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

/* -*-c-*-
 *
 * 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++;						\
    ctx->iv[off] ^= x;							\
    if (d) *d++ = ctx->iv[off];						\
    off++;								\
    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;								\
      if (s) {								\
	BLKC_XLOAD(PRE, iv, s);						\
	s += PRE##_BLKSZ;						\
      }									\
      if (d) {								\
	BLKC_STORE(PRE, d, iv);						\
	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++;						\
      ctx->iv[off] ^= x;						\
      if (d) *d++ = ctx->iv[off];					\
      off++;								\
      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	*
79ba130c	3	* Definitions for ciphertext feedback mode
	4	*
	5	* (c) 1999 Straylight/Edgeware
	6	*/
	7
45c0fd36	8	/----- Licensing notice --------------------------------------------------
79ba130c	9	*
	10	* This file is part of Catacomb.
	11	*
	12	* Catacomb is free software; you can redistribute it and/or modify
	13	* it under the terms of the GNU Library General Public License as
	14	* published by the Free Software Foundation; either version 2 of the
	15	* License, or (at your option) any later version.
45c0fd36	16	*
79ba130c	17	* Catacomb is distributed in the hope that it will be useful,
	18	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	20	* GNU Library General Public License for more details.
45c0fd36	21	*
79ba130c	22	* You should have received a copy of the GNU Library General Public
	23	* License along with Catacomb; if not, write to the Free
	24	* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
	25	* MA 02111-1307, USA.
	26	*/
	27
79ba130c	28	#ifndef CATACOMB_CFB_DEF_H
	29	#define CATACOMB_CFB_DEF_H
	30
	31	#ifdef __cplusplus
	32	extern "C" {
	33	#endif
	34
	35	/----- Header files ------------------------------------------------------/
	36
	37	#include <string.h>
	38
	39	#include <mLib/bits.h>
	40	#include <mLib/sub.h>
	41
426aab6b	42	#ifndef CATACOMB_ARENA_H
	43	# include "arena.h"
	44	#endif
	45
79ba130c	46	#ifndef CATACOMB_BLKC_H
	47	# include "blkc.h"
	48	#endif
	49
	50	#ifndef CATACOMB_GCIPHER_H
	51	# include "gcipher.h"
	52	#endif
	53
	54	#ifndef CATACOMB_PARANOIA_H
	55	# include "paranoia.h"
	56	#endif
	57
426aab6b	58	#ifndef CATACOMB_PARANOIA_H
	59	# include "paranoia.h"
	60	#endif
	61
79ba130c	62	/----- Macros ------------------------------------------------------------/
	63
	64	/* --- @CFB_DEF@ --- *
	65	*
	66	* Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
	67	*
	68	* Use: Creates an implementation for CFB mode.
	69	*/
	70
	71	#define CFB_DEF(PRE, pre) \
	72	\
	73	/* --- @pre_cfbgetiv@ --- * \
	74	* \
	75	* Arguments: @const pre_cfbctx *ctx@ = pointer to CFB context block \
4efe32ba	76	* @void *iv@ = pointer to output data block \
79ba130c	77	* \
	78	* Returns: --- \
	79	* \
	80	* Use: Reads the currently set IV. Reading and setting an IV \
	81	* is not transparent to the cipher. It will add a `step' \
	82	* which must be matched by a similar operation during \
	83	* decryption. \
	84	*/ \
	85	\
	86	void pre##_cfbgetiv(const pre##_cfbctx ctx, void iv) \
	87	{ \
	88	octet *p = iv; \
426aab6b	89	unsigned off = ctx->off; \
426aab6b	90	unsigned rest = PRE##_BLKSZ - off; \
79ba130c	91	memcpy(p, ctx->iv + off, rest); \
	92	memcpy(p + rest, ctx->iv, off); \
	93	} \
	94	\
	95	/* --- @pre_cfbsetiv@ --- * \
	96	* \
	97	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	98	* @cnost void *iv@ = pointer to IV to set \
	99	* \
	100	* Returns: --- \
	101	* \
	102	* Use: Sets the IV to use for subsequent encryption. \
	103	*/ \
	104	\
	105	void pre##_cfbsetiv(pre##_cfbctx ctx, const void iv) \
	106	{ \
426aab6b	107	memcpy(ctx->iv, iv, PRE##_BLKSZ); \
426aab6b	108	ctx->off = PRE##_BLKSZ; \
79ba130c	109	} \
	110	\
	111	/* --- @pre_cfbbdry@ --- * \
	112	* \
	113	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	114	* \
	115	* Returns: --- \
	116	* \
	117	* Use: Inserts a boundary during encryption. Successful \
	118	* decryption must place a similar boundary. \
	119	*/ \
	120	\
	121	void pre##_cfbbdry(pre##_cfbctx *ctx) \
	122	{ \
426aab6b	123	uint32 niv[PRE##_BLKSZ / 4]; \
	124	BLKC_LOAD(PRE, niv, ctx->iv); \
	125	pre##_eblk(&ctx->ctx, niv, niv); \
	126	BLKC_STORE(PRE, ctx->iv, niv); \
	127	ctx->off = PRE##_BLKSZ; \
	128	BURN(niv); \
79ba130c	129	} \
	130	\
	131	/* --- @pre_cfbsetkey@ --- * \
	132	* \
	133	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	134	* @const pre_ctx *k@ = pointer to cipher context \
	135	* \
	136	* Returns: --- \
	137	* \
	138	* Use: Sets the CFB context to use a different cipher key. \
	139	*/ \
	140	\
	141	void pre##_cfbsetkey(pre##_cfbctx ctx, const pre##_ctx k) \
	142	{ \
	143	ctx->ctx = *k; \
426aab6b	144	ctx->off = PRE##_BLKSZ; \
79ba130c	145	} \
	146	\
	147	/* --- @pre_cfbinit@ --- * \
	148	* \
	149	* Arguments: @pre_cfbctx *ctx@ = pointer to cipher context \
	150	* @const void *key@ = pointer to the key buffer \
	151	* @size_t sz@ = size of the key \
	152	* @const void *iv@ = pointer to initialization vector \
	153	* \
	154	* Returns: --- \
	155	* \
	156	* Use: Initializes a CFB context ready for use. You should \
	157	* ensure that the IV chosen is unique: reusing an IV will \
	158	* compromise the security of at least the first block \
	159	* encrypted. This is equivalent to calls to @pre_init@, \
	160	* @pre_cfbsetkey@ and @pre_cfbsetiv@. \
	161	*/ \
	162	\
	163	void pre##_cfbinit(pre##_cfbctx *ctx, \
	164	const void *key, size_t sz, \
	165	const void *iv) \
	166	{ \
4e66da02	167	static const octet zero[PRE##_BLKSZ] = { 0 }; \
79ba130c	168	pre##_init(&ctx->ctx, key, sz); \
	169	pre##_cfbsetiv(ctx, iv ? iv : zero); \
	170	} \
	171	\
	172	/* --- @pre_cfbencrypt@ --- * \
	173	* \
	174	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	175	* @const void *src@ = pointer to source data \
	176	* @void *dest@ = pointer to destination data \
	177	* @size_t sz@ = size of block to be encrypted \
	178	* \
	179	* Returns: --- \
	180	* \
	181	* Use: Encrypts a block with a block cipher in CFB mode. The \
	182	* input block may be arbitrary in size. CFB mode is not \
	183	* sensitive to block boundaries. \
	184	*/ \
	185	\
	186	void pre##_cfbencrypt(pre##_cfbctx *ctx, \
	187	const void src, void dest, \
	188	size_t sz) \
	189	{ \
	190	const octet *s = src; \
	191	octet *d = dest; \
426aab6b	192	unsigned off = ctx->off; \
79ba130c	193	\
	194	/* --- Empty blocks are trivial --- */ \
	195	\
	196	if (!sz) \
	197	return; \
	198	\
	199	/* --- If I can deal with the block from my buffer, do that --- */ \
	200	\
	201	if (sz < PRE##_BLKSZ - off) \
	202	goto small; \
	203	\
	204	/* --- Finish off what's left in my buffer --- */ \
	205	\
	206	while (off < PRE##_BLKSZ) { \
	207	register octet x = *s++; \
5c3f75ec	208	ctx->iv[off] ^= x; \
	209	if (d) *d++ = ctx->iv[off]; \
	210	off++; \
79ba130c	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; \
5c3f75ec	224	if (s) { \
5c3f75ec	225	BLKC_XLOAD(PRE, iv, s); \
45c0fd36	226	s += PRE##_BLKSZ; \
5c3f75ec	227	} \
5c3f75ec	228	if (d) { \
45c0fd36 MW	229	BLKC_STORE(PRE, d, iv); \
45c0fd36 MW	230	d += PRE##_BLKSZ; \
5c3f75ec	231	} \
79ba130c	232	sz -= PRE##_BLKSZ; \
	233	} \
	234	off = 0; \
	235	BLKC_STORE(PRE, ctx->iv, iv); \
	236	} \
	237	\
	238	/* --- Tidying up the tail end --- */ \
	239	\
	240	if (sz) { \
	241	small: \
	242	do { \
	243	register octet x = *s++; \
5c3f75ec	244	ctx->iv[off] ^= x; \
	245	if (d) *d++ = ctx->iv[off]; \
	246	off++; \
79ba130c	247	sz--; \
	248	} while (sz); \
	249	} \
	250	\
	251	/* --- Done --- */ \
	252	\
	253	ctx->off = off; \
	254	return; \
	255	} \
	256	\
426aab6b	257	/* --- @pre_cfbdecrypt@ --- * \
79ba130c	258	* \
	259	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	260	* @const void *src@ = pointer to source data \
	261	* @void *dest@ = pointer to destination data \
	262	* @size_t sz@ = size of block to be encrypted \
	263	* \
	264	* Returns: --- \
	265	* \
	266	* Use: Decrypts a block with a block cipher in CFB mode. The \
	267	* input block may be arbitrary in size. CFB mode is not \
	268	* sensitive to block boundaries. \
	269	*/ \
	270	\
	271	void pre##_cfbdecrypt(pre##_cfbctx *ctx, \
	272	const void src, void dest, \
	273	size_t sz) \
	274	{ \
	275	const octet *s = src; \
	276	octet *d = dest; \
426aab6b	277	unsigned off = ctx->off; \
79ba130c	278	\
	279	/* --- Empty blocks are trivial --- */ \
	280	\
	281	if (!sz) \
	282	return; \
	283	\
	284	/* --- If I can deal with the block from my buffer, do that --- */ \
	285	\
	286	if (sz < PRE##_BLKSZ - off) \
	287	goto small; \
	288	\
	289	/* --- Finish off what's left in my buffer --- */ \
	290	\
	291	while (off < PRE##_BLKSZ) { \
	292	register octet x = *s++; \
	293	*d++ = ctx->iv[off] ^ x; \
	294	ctx->iv[off++] = x; \
	295	sz--; \
	296	} \
	297	\
	298	/* --- Main encryption loop --- */ \
	299	\
	300	{ \
	301	uint32 iv[PRE##_BLKSZ / 4]; \
	302	BLKC_LOAD(PRE, iv, ctx->iv); \
	303	\
	304	for (;;) { \
	305	uint32 x[PRE##_BLKSZ / 4]; \
	306	pre##_eblk(&ctx->ctx, iv, iv); \
	307	if (sz < PRE##_BLKSZ) \
	308	break; \
	309	BLKC_LOAD(PRE, x, s); \
	310	BLKC_XSTORE(PRE, d, iv, x); \
	311	BLKC_MOVE(PRE, iv, x); \
	312	s += PRE##_BLKSZ; \
	313	d += PRE##_BLKSZ; \
	314	sz -= PRE##_BLKSZ; \
	315	} \
	316	off = 0; \
	317	BLKC_STORE(PRE, ctx->iv, iv); \
	318	} \
	319	\
	320	/* --- Tidying up the tail end --- */ \
	321	\
	322	if (sz) { \
	323	small: \
	324	do { \
	325	register octet x = *s++; \
	326	*d++ = ctx->iv[off] ^ x; \
	327	ctx->iv[off++] = x; \
	328	sz--; \
	329	} while (sz); \
	330	} \
	331	\
	332	/* --- Done --- */ \
	333	\
	334	ctx->off = off; \
	335	return; \
	336	} \
	337	\
	338	/* --- Generic cipher interface --- */ \
	339	\
	340	static const gcipher_ops gops; \
	341	\
342	typedef struct gctx { \
343	gcipher c; \
344	pre##_cfbctx k; \
345	} gctx; \
346	\
347	static gcipher ginit(const void k, size_t sz) \
348	{ \
426aab6b	349	gctx *g = S_CREATE(gctx); \
79ba130c	350	g->c.ops = &gops; \
	351	pre##_cfbinit(&g->k, k, sz, 0); \
	352	return (&g->c); \
	353	} \
	354	\
	355	static void gencrypt(gcipher c, const void s, void *t, size_t sz) \
	356	{ \
	357	gctx g = (gctx )c; \
	358	pre##_cfbencrypt(&g->k, s, t, sz); \
	359	} \
	360	\
	361	static void gdecrypt(gcipher c, const void s, void *t, size_t sz) \
	362	{ \
	363	gctx g = (gctx )c; \
	364	pre##_cfbdecrypt(&g->k, s, t, sz); \
	365	} \
	366	\
	367	static void gdestroy(gcipher *c) \
	368	{ \
	369	gctx g = (gctx )c; \
426aab6b	370	BURN(*g); \
426aab6b	371	S_DESTROY(g); \
79ba130c	372	} \
	373	\
	374	static void gsetiv(gcipher c, const void iv) \
	375	{ \
	376	gctx g = (gctx )c; \
	377	pre##_cfbsetiv(&g->k, iv); \
	378	} \
	379	\
	380	static void gbdry(gcipher *c) \
	381	{ \
	382	gctx g = (gctx )c; \
	383	pre##_cfbbdry(&g->k); \
	384	} \
	385	\
	386	static const gcipher_ops gops = { \
426aab6b	387	&pre##_cfb, \
426aab6b	388	gencrypt, gdecrypt, gdestroy, gsetiv, gbdry \
79ba130c	389	}; \
	390	\
	391	const gccipher pre##_cfb = { \
426aab6b	392	#pre "-cfb", pre##_keysz, PRE##_BLKSZ, \
79ba130c	393	ginit \
	394	}; \
	395	\
	396	CFB_TEST(PRE, pre)
	397
	398	/----- Test rig ----------------------------------------------------------/
	399
	400	#ifdef TEST_RIG
	401
	402	#include <stdio.h>
	403
	404	#include "daftstory.h"
	405
	406	/* --- @CFB_TEST@ --- *
	407	*
	408	* Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
	409	*
	410	* Use: Standard test rig for CFB functions.
	411	*/
	412
	413	#define CFB_TEST(PRE, pre) \
	414	\
	415	/* --- Initial plaintext for the test --- */ \
	416	\
	417	static const octet text[] = TEXT; \
	418	\
	419	/* --- Key and IV to use --- */ \
	420	\
	421	static const octet key[] = KEY; \
	422	static const octet iv[] = IV; \
	423	\
	424	/* --- Buffers for encryption and decryption output --- */ \
	425	\
	426	static octet ct[sizeof(text)]; \
	427	static octet pt[sizeof(text)]; \
	428	\
	429	static void hexdump(const octet *p, size_t sz) \
	430	{ \
	431	const octet *q = p + sz; \
	432	for (sz = 0; p < q; p++, sz++) { \
	433	printf("%02x", *p); \
	434	if ((sz + 1) % PRE##_BLKSZ == 0) \
	435	putchar(':'); \
	436	} \
	437	} \
	438	\
	439	int main(void) \
	440	{ \
	441	size_t sz = 0, rest; \
	442	pre##_cfbctx ctx; \
	443	int status = 0; \
	444	int done = 0; \
	445	pre##_ctx k; \
	446	\
	447	size_t keysz = PRE##_KEYSZ ? \
	448	PRE##_KEYSZ : strlen((const char *)key); \
	449	\
	450	fputs(#pre "-cfb: ", stdout); \
	451	\
	452	pre##_init(&k, key, keysz); \
	453	pre##_cfbsetkey(&ctx, &k); \
	454	\
	455	while (sz <= sizeof(text)) { \
	456	rest = sizeof(text) - sz; \
457	memcpy(ct, text, sizeof(text)); \
458	pre##_cfbsetiv(&ctx, iv); \
459	pre##_cfbencrypt(&ctx, ct, ct, sz); \
460	pre##_cfbencrypt(&ctx, ct + sz, ct + sz, rest); \
461	memcpy(pt, ct, sizeof(text)); \
462	pre##_cfbsetiv(&ctx, iv); \
463	pre##_cfbdecrypt(&ctx, pt, pt, rest); \
464	pre##_cfbdecrypt(&ctx, pt + rest, pt + rest, sz); \
465	if (memcmp(pt, text, sizeof(text)) == 0) { \
466	done++; \
467	if (sizeof(text) < 40 \|\| done % 8 == 0) \
45c0fd36	468	fputc('.', stdout); \
79ba130c	469	if (done % 480 == 0) \
45c0fd36	470	fputs("\n\t", stdout); \
79ba130c	471	fflush(stdout); \
	472	} else { \
	473	printf("\nError (sz = %lu)\n", (unsigned long)sz); \
	474	status = 1; \
	475	printf("\tplaintext = "); hexdump(text, sz); \
45c0fd36 MW	476	printf(", "); hexdump(text + sz, rest); \
45c0fd36 MW	477	fputc('\n', stdout); \
79ba130c	478	printf("\tciphertext = "); hexdump(ct, sz); \
45c0fd36 MW	479	printf(", "); hexdump(ct + sz, rest); \
45c0fd36 MW	480	fputc('\n', stdout); \
79ba130c	481	printf("\trecovered text = "); hexdump(pt, sz); \
45c0fd36 MW	482	printf(", "); hexdump(pt + sz, rest); \
45c0fd36 MW	483	fputc('\n', stdout); \
79ba130c	484	fputc('\n', stdout); \
	485	} \
	486	if (sz < 63) \
	487	sz++; \
	488	else \
	489	sz += 9; \
	490	} \
	491	\
	492	fputs(status ? " failed\n" : " ok\n", stdout); \
	493	return (status); \
	494	}
	495
	496	#else
	497	# define CFB_TEST(PRE, pre)
	498	#endif
	499
	500	/----- That's all, folks -------------------------------------------------/
	501
	502	#ifdef __cplusplus
	503	}
	504	#endif
	505
	506	#endif