/* md5.c - MD5 Message-Digest Algorithm

 * Copyright (C) 1995,1996,1998,1999,2001,2002,

 *               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

 *

 * According to the definition of MD5 in RFC 1321 from April 1992.

 * NOTE: This is *not* the same file as the one from glibc.

 * Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.

 * heavily modified for GnuPG by Werner Koch <wk@gnupg.org>

 */

/* Test values:

 * ""                  D4 1D 8C D9 8F 00 B2 04  E9 80 09 98 EC F8 42 7E

 * "a"                 0C C1 75 B9 C0 F1 B6 A8  31 C3 99 E2 69 77 26 61

 * "abc                90 01 50 98 3C D2 4F B0  D6 96 3F 7D 28 E1 7F 72

 * "message digest"    F9 6B 69 7D 7C B7 93 8D  52 5A 2F 31 AA F1 61 D0

 */

#include <config.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "g10lib.h"

#include "cipher.h"

#include "bithelp.h"

#include "bufhelp.h"

#include "hash-common.h"

typedef struct {

    gcry_md_block_ctx_t bctx;

    u32 A,B,C,D;    /* chaining variables */

} MD5_CONTEXT;

static unsigned int

transform ( void *ctx, const unsigned char *data, size_t datalen );

static void

md5_init( void *context, unsigned int flags)

{

  MD5_CONTEXT *ctx = context;

  (void)flags;

  ctx->A = 0x67452301;

  ctx->B = 0xefcdab89;

  ctx->C = 0x98badcfe;

  ctx->D = 0x10325476;

  ctx->bctx.nblocks = 0;

  ctx->bctx.nblocks_high = 0;

  ctx->bctx.count = 0;

  ctx->bctx.blocksize_shift = _gcry_ctz(64);

  ctx->bctx.bwrite = transform;

}

/* These are the four functions used in the four steps of the MD5 algorithm

   and defined in the RFC 1321.  The first function is a little bit optimized

   (as found in Colin Plumbs public domain implementation).  */

/* #define FF(b, c, d) ((b & c) | (~b & d)) */

#define FF(b, c, d) (d ^ (b & (c ^ d)))

#define FG(b, c, d) FF (d, b, c)

#define FH(b, c, d) (b ^ c ^ d)

#define FI(b, c, d) (c ^ (b | ~d))

/****************

 * transform 64 bytes

 */

static unsigned int

transform_blk ( void *c, const unsigned char *data )

{

  MD5_CONTEXT *ctx = c;

  u32 correct_words[16];

  register u32 A = ctx->A;

  register u32 B = ctx->B;

  register u32 C = ctx->C;

  register u32 D = ctx->D;

  u32 *cwp = correct_words;

  int i;

  for ( i = 0; i < 16; i++ )

    correct_words[i] = buf_get_le32(data + i * 4);

#define OP(a, b, c, d, s, T) \

  do                   \

    {            \

      a += FF (b, c, d) + (*cwp++) + T;    \

      a = rol(a, s);         \

      a += b;          \

    }            \

  while (0)

  /* Before we start, one word about the strange constants.

     They are defined in RFC 1321 as

     T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64

  */

  /* Round 1.  */

  OP (A, B, C, D,  7, 0xd76aa478);

  OP (D, A, B, C, 12, 0xe8c7b756);

  OP (C, D, A, B, 17, 0x242070db);

  OP (B, C, D, A, 22, 0xc1bdceee);

  OP (A, B, C, D,  7, 0xf57c0faf);

  OP (D, A, B, C, 12, 0x4787c62a);

  OP (C, D, A, B, 17, 0xa8304613);

  OP (B, C, D, A, 22, 0xfd469501);

  OP (A, B, C, D,  7, 0x698098d8);

  OP (D, A, B, C, 12, 0x8b44f7af);

  OP (C, D, A, B, 17, 0xffff5bb1);

  OP (B, C, D, A, 22, 0x895cd7be);

  OP (A, B, C, D,  7, 0x6b901122);

  OP (D, A, B, C, 12, 0xfd987193);

  OP (C, D, A, B, 17, 0xa679438e);

  OP (B, C, D, A, 22, 0x49b40821);

#undef OP

#define OP(f, a, b, c, d, k, s, T)  \

    do                      \

      {                     \

  a += f (b, c, d) + correct_words[k] + T;          \

  a = rol(a, s);                  \

  a += b;                   \

      }                     \

    while (0)

  /* Round 2.  */

  OP (FG, A, B, C, D,  1,  5, 0xf61e2562);

  OP (FG, D, A, B, C,  6,  9, 0xc040b340);

  OP (FG, C, D, A, B, 11, 14, 0x265e5a51);

  OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);

  OP (FG, A, B, C, D,  5,  5, 0xd62f105d);

  OP (FG, D, A, B, C, 10,  9, 0x02441453);

  OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);

  OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);

  OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);

  OP (FG, D, A, B, C, 14,  9, 0xc33707d6);

  OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);

  OP (FG, B, C, D, A,  8, 20, 0x455a14ed);

  OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);

  OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);

  OP (FG, C, D, A, B,  7, 14, 0x676f02d9);

  OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);

  /* Round 3.  */

  OP (FH, A, B, C, D,  5,  4, 0xfffa3942);

  OP (FH, D, A, B, C,  8, 11, 0x8771f681);

  OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);

  OP (FH, B, C, D, A, 14, 23, 0xfde5380c);

  OP (FH, A, B, C, D,  1,  4, 0xa4beea44);

  OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);

  OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);

  OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);

  OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);

  OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);

  OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);

  OP (FH, B, C, D, A,  6, 23, 0x04881d05);

  OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);

  OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);

  OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);

  OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);

  /* Round 4.  */

  OP (FI, A, B, C, D,  0,  6, 0xf4292244);

  OP (FI, D, A, B, C,  7, 10, 0x432aff97);

  OP (FI, C, D, A, B, 14, 15, 0xab9423a7);

  OP (FI, B, C, D, A,  5, 21, 0xfc93a039);

  OP (FI, A, B, C, D, 12,  6, 0x655b59c3);

  OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);

  OP (FI, C, D, A, B, 10, 15, 0xffeff47d);

  OP (FI, B, C, D, A,  1, 21, 0x85845dd1);

  OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);

  OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);

  OP (FI, C, D, A, B,  6, 15, 0xa3014314);

  OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);

  OP (FI, A, B, C, D,  4,  6, 0xf7537e82);

  OP (FI, D, A, B, C, 11, 10, 0xbd3af235);

  OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);

  OP (FI, B, C, D, A,  9, 21, 0xeb86d391);

  /* Put checksum in context given as argument.  */

  ctx->A += A;

  ctx->B += B;

  ctx->C += C;

  ctx->D += D;

  return /*burn_stack*/ 80+6*sizeof(void*);

}

static unsigned int

transform ( void *c, const unsigned char *data, size_t nblks )

{

  unsigned int burn;

  do

    {

      burn = transform_blk (c, data);

      data += 64;

    }

  while (--nblks);

  return burn;

}

/* The routine final terminates the message-digest computation and

 * ends with the desired message digest in mdContext->digest[0...15].

 * The handle is prepared for a new MD5 cycle.

 * Returns 16 bytes representing the digest.

 */

static void

md5_final( void *context)

{

  MD5_CONTEXT *hd = context;

  u32 t, th, msb, lsb;

  byte *p;

  unsigned int burn;

  t = hd->bctx.nblocks;

  if (sizeof t == sizeof hd->bctx.nblocks)

    th = hd->bctx.nblocks_high;

  else

    th = hd->bctx.nblocks >> 32;

  /* multiply by 64 to make a byte count */

  lsb = t << 6;

  msb = (th << 6) | (t >> 26);

  /* add the count */

  t = lsb;

  if( (lsb += hd->bctx.count) < t )

    msb++;

  /* multiply by 8 to make a bit count */

  t = lsb;

  lsb <<= 3;

  msb <<= 3;

  msb |= t >> 29;

  if (hd->bctx.count < 56)  /* enough room */

    {

      hd->bctx.buf[hd->bctx.count++] = 0x80; /* pad */

      if (hd->bctx.count < 56)

  memset (&hd->bctx.buf[hd->bctx.count], 0, 56 - hd->bctx.count);

      /* append the 64 bit count */

      buf_put_le32(hd->bctx.buf + 56, lsb);

      buf_put_le32(hd->bctx.buf + 60, msb);

      burn = transform (hd, hd->bctx.buf, 1);

    }

  else /* need one extra block */

    {

      hd->bctx.buf[hd->bctx.count++] = 0x80; /* pad character */

      /* fill pad and next block with zeroes */

      memset (&hd->bctx.buf[hd->bctx.count], 0, 64 - hd->bctx.count + 56);

      /* append the 64 bit count */

      buf_put_le32(hd->bctx.buf + 64 + 56, lsb);

      buf_put_le32(hd->bctx.buf + 64 + 60, msb);

      burn = transform (hd, hd->bctx.buf, 2);

    }

  p = hd->bctx.buf;

#define X(a) do { buf_put_le32(p, hd->a); p += 4; } while(0)

  X(A);

  X(B);

  X(C);

  X(D);

#undef X

  hd->bctx.count = 0;

  _gcry_burn_stack (burn);

}

static byte *

md5_read( void *context )

{

  MD5_CONTEXT *hd = (MD5_CONTEXT *) context;

  return hd->bctx.buf;

}

static const byte asn[18] = /* Object ID is 1.2.840.113549.2.5 */

  { 0x30, 0x20, 0x30, 0x0c, 0x06, 0x08, 0x2a, 0x86,0x48,

    0x86, 0xf7, 0x0d, 0x02, 0x05, 0x05, 0x00, 0x04, 0x10 };

static const gcry_md_oid_spec_t oid_spec_md5[] =

  {

    /* iso.member-body.us.rsadsi.pkcs.pkcs-1.4 (md5WithRSAEncryption) */

    { "1.2.840.113549.1.1.4" },

    /* RSADSI digestAlgorithm MD5 */

    { "1.2.840.113549.2.5" },

    { NULL },

  };

const gcry_md_spec_t _gcry_digest_spec_md5 =

  {

    GCRY_MD_MD5, {0, 0},

    "MD5", asn, DIM (asn), oid_spec_md5, 16,

    md5_init, _gcry_md_block_write, md5_final, md5_read, NULL,

    NULL,

    sizeof (MD5_CONTEXT)

  };