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

/* -*-c-*-
 *
 * $Id: cfb-def.h,v 1.2 2000/06/17 10:50:39 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.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: cfb-def.h,v $
 * Revision 1.2  2000/06/17 10:50:39  mdw
 * Use secure arena for memory allocation.  Rearrange setiv slightly.
 *
 * Revision 1.1  1999/12/10 23:16:39  mdw
 * Split mode macros into interface and implementation.
 *
 */

#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 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	*
426aab6b	3	* $Id: cfb-def.h,v 1.2 2000/06/17 10:50:39 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
	30	/----- Revision history --------------------------------------------------
	31	*
	32	* $Log: cfb-def.h,v $
426aab6b	33	* Revision 1.2 2000/06/17 10:50:39 mdw
	34	* Use secure arena for memory allocation. Rearrange setiv slightly.
	35	*
79ba130c	36	* Revision 1.1 1999/12/10 23:16:39 mdw
	37	* Split mode macros into interface and implementation.
	38	*
	39	*/
	40
	41	#ifndef CATACOMB_CFB_DEF_H
	42	#define CATACOMB_CFB_DEF_H
	43
	44	#ifdef __cplusplus
	45	extern "C" {
	46	#endif
	47
	48	/----- Header files ------------------------------------------------------/
	49
	50	#include <string.h>
	51
	52	#include <mLib/bits.h>
	53	#include <mLib/sub.h>
	54
426aab6b	55	#ifndef CATACOMB_ARENA_H
	56	# include "arena.h"
	57	#endif
	58
79ba130c	59	#ifndef CATACOMB_BLKC_H
	60	# include "blkc.h"
	61	#endif
	62
	63	#ifndef CATACOMB_GCIPHER_H
	64	# include "gcipher.h"
	65	#endif
	66
	67	#ifndef CATACOMB_PARANOIA_H
	68	# include "paranoia.h"
	69	#endif
	70
426aab6b	71	#ifndef CATACOMB_PARANOIA_H
	72	# include "paranoia.h"
	73	#endif
	74
79ba130c	75	/----- Macros ------------------------------------------------------------/
	76
	77	/* --- @CFB_DEF@ --- *
	78	*
	79	* Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
	80	*
	81	* Use: Creates an implementation for CFB mode.
	82	*/
	83
	84	#define CFB_DEF(PRE, pre) \
	85	\
	86	/* --- @pre_cfbgetiv@ --- * \
	87	* \
	88	* Arguments: @const pre_cfbctx *ctx@ = pointer to CFB context block \
	89	* @void *iv#@ = pointer to output data block \
	90	* \
	91	* Returns: --- \
	92	* \
	93	* Use: Reads the currently set IV. Reading and setting an IV \
	94	* is not transparent to the cipher. It will add a `step' \
	95	* which must be matched by a similar operation during \
	96	* decryption. \
	97	*/ \
	98	\
	99	void pre##_cfbgetiv(const pre##_cfbctx ctx, void iv) \
	100	{ \
	101	octet *p = iv; \
426aab6b	102	unsigned off = ctx->off; \
426aab6b	103	unsigned rest = PRE##_BLKSZ - off; \
79ba130c	104	memcpy(p, ctx->iv + off, rest); \
	105	memcpy(p + rest, ctx->iv, off); \
	106	} \
	107	\
	108	/* --- @pre_cfbsetiv@ --- * \
	109	* \
	110	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	111	* @cnost void *iv@ = pointer to IV to set \
	112	* \
	113	* Returns: --- \
	114	* \
	115	* Use: Sets the IV to use for subsequent encryption. \
	116	*/ \
	117	\
	118	void pre##_cfbsetiv(pre##_cfbctx ctx, const void iv) \
	119	{ \
426aab6b	120	memcpy(ctx->iv, iv, PRE##_BLKSZ); \
426aab6b	121	ctx->off = PRE##_BLKSZ; \
79ba130c	122	} \
	123	\
	124	/* --- @pre_cfbbdry@ --- * \
	125	* \
	126	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	127	* \
	128	* Returns: --- \
	129	* \
	130	* Use: Inserts a boundary during encryption. Successful \
	131	* decryption must place a similar boundary. \
	132	*/ \
	133	\
	134	void pre##_cfbbdry(pre##_cfbctx *ctx) \
	135	{ \
426aab6b	136	uint32 niv[PRE##_BLKSZ / 4]; \
	137	BLKC_LOAD(PRE, niv, ctx->iv); \
	138	pre##_eblk(&ctx->ctx, niv, niv); \
	139	BLKC_STORE(PRE, ctx->iv, niv); \
	140	ctx->off = PRE##_BLKSZ; \
	141	BURN(niv); \
79ba130c	142	} \
	143	\
	144	/* --- @pre_cfbsetkey@ --- * \
	145	* \
	146	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	147	* @const pre_ctx *k@ = pointer to cipher context \
	148	* \
	149	* Returns: --- \
	150	* \
	151	* Use: Sets the CFB context to use a different cipher key. \
	152	*/ \
	153	\
	154	void pre##_cfbsetkey(pre##_cfbctx ctx, const pre##_ctx k) \
	155	{ \
	156	ctx->ctx = *k; \
426aab6b	157	ctx->off = PRE##_BLKSZ; \
79ba130c	158	} \
	159	\
	160	/* --- @pre_cfbinit@ --- * \
	161	* \
	162	* Arguments: @pre_cfbctx *ctx@ = pointer to cipher context \
	163	* @const void *key@ = pointer to the key buffer \
	164	* @size_t sz@ = size of the key \
	165	* @const void *iv@ = pointer to initialization vector \
	166	* \
	167	* Returns: --- \
	168	* \
	169	* Use: Initializes a CFB context ready for use. You should \
	170	* ensure that the IV chosen is unique: reusing an IV will \
	171	* compromise the security of at least the first block \
	172	* encrypted. This is equivalent to calls to @pre_init@, \
	173	* @pre_cfbsetkey@ and @pre_cfbsetiv@. \
	174	*/ \
	175	\
	176	void pre##_cfbinit(pre##_cfbctx *ctx, \
	177	const void *key, size_t sz, \
	178	const void *iv) \
	179	{ \
	180	static octet zero[PRE##_BLKSZ] = { 0 }; \
	181	pre##_init(&ctx->ctx, key, sz); \
	182	pre##_cfbsetiv(ctx, iv ? iv : zero); \
	183	} \
	184	\
	185	/* --- @pre_cfbencrypt@ --- * \
	186	* \
	187	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	188	* @const void *src@ = pointer to source data \
	189	* @void *dest@ = pointer to destination data \
	190	* @size_t sz@ = size of block to be encrypted \
	191	* \
	192	* Returns: --- \
	193	* \
	194	* Use: Encrypts a block with a block cipher in CFB mode. The \
	195	* input block may be arbitrary in size. CFB mode is not \
	196	* sensitive to block boundaries. \
	197	*/ \
	198	\
	199	void pre##_cfbencrypt(pre##_cfbctx *ctx, \
	200	const void src, void dest, \
	201	size_t sz) \
	202	{ \
	203	const octet *s = src; \
	204	octet *d = dest; \
426aab6b	205	unsigned off = ctx->off; \
79ba130c	206	\
	207	/* --- Empty blocks are trivial --- */ \
	208	\
	209	if (!sz) \
	210	return; \
	211	\
	212	/* --- If I can deal with the block from my buffer, do that --- */ \
	213	\
	214	if (sz < PRE##_BLKSZ - off) \
	215	goto small; \
	216	\
	217	/* --- Finish off what's left in my buffer --- */ \
	218	\
	219	while (off < PRE##_BLKSZ) { \
	220	register octet x = *s++; \
	221	*d++ = ctx->iv[off++] ^= x; \
	222	sz--; \
	223	} \
	224	\
	225	/* --- Main encryption loop --- */ \
	226	\
	227	{ \
	228	uint32 iv[PRE##_BLKSZ / 4]; \
	229	BLKC_LOAD(PRE, iv, ctx->iv); \
	230	\
	231	for (;;) { \
	232	pre##_eblk(&ctx->ctx, iv, iv); \
	233	if (sz < PRE##_BLKSZ) \
	234	break; \
	235	BLKC_XLOAD(PRE, iv, s); \
	236	BLKC_STORE(PRE, d, iv); \
	237	s += PRE##_BLKSZ; \
	238	d += PRE##_BLKSZ; \
	239	sz -= PRE##_BLKSZ; \
	240	} \
	241	off = 0; \
	242	BLKC_STORE(PRE, ctx->iv, iv); \
	243	} \
	244	\
	245	/* --- Tidying up the tail end --- */ \
	246	\
	247	if (sz) { \
	248	small: \
	249	do { \
	250	register octet x = *s++; \
	251	*d++ = ctx->iv[off++] ^= x; \
	252	sz--; \
	253	} while (sz); \
	254	} \
	255	\
	256	/* --- Done --- */ \
	257	\
	258	ctx->off = off; \
	259	return; \
	260	} \
	261	\
426aab6b	262	/* --- @pre_cfbdecrypt@ --- * \
79ba130c	263	* \
	264	* Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
	265	* @const void *src@ = pointer to source data \
	266	* @void *dest@ = pointer to destination data \
	267	* @size_t sz@ = size of block to be encrypted \
	268	* \
	269	* Returns: --- \
	270	* \
	271	* Use: Decrypts a block with a block cipher in CFB mode. The \
	272	* input block may be arbitrary in size. CFB mode is not \
	273	* sensitive to block boundaries. \
	274	*/ \
	275	\
	276	void pre##_cfbdecrypt(pre##_cfbctx *ctx, \
	277	const void src, void dest, \
	278	size_t sz) \
	279	{ \
	280	const octet *s = src; \
	281	octet *d = dest; \
426aab6b	282	unsigned off = ctx->off; \
79ba130c	283	\
	284	/* --- Empty blocks are trivial --- */ \
	285	\
	286	if (!sz) \
	287	return; \
	288	\
	289	/* --- If I can deal with the block from my buffer, do that --- */ \
	290	\
	291	if (sz < PRE##_BLKSZ - off) \
	292	goto small; \
	293	\
	294	/* --- Finish off what's left in my buffer --- */ \
	295	\
	296	while (off < PRE##_BLKSZ) { \
	297	register octet x = *s++; \
	298	*d++ = ctx->iv[off] ^ x; \
	299	ctx->iv[off++] = x; \
	300	sz--; \
	301	} \
	302	\
	303	/* --- Main encryption loop --- */ \
	304	\
	305	{ \
	306	uint32 iv[PRE##_BLKSZ / 4]; \
	307	BLKC_LOAD(PRE, iv, ctx->iv); \
	308	\
	309	for (;;) { \
	310	uint32 x[PRE##_BLKSZ / 4]; \
	311	pre##_eblk(&ctx->ctx, iv, iv); \
	312	if (sz < PRE##_BLKSZ) \
	313	break; \
	314	BLKC_LOAD(PRE, x, s); \
	315	BLKC_XSTORE(PRE, d, iv, x); \
	316	BLKC_MOVE(PRE, iv, x); \
	317	s += PRE##_BLKSZ; \
	318	d += PRE##_BLKSZ; \
	319	sz -= PRE##_BLKSZ; \
	320	} \
	321	off = 0; \
	322	BLKC_STORE(PRE, ctx->iv, iv); \
	323	} \
	324	\
	325	/* --- Tidying up the tail end --- */ \
	326	\
	327	if (sz) { \
	328	small: \
	329	do { \
	330	register octet x = *s++; \
	331	*d++ = ctx->iv[off] ^ x; \
	332	ctx->iv[off++] = x; \
	333	sz--; \
	334	} while (sz); \
	335	} \
	336	\
	337	/* --- Done --- */ \
	338	\
	339	ctx->off = off; \
	340	return; \
	341	} \
	342	\
	343	/* --- Generic cipher interface --- */ \
	344	\
	345	static const gcipher_ops gops; \
	346	\
347	typedef struct gctx { \
348	gcipher c; \
349	pre##_cfbctx k; \
350	} gctx; \
351	\
352	static gcipher ginit(const void k, size_t sz) \
353	{ \
426aab6b	354	gctx *g = S_CREATE(gctx); \
79ba130c	355	g->c.ops = &gops; \
	356	pre##_cfbinit(&g->k, k, sz, 0); \
	357	return (&g->c); \
	358	} \
	359	\
	360	static void gencrypt(gcipher c, const void s, void *t, size_t sz) \
	361	{ \
	362	gctx g = (gctx )c; \
	363	pre##_cfbencrypt(&g->k, s, t, sz); \
	364	} \
	365	\
	366	static void gdecrypt(gcipher c, const void s, void *t, size_t sz) \
	367	{ \
	368	gctx g = (gctx )c; \
	369	pre##_cfbdecrypt(&g->k, s, t, sz); \
	370	} \
	371	\
	372	static void gdestroy(gcipher *c) \
	373	{ \
	374	gctx g = (gctx )c; \
426aab6b	375	BURN(*g); \
426aab6b	376	S_DESTROY(g); \
79ba130c	377	} \
	378	\
	379	static void gsetiv(gcipher c, const void iv) \
	380	{ \
	381	gctx g = (gctx )c; \
	382	pre##_cfbsetiv(&g->k, iv); \
	383	} \
	384	\
	385	static void gbdry(gcipher *c) \
	386	{ \
	387	gctx g = (gctx )c; \
	388	pre##_cfbbdry(&g->k); \
	389	} \
	390	\
	391	static const gcipher_ops gops = { \
426aab6b	392	&pre##_cfb, \
426aab6b	393	gencrypt, gdecrypt, gdestroy, gsetiv, gbdry \
79ba130c	394	}; \
	395	\
	396	const gccipher pre##_cfb = { \
426aab6b	397	#pre "-cfb", pre##_keysz, PRE##_BLKSZ, \
79ba130c	398	ginit \
	399	}; \
	400	\
	401	CFB_TEST(PRE, pre)
	402
	403	/----- Test rig ----------------------------------------------------------/
	404
	405	#ifdef TEST_RIG
	406
	407	#include <stdio.h>
	408
	409	#include "daftstory.h"
	410
	411	/* --- @CFB_TEST@ --- *
	412	*
	413	* Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
	414	*
	415	* Use: Standard test rig for CFB functions.
	416	*/
	417
	418	#define CFB_TEST(PRE, pre) \
	419	\
	420	/* --- Initial plaintext for the test --- */ \
	421	\
	422	static const octet text[] = TEXT; \
	423	\
	424	/* --- Key and IV to use --- */ \
	425	\
	426	static const octet key[] = KEY; \
	427	static const octet iv[] = IV; \
	428	\
	429	/* --- Buffers for encryption and decryption output --- */ \
	430	\
	431	static octet ct[sizeof(text)]; \
	432	static octet pt[sizeof(text)]; \
	433	\
	434	static void hexdump(const octet *p, size_t sz) \
	435	{ \
	436	const octet *q = p + sz; \
	437	for (sz = 0; p < q; p++, sz++) { \
	438	printf("%02x", *p); \
	439	if ((sz + 1) % PRE##_BLKSZ == 0) \
	440	putchar(':'); \
	441	} \
	442	} \
	443	\
	444	int main(void) \
	445	{ \
	446	size_t sz = 0, rest; \
	447	pre##_cfbctx ctx; \
	448	int status = 0; \
	449	int done = 0; \
	450	pre##_ctx k; \
	451	\
	452	size_t keysz = PRE##_KEYSZ ? \
	453	PRE##_KEYSZ : strlen((const char *)key); \
	454	\
	455	fputs(#pre "-cfb: ", stdout); \
	456	\
	457	pre##_init(&k, key, keysz); \
	458	pre##_cfbsetkey(&ctx, &k); \
	459	\
	460	while (sz <= sizeof(text)) { \
	461	rest = sizeof(text) - sz; \
462	memcpy(ct, text, sizeof(text)); \
463	pre##_cfbsetiv(&ctx, iv); \
464	pre##_cfbencrypt(&ctx, ct, ct, sz); \
465	pre##_cfbencrypt(&ctx, ct + sz, ct + sz, rest); \
466	memcpy(pt, ct, sizeof(text)); \
467	pre##_cfbsetiv(&ctx, iv); \
468	pre##_cfbdecrypt(&ctx, pt, pt, rest); \
469	pre##_cfbdecrypt(&ctx, pt + rest, pt + rest, sz); \
470	if (memcmp(pt, text, sizeof(text)) == 0) { \
471	done++; \
472	if (sizeof(text) < 40 \|\| done % 8 == 0) \
473	fputc('.', stdout); \
474	if (done % 480 == 0) \
475	fputs("\n\t", stdout); \
476	fflush(stdout); \
477	} else { \
478	printf("\nError (sz = %lu)\n", (unsigned long)sz); \
479	status = 1; \
480	printf("\tplaintext = "); hexdump(text, sz); \
481	printf(", "); hexdump(text + sz, rest); \
482	fputc('\n', stdout); \
483	printf("\tciphertext = "); hexdump(ct, sz); \
484	printf(", "); hexdump(ct + sz, rest); \
485	fputc('\n', stdout); \
486	printf("\trecovered text = "); hexdump(pt, sz); \
487	printf(", "); hexdump(pt + sz, rest); \
488	fputc('\n', stdout); \
489	fputc('\n', stdout); \
490	} \
491	if (sz < 63) \
492	sz++; \
493	else \
494	sz += 9; \
495	} \
496	\
497	fputs(status ? " failed\n" : " ok\n", stdout); \
498	return (status); \
499	}
500
501	#else
502	# define CFB_TEST(PRE, pre)
503	#endif
504
505	/----- That's all, folks -------------------------------------------------/
506
507	#ifdef __cplusplus
508	}
509	#endif
510
511	#endif