Renamed from `rsa-decrypt', since the name was no longer appropriate.

[u/mdw/catacomb] / rc5.c

/* -*-c-*-
 *
 * $Id: rc5.c,v 1.2 2000/06/17 11:56:00 mdw Exp $
 *
 * The RC5-32/12 block cipher
 *
 * (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: rc5.c,v $
 * Revision 1.2  2000/06/17 11:56:00  mdw
 * New key size interface.  Use secure arena for memory allocation.
 *
 * Revision 1.1  1999/09/03 08:41:12  mdw
 * Initial import.
 *
 */

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

#include <assert.h>
#include <stdlib.h>
#include <string.h>

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

#include "arena.h"
#include "blkc.h"
#include "gcipher.h"
#include "rc5.h"

/*----- Global variables --------------------------------------------------*/

const octet rc5_keysz[] = { KSZ_RANGE, RC5_KEYSZ, 1, 255, 1 };

/*----- Internal magical constants ----------------------------------------*/

#define T ((RC5_ROUNDS + 1) * 2)
#define P 0xb7e15163
#define Q 0x9e3779b9

/*----- Main code ---------------------------------------------------------*/

/* --- @rc5_init@ --- *
 *
 * Arguments:	@rc5_ctx *k@ = pointer to a key block
 *		@const void *sbuf@ = pointer to key material
 *		@size_t sz@ = size of the key material
 *
 * Returns:	---
 *
 * Use:		Initializes an RC5 key block.
 */

void rc5_init(rc5_ctx *k, const void *sbuf, size_t sz)
{
  uint32 *l;
  size_t w;

  /* --- Set up the @L@ table --- *
   *
   * This is slightly unfortunately defined.
   */

  KSZ_ASSERT(rc5, sz);

  {
    int i;
    const octet *p = sbuf;

    /* --- Create the buffer --- */

    w = (sz + 3) / 4;
    l = XS_ALLOC(w * sizeof(uint32));

    /* --- Extract the key material --- */

    for (i = 0; sz > 3; i++) {
      l[i] = LOAD32_L(p);
      p += 4;
      sz -= 4;
    }

    /* --- Fix up the tail end --- */

    if (sz) {
      uint32 x = U8(*p++);
      if (sz > 1) x |= (U8(*p++) <<  8);
      if (sz > 2) x |= (U8(*p++) << 16);
      l[i] = x;
    }
  }

  /* --- Initialize the @S@ table --- */

  {
    int i;

    k->s[0] = P;
    for (i = 1; i < T; i++)
      k->s[i] = k->s[i - 1] + Q;
  }

  /* --- Mix in the key --- */

  {
    int m = 3 * (w > T ? w : T);
    int i, j, c;
    uint32 a, b;

    for (c = i = j = a = b = 0; c < m; c++) {
      uint32 x;

      x = k->s[i] + a + b;
      k->s[i] = a = ROL32(x, 3);
      i++; if (i >= T) i = 0;

      x = l[j] + a + b;
      l[j] = b = ROL32(x, a + b);
      j++; if (j >= w) j = 0;
    }
  }

  memset(l, 0, w * sizeof(uint32));
  XS_FREE(l);
}

/* --- @EROUND@, @DROUND@ --- */

#define EROUND(x, y, k) do {						\
  uint32 _x;								\
  _x = x ^ y; x = ROL32(_x, y) + k[0];					\
  _x = y ^ x; y = ROL32(_x, x) + k[1];					\
  k += 2;								\
} while (0)

#define DROUND(x, y, k) do {						\
  uint32 _x;								\
  k -= 2;								\
  _x = y - k[1]; y = ROR32(_x, x) ^ x;					\
  _x = x - k[0]; x = ROR32(_x, y) ^ y;					\
} while (0)

/* --- @EBLK@, @DBLK@ --- */

#define EBLK(a, b, c, d, k) do {					\
  uint32 _l, _r;							\
  const uint32 *_k = (k)->s;						\
									\
  _l = (a) + _k[0];							\
  _r = (b) + _k[1];							\
  _k += 2;								\
									\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  EROUND(_l, _r, _k);							\
  (c) = _l;								\
  (d) = _r;								\
} while (0)

#define DBLK(a, b, c, d, k) do {					\
  uint32 _l, _r;							\
  const uint32 *_k = (k)->s + T;					\
									\
  _l = (a);								\
  _r = (b);								\
									\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
  DROUND(_l, _r, _k);							\
									\
  _k -= 2;								\
  (d) = _r - _k[1];							\
  (c) = _l - _k[0];							\
} while (0)

/* --- @rc5_eblk@, @rc5_dblk@ --- *
 *
 * Arguments:	@const rc5_ctx *k@ = pointer to RC5 context block
 *		@const uint32 s[2]@ = pointer to source block
 *		@uint32 *d[2]@ = pointer to destination block
 *
 * Returns:	---
 *
 * Use:		Low level block encryption and decryption.
 */

void rc5_eblk(const rc5_ctx *k, const uint32 *s, uint32 *d)
{
  EBLK(s[0], s[1], d[0], d[1], k);
}

void rc5_dblk(const rc5_ctx *k, const uint32 *s, uint32 *d)
{
  DBLK(s[0], s[1], d[0], d[1], k);
}

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

BLKC_TEST(RC5, rc5)

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