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

/* -*-c-*-
 *
 * $Id: ofb-def.h,v 1.4 2001/04/03 19:36:36 mdw Exp $
 *
 * Definitions for output 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: ofb-def.h,v $
 * Revision 1.4  2001/04/03 19:36:36  mdw
 * Don't use @va_arg@ as an argument to @STORE32@!
 *
 * Revision 1.3  2000/06/17 11:48:02  mdw
 * Use secure arena for memory allocation.  Rearrange setiv slightly.
 *
 * Revision 1.2  1999/12/13 15:34:01  mdw
 * Add support for seeding from a generic pseudorandom source.
 *
 * Revision 1.1  1999/12/10 23:16:40  mdw
 * Split mode macros into interface and implementation.
 *
 */

#ifndef CATACOMB_OFB_DEF_H
#define CATACOMB_OFB_DEF_H

#ifdef __cplusplus
  extern "C" {
#endif

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

#include <stdarg.h>
#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

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

/* --- @OFB_DEF@ --- *
 *
 * Arguments:	@PRE@, @pre@ = prefixes for the underlying block cipher
 *
 * Use:		Creates definitions for output feedback mode.
 */

#define OFB_DEF(PRE, pre)						\
									\
/* --- @pre_ofbgetiv@ --- *						\
 *									\
 * Arguments:	@const pre_ofbctx *ctx@ = pointer to OFB 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##_ofbgetiv(const pre##_ofbctx *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_ofbsetiv@ --- *						\
 *									\
 * Arguments:	@pre_ofbctx *ctx@ = pointer to OFB context block	\
 *		@cnost void *iv@ = pointer to IV to set			\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Sets the IV to use for subsequent encryption.		\
 */									\
									\
void pre##_ofbsetiv(pre##_ofbctx *ctx, const void *iv)			\
{									\
  memcpy(ctx->iv, iv, PRE##_BLKSZ);					\
  ctx->off = PRE##_BLKSZ;						\
}									\
									\
/* --- @pre_ofbbdry@ --- *						\
 *									\
 * Arguments:	@pre_ofbctx *ctx@ = pointer to OFB context block	\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Inserts a boundary during encryption.  Successful	\
 *		decryption must place a similar boundary.		\
 */									\
									\
void pre##_ofbbdry(pre##_ofbctx *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_ofbsetkey@ --- *						\
 *									\
 * Arguments:	@pre_ofbctx *ctx@ = pointer to OFB context block	\
 *		@const pre_ctx *k@ = pointer to cipher context		\
 *									\
 * Returns:	---							\
 *									\
 * Use:		Sets the OFB context to use a different cipher key.	\
 */									\
									\
void pre##_ofbsetkey(pre##_ofbctx *ctx, const pre##_ctx *k)		\
{									\
  ctx->ctx = *k;							\
}									\
									\
/* --- @pre_ofbinit@ --- *						\
 *									\
 * Arguments:	@pre_ofbctx *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 OFB context ready for use.  You should	\
 *		ensure that the IV chosen is unique: reusing an IV will	\
 *		compromise the security of the entire plaintext.  This	\
 *		is equivalent to calls to @pre_init@, @pre_ofbsetkey@	\
 *		and @pre_ofbsetiv@.					\
 */									\
									\
void pre##_ofbinit(pre##_ofbctx *ctx,					\
		     const void *key, size_t sz,			\
		     const void *iv)					\
{									\
  static octet zero[PRE##_BLKSZ] = { 0 };				\
  pre##_init(&ctx->ctx, key, sz);					\
  pre##_ofbsetiv(ctx, iv ? iv : zero);					\
}									\
									\
/* --- @pre_ofbencrypt@ --- *						\
 *									\
 * Arguments:	@pre_ofbctx *ctx@ = pointer to OFB 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 or decrypts a block with a block cipher in OFB	\
 *		mode: encryption and decryption are the same in OFB.	\
 *		The destination may be null to just churn the feedback	\
 *		round for a bit.  The source may be null to use the	\
 *		cipher as a random data generator.			\
 */									\
									\
void pre##_ofbencrypt(pre##_ofbctx *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 --- */			\
									\
  if (!d)								\
    sz -= PRE##_BLKSZ - off;						\
  else {								\
    while (off < PRE##_BLKSZ) {						\
      register octet x = s ? *s++ : 0;					\
      *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;								\
      if (d) {								\
	if (!s)								\
	  BLKC_STORE(PRE, d, iv);					\
	else {								\
	  uint32 x[PRE##_BLKSZ / 4];					\
	  BLKC_LOAD(PRE, x, s);						\
	  BLKC_XSTORE(PRE, d, iv, x);					\
	  s += PRE##_BLKSZ;						\
	}								\
	d += PRE##_BLKSZ;						\
      }									\
      sz -= PRE##_BLKSZ;						\
    }									\
									\
    BLKC_STORE(PRE, ctx->iv, iv);					\
    off = 0;								\
  }									\
									\
  /* --- Tidying up the tail end --- */					\
									\
  if (sz) {								\
  small:								\
    if (!d)								\
      off += sz;							\
    else do {								\
      register octet x = s ? *s++ : 0;					\
      *d++ = 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##_ofbctx k;							\
} gctx;									\
									\
static gcipher *ginit(const void *k, size_t sz)				\
{									\
  gctx *g = S_CREATE(gctx);						\
  g->c.ops = &gops;							\
  pre##_ofbinit(&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##_ofbencrypt(&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##_ofbsetiv(&g->k, iv);						\
}									\
									\
static void gbdry(gcipher *c)						\
{									\
  gctx *g = (gctx *)c;							\
  pre##_ofbbdry(&g->k);							\
}									\
									\
static const gcipher_ops gops = {					\
  &pre##_ofb,								\
  gencrypt, gencrypt, gdestroy, gsetiv, gbdry				\
};									\
									\
const gccipher pre##_ofb = {						\
  #pre "-ofb", pre##_keysz, PRE##_BLKSZ,				\
  ginit									\
};									\
									\
/* --- Generic random number generator interface --- */			\
									\
typedef struct grctx {							\
  grand r;								\
  pre##_ofbctx k;							\
} grctx;								\
									\
static void grdestroy(grand *r)						\
{									\
  grctx *g = (grctx *)r;						\
  BURN(*g);								\
  S_DESTROY(g);								\
}									\
									\
static int grmisc(grand *r, unsigned op, ...)				\
{									\
  grctx *g = (grctx *)r;						\
  va_list ap;								\
  int rc = 0;								\
  uint32 i;								\
  octet buf[PRE##_BLKSZ];						\
  va_start(ap, op);							\
									\
  switch (op) {								\
    case GRAND_CHECK:							\
      switch (va_arg(ap, unsigned)) {					\
	case GRAND_CHECK:						\
	case GRAND_SEEDINT:						\
	case GRAND_SEEDUINT32:						\
	case GRAND_SEEDBLOCK:						\
	case GRAND_SEEDRAND:						\
	  rc = 1;							\
	  break;							\
	default:							\
	  rc = 0;							\
	  break;							\
      }									\
      break;								\
    case GRAND_SEEDINT:							\
      memset(buf, 0, sizeof(buf));					\
      i = va_arg(ap, unsigned);						\
      STORE32(buf, i);							\
      pre##_ofbsetiv(&g->k, buf);					\
      break;								\
    case GRAND_SEEDUINT32:						\
      memset(buf, 0, sizeof(buf));					\
      i = va_arg(ap, uint32);						\
      STORE32(buf, i);							\
      pre##_ofbsetiv(&g->k, buf);					\
      break;								\
    case GRAND_SEEDBLOCK: {						\
      const void *p = va_arg(ap, const void *);				\
      size_t sz = va_arg(ap, size_t);					\
      if (sz < sizeof(buf)) {						\
	memset(buf, 0, sizeof(buf));					\
	memcpy(buf, p, sz);						\
	p = buf;							\
      }									\
      pre##_ofbsetiv(&g->k, p);						\
    } break;								\
    case GRAND_SEEDRAND: {						\
      grand *rr = va_arg(ap, grand *);					\
      rr->ops->fill(rr, buf, sizeof(buf));				\
      pre##_ofbsetiv(&g->k, buf);					\
    } break;								\
    default:								\
      GRAND_BADOP;							\
      break;								\
  }									\
									\
  va_end(ap);								\
  return (rc);								\
}									\
									\
static octet grbyte(grand *r)						\
{									\
  grctx *g = (grctx *)r;						\
  octet o;								\
  pre##_ofbencrypt(&g->k, 0, &o, 1);					\
  return (o);								\
}									\
									\
static uint32 grword(grand *r)						\
{									\
  grctx *g = (grctx *)r;						\
  octet b[4];								\
  pre##_ofbencrypt(&g->k, 0, b, sizeof(b));				\
  return (LOAD32(b));							\
}									\
									\
static void grfill(grand *r, void *p, size_t sz)			\
{									\
  grctx *g = (grctx *)r;						\
  pre##_ofbencrypt(&g->k, 0, p, sz);					\
}									\
									\
static const grand_ops grops = {					\
  #pre "-ofb",								\
  GRAND_CRYPTO, 0,							\
  grmisc, grdestroy,							\
  grword, grbyte, grword, grand_range, grfill				\
};									\
									\
/* --- @pre_ofbrand@ --- *						\
 *									\
 * Arguments:	@const void *k@ = pointer to key material		\
 *		@size_t sz@ = size of key material			\
 *									\
 * Returns:	Pointer to generic random number generator interface.	\
 *									\
 * Use:		Creates a random number interface wrapper around an	\
 *		OFB-mode block cipher.					\
 */									\
									\
grand *pre##_ofbrand(const void *k, size_t sz)				\
{									\
  grctx *g = S_CREATE(grctx);						\
  g->r.ops = &grops;							\
  pre##_ofbinit(&g->k, k, sz, 0);					\
  return (&g->r);							\
}									\
									\
OFB_TEST(PRE, pre)

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

#ifdef TEST_RIG

#include <stdio.h>

#include "daftstory.h"

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

#define OFB_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##_ofbctx ctx;							\
  int status = 0;							\
  int done = 0;								\
  pre##_ctx k;								\
									\
  size_t keysz = PRE##_KEYSZ ?						\
    PRE##_KEYSZ : strlen((const char *)key);				\
									\
  fputs(#pre "-ofb: ", stdout);						\
									\
  pre##_init(&k, key, keysz);						\
  pre##_ofbsetkey(&ctx, &k);						\
									\
  while (sz <= sizeof(text)) {						\
    rest = sizeof(text) - sz;						\
    memcpy(ct, text, sizeof(text));					\
    pre##_ofbsetiv(&ctx, iv);						\
    pre##_ofbencrypt(&ctx, ct, ct, sz);					\
    pre##_ofbencrypt(&ctx, ct + sz, ct + sz, rest);			\
    memcpy(pt, ct, sizeof(text));					\
    pre##_ofbsetiv(&ctx, iv);						\
    pre##_ofbencrypt(&ctx, pt, pt, rest);				\
    pre##_ofbencrypt(&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 OFB_TEST(PRE, pre)
#endif

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

#ifdef __cplusplus
  }
#endif

#endif
Commit	Line	Data
79ba130c	1	/* --c--
79ba130c	2	*
360c232e	3	* $Id: ofb-def.h,v 1.4 2001/04/03 19:36:36 mdw Exp $
79ba130c	4	*
	5	* Definitions for output 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: ofb-def.h,v $
360c232e	33	* Revision 1.4 2001/04/03 19:36:36 mdw
	34	* Don't use @va_arg@ as an argument to @STORE32@!
	35	*
2af20fa2	36	* Revision 1.3 2000/06/17 11:48:02 mdw
	37	* Use secure arena for memory allocation. Rearrange setiv slightly.
	38	*
4ab1268f	39	* Revision 1.2 1999/12/13 15:34:01 mdw
	40	* Add support for seeding from a generic pseudorandom source.
	41	*
79ba130c	42	* Revision 1.1 1999/12/10 23:16:40 mdw
	43	* Split mode macros into interface and implementation.
	44	*
	45	*/
	46
	47	#ifndef CATACOMB_OFB_DEF_H
	48	#define CATACOMB_OFB_DEF_H
	49
	50	#ifdef __cplusplus
	51	extern "C" {
	52	#endif
	53
	54	/----- Header files ------------------------------------------------------/
	55
	56	#include <stdarg.h>
	57	#include <string.h>
	58
	59	#include <mLib/bits.h>
	60	#include <mLib/sub.h>
	61
2af20fa2	62	#ifndef CATACOMB_ARENA_H
	63	# include "arena.h"
	64	#endif
	65
79ba130c	66	#ifndef CATACOMB_BLKC_H
	67	# include "blkc.h"
	68	#endif
	69
	70	#ifndef CATACOMB_GCIPHER_H
	71	# include "gcipher.h"
	72	#endif
	73
	74	#ifndef CATACOMB_PARANOIA_H
	75	# include "paranoia.h"
	76	#endif
	77
	78	/----- Macros ------------------------------------------------------------/
	79
	80	/* --- @OFB_DEF@ --- *
	81	*
	82	* Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
	83	*
	84	* Use: Creates definitions for output feedback mode.
	85	*/
	86
	87	#define OFB_DEF(PRE, pre) \
	88	\
	89	/* --- @pre_ofbgetiv@ --- * \
	90	* \
	91	* Arguments: @const pre_ofbctx *ctx@ = pointer to OFB context block \
	92	* @void *iv#@ = pointer to output data block \
	93	* \
	94	* Returns: --- \
	95	* \
	96	* Use: Reads the currently set IV. Reading and setting an IV \
	97	* is not transparent to the cipher. It will add a `step' \
	98	* which must be matched by a similar operation during \
	99	* decryption. \
	100	*/ \
	101	\
	102	void pre##_ofbgetiv(const pre##_ofbctx ctx, void iv) \
	103	{ \
	104	octet *p = iv; \
2af20fa2	105	unsigned off = ctx->off; \
2af20fa2	106	unsigned rest = PRE##_BLKSZ - off; \
79ba130c	107	memcpy(p, ctx->iv + off, rest); \
	108	memcpy(p + rest, ctx->iv, off); \
	109	} \
	110	\
	111	/* --- @pre_ofbsetiv@ --- * \
	112	* \
	113	* Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \
	114	* @cnost void *iv@ = pointer to IV to set \
	115	* \
	116	* Returns: --- \
	117	* \
	118	* Use: Sets the IV to use for subsequent encryption. \
	119	*/ \
	120	\
	121	void pre##_ofbsetiv(pre##_ofbctx ctx, const void iv) \
	122	{ \
2af20fa2	123	memcpy(ctx->iv, iv, PRE##_BLKSZ); \
2af20fa2	124	ctx->off = PRE##_BLKSZ; \
79ba130c	125	} \
	126	\
	127	/* --- @pre_ofbbdry@ --- * \
	128	* \
	129	* Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \
	130	* \
	131	* Returns: --- \
	132	* \
	133	* Use: Inserts a boundary during encryption. Successful \
	134	* decryption must place a similar boundary. \
	135	*/ \
	136	\
	137	void pre##_ofbbdry(pre##_ofbctx *ctx) \
	138	{ \
2af20fa2	139	uint32 niv[PRE##_BLKSZ / 4]; \
	140	BLKC_LOAD(PRE, niv, ctx->iv); \
	141	pre##_eblk(&ctx->ctx, niv, niv); \
	142	BLKC_STORE(PRE, ctx->iv, niv); \
	143	ctx->off = PRE##_BLKSZ; \
	144	BURN(niv); \
79ba130c	145	} \
	146	\
	147	/* --- @pre_ofbsetkey@ --- * \
	148	* \
	149	* Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \
	150	* @const pre_ctx *k@ = pointer to cipher context \
	151	* \
	152	* Returns: --- \
	153	* \
	154	* Use: Sets the OFB context to use a different cipher key. \
	155	*/ \
	156	\
	157	void pre##_ofbsetkey(pre##_ofbctx ctx, const pre##_ctx k) \
	158	{ \
	159	ctx->ctx = *k; \
	160	} \
	161	\
	162	/* --- @pre_ofbinit@ --- * \
	163	* \
	164	* Arguments: @pre_ofbctx *ctx@ = pointer to cipher context \
	165	* @const void *key@ = pointer to the key buffer \
	166	* @size_t sz@ = size of the key \
	167	* @const void *iv@ = pointer to initialization vector \
	168	* \
	169	* Returns: --- \
	170	* \
	171	* Use: Initializes a OFB context ready for use. You should \
	172	* ensure that the IV chosen is unique: reusing an IV will \
	173	* compromise the security of the entire plaintext. This \
	174	* is equivalent to calls to @pre_init@, @pre_ofbsetkey@ \
	175	* and @pre_ofbsetiv@. \
	176	*/ \
	177	\
	178	void pre##_ofbinit(pre##_ofbctx *ctx, \
	179	const void *key, size_t sz, \
	180	const void *iv) \
	181	{ \
	182	static octet zero[PRE##_BLKSZ] = { 0 }; \
	183	pre##_init(&ctx->ctx, key, sz); \
	184	pre##_ofbsetiv(ctx, iv ? iv : zero); \
	185	} \
	186	\
	187	/* --- @pre_ofbencrypt@ --- * \
	188	* \
	189	* Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \
	190	* @const void *src@ = pointer to source data \
	191	* @void *dest@ = pointer to destination data \
	192	* @size_t sz@ = size of block to be encrypted \
	193	* \
	194	* Returns: --- \
	195	* \
	196	* Use: Encrypts or decrypts a block with a block cipher in OFB \
	197	* mode: encryption and decryption are the same in OFB. \
	198	* The destination may be null to just churn the feedback \
	199	* round for a bit. The source may be null to use the \
	200	* cipher as a random data generator. \
	201	*/ \
	202	\
	203	void pre##_ofbencrypt(pre##_ofbctx *ctx, \
	204	const void src, void dest, \
	205	size_t sz) \
	206	{ \
	207	const octet *s = src; \
	208	octet *d = dest; \
2af20fa2	209	unsigned off = ctx->off; \
79ba130c	210	\
	211	/* --- Empty blocks are trivial --- */ \
	212	\
	213	if (!sz) \
	214	return; \
	215	\
	216	/* --- If I can deal with the block from my buffer, do that --- */ \
	217	\
	218	if (sz < PRE##_BLKSZ - off) \
	219	goto small; \
	220	\
	221	/* --- Finish off what's left in my buffer --- */ \
	222	\
	223	if (!d) \
2af20fa2	224	sz -= PRE##_BLKSZ - off; \
79ba130c	225	else { \
	226	while (off < PRE##_BLKSZ) { \
	227	register octet x = s ? *s++ : 0; \
	228	*d++ = ctx->iv[off++] ^ x; \
	229	sz--; \
	230	} \
	231	} \
	232	\
	233	/* --- Main encryption loop --- */ \
	234	\
	235	{ \
	236	uint32 iv[PRE##_BLKSZ / 4]; \
	237	BLKC_LOAD(PRE, iv, ctx->iv); \
	238	\
	239	for (;;) { \
	240	pre##_eblk(&ctx->ctx, iv, iv); \
	241	if (sz < PRE##_BLKSZ) \
	242	break; \
	243	if (d) { \
	244	if (!s) \
	245	BLKC_STORE(PRE, d, iv); \
	246	else { \
	247	uint32 x[PRE##_BLKSZ / 4]; \
	248	BLKC_LOAD(PRE, x, s); \
	249	BLKC_XSTORE(PRE, d, iv, x); \
	250	s += PRE##_BLKSZ; \
	251	} \
	252	d += PRE##_BLKSZ; \
	253	} \
	254	sz -= PRE##_BLKSZ; \
	255	} \
	256	\
	257	BLKC_STORE(PRE, ctx->iv, iv); \
	258	off = 0; \
	259	} \
	260	\
	261	/* --- Tidying up the tail end --- */ \
	262	\
	263	if (sz) { \
	264	small: \
	265	if (!d) \
	266	off += sz; \
	267	else do { \
	268	register octet x = s ? *s++ : 0; \
	269	*d++ = ctx->iv[off++] ^ x; \
	270	sz--; \
	271	} while (sz); \
	272	} \
	273	\
	274	/* --- Done --- */ \
	275	\
	276	ctx->off = off; \
	277	return; \
	278	} \
	279	\
	280	/* --- Generic cipher interface --- */ \
	281	\
	282	static const gcipher_ops gops; \
	283	\
	284	typedef struct gctx { \
	285	gcipher c; \
	286	pre##_ofbctx k; \
	287	} gctx; \
	288	\
289	static gcipher ginit(const void k, size_t sz) \
290	{ \
2af20fa2	291	gctx *g = S_CREATE(gctx); \
79ba130c	292	g->c.ops = &gops; \
	293	pre##_ofbinit(&g->k, k, sz, 0); \
	294	return (&g->c); \
	295	} \
	296	\
	297	static void gencrypt(gcipher c, const void s, void *t, size_t sz) \
	298	{ \
	299	gctx g = (gctx )c; \
	300	pre##_ofbencrypt(&g->k, s, t, sz); \
	301	} \
	302	\
	303	static void gdestroy(gcipher *c) \
	304	{ \
	305	gctx g = (gctx )c; \
2af20fa2	306	BURN(*g); \
2af20fa2	307	S_DESTROY(g); \
79ba130c	308	} \
	309	\
	310	static void gsetiv(gcipher c, const void iv) \
	311	{ \
	312	gctx g = (gctx )c; \
	313	pre##_ofbsetiv(&g->k, iv); \
	314	} \
	315	\
	316	static void gbdry(gcipher *c) \
	317	{ \
	318	gctx g = (gctx )c; \
	319	pre##_ofbbdry(&g->k); \
	320	} \
	321	\
	322	static const gcipher_ops gops = { \
2af20fa2	323	&pre##_ofb, \
79ba130c	324	gencrypt, gencrypt, gdestroy, gsetiv, gbdry \
	325	}; \
	326	\
	327	const gccipher pre##_ofb = { \
2af20fa2	328	#pre "-ofb", pre##_keysz, PRE##_BLKSZ, \
79ba130c	329	ginit \
	330	}; \
	331	\
	332	/* --- Generic random number generator interface --- */ \
	333	\
	334	typedef struct grctx { \
	335	grand r; \
	336	pre##_ofbctx k; \
	337	} grctx; \
	338	\
	339	static void grdestroy(grand *r) \
	340	{ \
	341	grctx g = (grctx )r; \
2af20fa2	342	BURN(*g); \
2af20fa2	343	S_DESTROY(g); \
79ba130c	344	} \
	345	\
	346	static int grmisc(grand *r, unsigned op, ...) \
	347	{ \
	348	grctx g = (grctx )r; \
	349	va_list ap; \
	350	int rc = 0; \
360c232e	351	uint32 i; \
79ba130c	352	octet buf[PRE##_BLKSZ]; \
	353	va_start(ap, op); \
	354	\
	355	switch (op) { \
	356	case GRAND_CHECK: \
	357	switch (va_arg(ap, unsigned)) { \
	358	case GRAND_CHECK: \
	359	case GRAND_SEEDINT: \
	360	case GRAND_SEEDUINT32: \
	361	case GRAND_SEEDBLOCK: \
4ab1268f	362	case GRAND_SEEDRAND: \
79ba130c	363	rc = 1; \
	364	break; \
	365	default: \
	366	rc = 0; \
	367	break; \
	368	} \
	369	break; \
	370	case GRAND_SEEDINT: \
	371	memset(buf, 0, sizeof(buf)); \
360c232e	372	i = va_arg(ap, unsigned); \
360c232e	373	STORE32(buf, i); \
79ba130c	374	pre##_ofbsetiv(&g->k, buf); \
	375	break; \
	376	case GRAND_SEEDUINT32: \
	377	memset(buf, 0, sizeof(buf)); \
360c232e	378	i = va_arg(ap, uint32); \
360c232e	379	STORE32(buf, i); \
79ba130c	380	pre##_ofbsetiv(&g->k, buf); \
	381	break; \
	382	case GRAND_SEEDBLOCK: { \
	383	const void p = va_arg(ap, const void ); \
	384	size_t sz = va_arg(ap, size_t); \
	385	if (sz < sizeof(buf)) { \
	386	memset(buf, 0, sizeof(buf)); \
	387	memcpy(buf, p, sz); \
	388	p = buf; \
	389	} \
	390	pre##_ofbsetiv(&g->k, p); \
	391	} break; \
4ab1268f	392	case GRAND_SEEDRAND: { \
	393	grand rr = va_arg(ap, grand ); \
	394	rr->ops->fill(rr, buf, sizeof(buf)); \
	395	pre##_ofbsetiv(&g->k, buf); \
	396	} break; \
	397	default: \
	398	GRAND_BADOP; \
	399	break; \
79ba130c	400	} \
	401	\
	402	va_end(ap); \
	403	return (rc); \
	404	} \
	405	\
	406	static octet grbyte(grand *r) \
	407	{ \
	408	grctx g = (grctx )r; \
	409	octet o; \
	410	pre##_ofbencrypt(&g->k, 0, &o, 1); \
	411	return (o); \
	412	} \
	413	\
	414	static uint32 grword(grand *r) \
	415	{ \
	416	grctx g = (grctx )r; \
	417	octet b[4]; \
	418	pre##_ofbencrypt(&g->k, 0, b, sizeof(b)); \
	419	return (LOAD32(b)); \
	420	} \
	421	\
	422	static void grfill(grand r, void p, size_t sz) \
	423	{ \
	424	grctx g = (grctx )r; \
	425	pre##_ofbencrypt(&g->k, 0, p, sz); \
	426	} \
	427	\
	428	static const grand_ops grops = { \
	429	#pre "-ofb", \
2af20fa2	430	GRAND_CRYPTO, 0, \
79ba130c	431	grmisc, grdestroy, \
	432	grword, grbyte, grword, grand_range, grfill \
	433	}; \
	434	\
	435	/* --- @pre_ofbrand@ --- * \
	436	* \
	437	* Arguments: @const void *k@ = pointer to key material \
	438	* @size_t sz@ = size of key material \
	439	* \
	440	* Returns: Pointer to generic random number generator interface. \
	441	* \
	442	* Use: Creates a random number interface wrapper around an \
	443	* OFB-mode block cipher. \
	444	*/ \
	445	\
	446	grand pre##_ofbrand(const void k, size_t sz) \
	447	{ \
2af20fa2	448	grctx *g = S_CREATE(grctx); \
79ba130c	449	g->r.ops = &grops; \
	450	pre##_ofbinit(&g->k, k, sz, 0); \
	451	return (&g->r); \
	452	} \
	453	\
	454	OFB_TEST(PRE, pre)
	455
	456	/----- Test rig ----------------------------------------------------------/
	457
	458	#ifdef TEST_RIG
	459
	460	#include <stdio.h>
	461
	462	#include "daftstory.h"
	463
	464	/* --- @OFB_TEST@ --- *
	465	*
	466	* Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
	467	*
	468	* Use: Standard test rig for OFB functions.
	469	*/
	470
	471	#define OFB_TEST(PRE, pre) \
	472	\
	473	/* --- Initial plaintext for the test --- */ \
	474	\
	475	static const octet text[] = TEXT; \
	476	\
	477	/* --- Key and IV to use --- */ \
	478	\
	479	static const octet key[] = KEY; \
	480	static const octet iv[] = IV; \
	481	\
	482	/* --- Buffers for encryption and decryption output --- */ \
	483	\
	484	static octet ct[sizeof(text)]; \
	485	static octet pt[sizeof(text)]; \
	486	\
	487	static void hexdump(const octet *p, size_t sz) \
	488	{ \
	489	const octet *q = p + sz; \
	490	for (sz = 0; p < q; p++, sz++) { \
	491	printf("%02x", *p); \
	492	if ((sz + 1) % PRE##_BLKSZ == 0) \
	493	putchar(':'); \
	494	} \
	495	} \
	496	\
	497	int main(void) \
	498	{ \
	499	size_t sz = 0, rest; \
	500	pre##_ofbctx ctx; \
	501	int status = 0; \
	502	int done = 0; \
	503	pre##_ctx k; \
	504	\
	505	size_t keysz = PRE##_KEYSZ ? \
	506	PRE##_KEYSZ : strlen((const char *)key); \
	507	\
	508	fputs(#pre "-ofb: ", stdout); \
	509	\
	510	pre##_init(&k, key, keysz); \
	511	pre##_ofbsetkey(&ctx, &k); \
	512	\
513	while (sz <= sizeof(text)) { \
514	rest = sizeof(text) - sz; \
515	memcpy(ct, text, sizeof(text)); \
516	pre##_ofbsetiv(&ctx, iv); \
517	pre##_ofbencrypt(&ctx, ct, ct, sz); \
518	pre##_ofbencrypt(&ctx, ct + sz, ct + sz, rest); \
519	memcpy(pt, ct, sizeof(text)); \
520	pre##_ofbsetiv(&ctx, iv); \
521	pre##_ofbencrypt(&ctx, pt, pt, rest); \
522	pre##_ofbencrypt(&ctx, pt + rest, pt + rest, sz); \
523	if (memcmp(pt, text, sizeof(text)) == 0) { \
524	done++; \
525	if (sizeof(text) < 40 \|\| done % 8 == 0) \
526	fputc('.', stdout); \
527	if (done % 480 == 0) \
528	fputs("\n\t", stdout); \
529	fflush(stdout); \
530	} else { \
531	printf("\nError (sz = %lu)\n", (unsigned long)sz); \
532	status = 1; \
533	printf("\tplaintext = "); hexdump(text, sz); \
534	printf(", "); hexdump(text + sz, rest); \
535	fputc('\n', stdout); \
536	printf("\tciphertext = "); hexdump(ct, sz); \
537	printf(", "); hexdump(ct + sz, rest); \
538	fputc('\n', stdout); \
539	printf("\trecovered text = "); hexdump(pt, sz); \
540	printf(", "); hexdump(pt + sz, rest); \
541	fputc('\n', stdout); \
542	fputc('\n', stdout); \
543	} \
544	if (sz < 63) \
545	sz++; \
546	else \
547	sz += 9; \
548	} \
549	\
550	fputs(status ? " failed\n" : " ok\n", stdout); \
551	return (status); \
552	}
553
554	#else
555	# define OFB_TEST(PRE, pre)
556	#endif
557
558	/----- That's all, folks -------------------------------------------------/
559
560	#ifdef __cplusplus
561	}
562	#endif
563
564	#endif