md2.c 4.21 KB
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/* md2.h
 *
 * The MD2 hash function. XXX What RFC, if any?
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2003 Niels Mller
 *  
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 * 
 * The nettle library 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 Lesser General Public
 * License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/* This code originates from the Python Cryptography Toolkit, version 1.0.1.
   Further hacked by Andreas Sigfridsson and Niels Mller */
#if HAVE_CONFIG_H
# include "config.h"
#endif

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

#include "md2.h"

#include "macros.h"

static const uint8_t
S[256] = {
  41, 46, 67, 201, 162, 216, 124, 1, 61, 54, 84, 161, 236, 240, 6,
  19, 98, 167, 5, 243, 192, 199, 115, 140, 152, 147, 43, 217, 188,
  76, 130, 202, 30, 155, 87, 60, 253, 212, 224, 22, 103, 66, 111, 24,
  138, 23, 229, 18, 190, 78, 196, 214, 218, 158, 222, 73, 160, 251,
  245, 142, 187, 47, 238, 122, 169, 104, 121, 145, 21, 178, 7, 63,
  148, 194, 16, 137, 11, 34, 95, 33, 128, 127, 93, 154, 90, 144, 50,
  39, 53, 62, 204, 231, 191, 247, 151, 3, 255, 25, 48, 179, 72, 165,
  181, 209, 215, 94, 146, 42, 172, 86, 170, 198, 79, 184, 56, 210,
  150, 164, 125, 182, 118, 252, 107, 226, 156, 116, 4, 241, 69, 157,
  112, 89, 100, 113, 135, 32, 134, 91, 207, 101, 230, 45, 168, 2, 27,
  96, 37, 173, 174, 176, 185, 246, 28, 70, 97, 105, 52, 64, 126, 15,
  85, 71, 163, 35, 221, 81, 175, 58, 195, 92, 249, 206, 186, 197,
  234, 38, 44, 83, 13, 110, 133, 40, 132, 9, 211, 223, 205, 244, 65,
  129, 77, 82, 106, 220, 55, 200, 108, 193, 171, 250, 36, 225, 123,
  8, 12, 189, 177, 74, 120, 136, 149, 139, 227, 99, 232, 109, 233,
  203, 213, 254, 59, 0, 29, 57, 242, 239, 183, 14, 102, 88, 208, 228,
  166, 119, 114, 248, 235, 117, 75, 10, 49, 68, 80, 180, 143, 237,
  31, 26, 219, 153, 141, 51, 159, 17, 131, 20
};

static void
md2_transform(struct md2_ctx *ctx, const uint8_t *data)
{
  unsigned i;
  uint8_t t;
  
  memcpy(ctx->X + 16, data, MD2_DATA_SIZE);

  for (i = 0, t = ctx->C[15];
       i<MD2_DATA_SIZE; i++)
    {
      ctx->X[2 * MD2_DATA_SIZE + i]
	= ctx->X[i] ^ ctx->X[MD2_DATA_SIZE + i];
      t = (ctx->C[i] ^= S[data[i]^t]);
    }
  for (i = t = 0;
       i< MD2_DATA_SIZE + 2;
       t = (t + i) & 0xff, i++)
    {
      unsigned j;
      for (j = 0; j < 3 * MD2_DATA_SIZE; j++)
	t = (ctx->X[j] ^= S[t]);
    }
}

#if 0
static void
md2_final(struct md2_ctx *ctx)
{
  unsigned left = MD2_DATA_SIZE - ctx->index;
  memset(ctx->block + ctx->index, left, left);
  md2_transform(ctx, ctx->block);
}
#endif

void
md2_init(struct md2_ctx *ctx)
{
  memset(ctx, 0, sizeof(*ctx));
}

void
md2_update(struct md2_ctx *ctx,
	   unsigned length,
	   const uint8_t *data)
{
  if (ctx->index)
    {
      /* Try to fill partial block */
      unsigned left = MD2_DATA_SIZE - ctx->index;
      if (length < left)
	{
	  memcpy(ctx->block + ctx->index, data, length);
	  ctx->index += length;
	  return; /* Finished */
	}
      else
	{
	  memcpy(ctx->block + ctx->index, data, left);
	  md2_transform(ctx, ctx->block);
	  data += left;
	  length -= left;
	}
    }
  while (length >= MD2_DATA_SIZE)
    {
      md2_transform(ctx, data);
      data += MD2_DATA_SIZE;
      length -= MD2_DATA_SIZE;
    }
  if ((ctx->index = length))     /* This assignment is intended */
    /* Buffer leftovers */
    memcpy(ctx->block, data, length);
}

void
md2_digest(struct md2_ctx *ctx,
	   unsigned length,
	   uint8_t *digest)
{
  unsigned left;
  
  assert(length <= MD2_DIGEST_SIZE);

  left = MD2_DATA_SIZE - ctx->index;
  memset(ctx->block + ctx->index, left, left);
  md2_transform(ctx, ctx->block);
  
  md2_transform(ctx, ctx->C);
  memcpy(digest, ctx->X, length);
  md2_init(ctx);
}