/* crc.c - Cyclic redundancy checks.
 * Copyright (C) 2003 Free Software Foundation, Inc.
 *
 * This file is part of Libgcrypt.
 *
 * Libgcrypt 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.
 *
 * Libgcrypt 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 *
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "g10lib.h"
#include "cipher.h"

#include "bithelp.h"

/* Table of CRCs of all 8-bit messages.  Generated by running code
   from RFC 1952 modified to print out the table. */
static u32 crc32_table[256] = {
  0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
  0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
  0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
  0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
  0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
  0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
  0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
  0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
  0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
  0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
  0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
  0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
  0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
  0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
  0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
  0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
  0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
  0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
  0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
  0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
  0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
  0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
  0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
  0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
  0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
  0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
  0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
  0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
  0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
  0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
  0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
  0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
  0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
  0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
  0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
  0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
  0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
  0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
  0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
  0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
  0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
  0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
  0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
};

/*
 * The following function was extracted from RFC 1952 by Simon
 * Josefsson, for the Shishi project, and modified to be compatible
 * with the modified CRC-32 used by RFC 1510, and subsequently
 * modified for GNU Libgcrypt to allow it to be used for calculating
 * both unmodified CRC-32 and modified CRC-32 values.  Original
 * copyright and notice from the document follows:
 *
 *    Copyright (c) 1996 L. Peter Deutsch
 *
 *    Permission is granted to copy and distribute this document for
 *    any purpose and without charge, including translations into
 *    other languages and incorporation into compilations, provided
 *    that the copyright notice and this notice are preserved, and
 *    that any substantive changes or deletions from the original are
 *    clearly marked.
 *
 * The copyright on RFCs, and consequently the function below, are
 * supposedly also retroactively claimed by the Internet Society
 * (according to rfc-editor@rfc-editor.org), with the following
 * copyright notice:
 *
 *    Copyright (C) The Internet Society.  All Rights Reserved.
 *
 *    This document and translations of it may be copied and furnished
 *    to others, and derivative works that comment on or otherwise
 *    explain it or assist in its implementation may be prepared,
 *    copied, published and distributed, in whole or in part, without
 *    restriction of any kind, provided that the above copyright
 *    notice and this paragraph are included on all such copies and
 *    derivative works.  However, this document itself may not be
 *    modified in any way, such as by removing the copyright notice or
 *    references to the Internet Society or other Internet
 *    organizations, except as needed for the purpose of developing
 *    Internet standards in which case the procedures for copyrights
 *    defined in the Internet Standards process must be followed, or
 *    as required to translate it into languages other than English.
 *
 *    The limited permissions granted above are perpetual and will not be
 *    revoked by the Internet Society or its successors or assigns.
 *
 *    This document and the information contained herein is provided
 *    on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
 *    ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
 *    IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE
 *    OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY
 *    IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
 *    PARTICULAR PURPOSE.
 *
 */
static u32
update_crc32 (u32 crc, const void *buf_arg, size_t len)
{
  const char *buf = buf_arg;
  size_t n;

  for (n = 0; n < len; n++)
    crc = crc32_table[(crc ^ buf[n]) & 0xff] ^ (crc >> 8);

  return crc;
}

typedef struct
{
  u32 CRC;
  byte buf[4];
}
CRC_CONTEXT;

/* CRC32 */

static void
crc32_init (void *context, unsigned int flags)
{
  CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;

  (void)flags;

  ctx->CRC = 0 ^ 0xffffffffL;
}

static void
crc32_write (void *context, const void *inbuf, size_t inlen)
{
  CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;
  if (!inbuf)
    return;
  ctx->CRC = update_crc32 (ctx->CRC, inbuf, inlen);
}

static byte *
crc32_read (void *context)
{
  CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;
  return ctx->buf;
}

static void
crc32_final (void *context)
{
  CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;
  ctx->CRC ^= 0xffffffffL;
  ctx->buf[0] = (ctx->CRC >> 24) & 0xFF;
  ctx->buf[1] = (ctx->CRC >> 16) & 0xFF;
  ctx->buf[2] = (ctx->CRC >>  8) & 0xFF;
  ctx->buf[3] = (ctx->CRC      ) & 0xFF;
}

/* CRC32 a'la RFC 1510 */
static void
crc32rfc1510_init (void *context, unsigned int flags)
{
  CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;

  (void)flags;

  ctx->CRC = 0;
}

static void
crc32rfc1510_final (void *context)
{
  CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;
  ctx->buf[0] = (ctx->CRC >> 24) & 0xFF;
  ctx->buf[1] = (ctx->CRC >> 16) & 0xFF;
  ctx->buf[2] = (ctx->CRC >>  8) & 0xFF;
  ctx->buf[3] = (ctx->CRC      ) & 0xFF;
}

/* CRC24 a'la RFC 2440 */
/*
 * The following CRC 24 routines are adapted from RFC 2440, which has
 * the following copyright notice:
 *
 *   Copyright (C) The Internet Society (1998).  All Rights Reserved.
 *
 *   This document and translations of it may be copied and furnished
 *   to others, and derivative works that comment on or otherwise
 *   explain it or assist in its implementation may be prepared,
 *   copied, published and distributed, in whole or in part, without
 *   restriction of any kind, provided that the above copyright notice
 *   and this paragraph are included on all such copies and derivative
 *   works.  However, this document itself may not be modified in any
 *   way, such as by removing the copyright notice or references to
 *   the Internet Society or other Internet organizations, except as
 *   needed for the purpose of developing Internet standards in which
 *   case the procedures for copyrights defined in the Internet
 *   Standards process must be followed, or as required to translate
 *   it into languages other than English.
 *
 *   The limited permissions granted above are perpetual and will not be
 *   revoked by the Internet Society or its successors or assigns.
 *
 *   This document and the information contained herein is provided on
 *   an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
 *   ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
 *   IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE
 *   OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY
 *   IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
 *   PURPOSE.
 */

#define CRC24_INIT 0xb704ceL
#define CRC24_POLY 0x1864cfbL

static void
crc24rfc2440_init (void *context, unsigned int flags)
{
  CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;

  (void)flags;

  ctx->CRC = CRC24_INIT;
}

static void
crc24rfc2440_write (void *context, const void *inbuf_arg, size_t inlen)
{
  const unsigned char *inbuf = inbuf_arg;
  int i;
  CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;

  if (!inbuf)
    return;

  while (inlen--) {
    ctx->CRC ^= (*inbuf++) << 16;
    for (i = 0; i < 8; i++) {
      ctx->CRC <<= 1;
      if (ctx->CRC & 0x1000000)
	ctx->CRC ^= CRC24_POLY;
    }
  }
}

static void
crc24rfc2440_final (void *context)
{
  CRC_CONTEXT *ctx = (CRC_CONTEXT *) context;
  ctx->buf[0] = (ctx->CRC >> 16) & 0xFF;
  ctx->buf[1] = (ctx->CRC >>  8) & 0xFF;
  ctx->buf[2] = (ctx->CRC      ) & 0xFF;
}

/* We allow the CRC algorithms even in FIPS mode because they are
   actually no cryptographic primitives.  */

gcry_md_spec_t _gcry_digest_spec_crc32 =
  {
    GCRY_MD_CRC32, {0, 1},
    "CRC32", NULL, 0, NULL, 4,
    crc32_init, crc32_write, crc32_final, crc32_read,
    sizeof (CRC_CONTEXT)
  };

gcry_md_spec_t _gcry_digest_spec_crc32_rfc1510 =
  {
    GCRY_MD_CRC32_RFC1510, {0, 1},
    "CRC32RFC1510", NULL, 0, NULL, 4,
    crc32rfc1510_init, crc32_write,
    crc32rfc1510_final, crc32_read,
    sizeof (CRC_CONTEXT)
  };

gcry_md_spec_t _gcry_digest_spec_crc24_rfc2440 =
  {
    GCRY_MD_CRC24_RFC2440, {0, 1},
    "CRC24RFC2440", NULL, 0, NULL, 3,
    crc24rfc2440_init, crc24rfc2440_write,
    crc24rfc2440_final, crc32_read,
    sizeof (CRC_CONTEXT)
  };
