen((const char *)key); \
	443	\
	444	fputs(#pre "-cfb: ", stdout); \
	445	\
	446	pre##_init(&k, key, keysz); \
	447	pre##_cfbsetkey(&ctx, &k); \
	448	\
	449	while (sz <= sizeof(text)) { \
	450	rest = sizeof(text) - sz; \
451	memcpy(ct, text, sizeof(text)); \
452	pre##_cfbsetiv(&ctx, iv); \
453	pre##_cfbencrypt(&ctx, ct, ct, sz); \
454	pre##_cfbencrypt(&ctx, ct + sz, ct + sz, rest); \
455	memcpy(pt, ct, sizeof(text)); \
456	pre##_cfbsetiv(&ctx, iv); \
457	pre##_cfbdecrypt(&ctx, pt, pt, rest); \
458	pre##_cfbdecrypt(&ctx, pt + rest, pt + rest, sz); \
459	if (memcmp(pt, text, sizeof(text)) == 0) { \
460	done++; \
461	if (sizeof(text) < 40 \|\| done % 8 == 0) \
462	fputc('.', stdout); \
463	if (done % 480 == 0) \
464	fputs("\n\t", stdout); \
465	fflush(stdout); \
466	} else { \
467	printf("\nError (sz = %lu)\n", (unsigned long)sz); \
468	status = 1; \
469	printf("\tplaintext = "); hexdump(text, sz); \
470	printf(", "); hexdump(text + sz, rest); \
471	fputc('\n', stdout); \
472	printf("\tciphertext = "); hexdump(ct, sz); \
473	printf(", "); hexdump(ct + sz, rest); \
474	fputc('\n', stdout); \
475	printf("\trecovered text = "); hexdump(pt, sz); \
476	printf(", "); hexdump(pt + sz, rest); \
477	fputc('\n', stdout); \
478	fputc('\n', stdout); \
479	} \
480	if (sz < 63) \
481	sz++; \
482	else \
483	sz += 9; \
484	} \
485	\
486	fputs(status ? " failed\n" : " ok\n", stdout); \
487	return (status); \
488	}
489
490	#else
491	# define CFB_TEST(PRE, pre)
492	#endif
493
494	/----- That's all, folks -------------------------------------------------/
495
496	#ifdef __cplusplus
497	}
498	#endif
499
500	#endif