/* md4.c - MD4 Message-Digest Algorithm
 * Copyright (C) 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
 *
 * Based on md5.c in libgcrypt, but rewritten to compute md4 checksums
 * using a public domain md4 implementation with the following comments:
 *
 * Modified by Wei Dai from Andrew M. Kuchling's md4.c
 * The original code and all modifications are in the public domain.
 *
 * This is the original introductory comment:
 *
 *  md4.c : MD4 hash algorithm.
 *
 * Part of the Python Cryptography Toolkit, version 1.1
 *
 * Distribute and use freely; there are no restrictions on further
 * dissemination and usage except those imposed by the laws of your
 * country of residence.
 *
 */

/* MD4 test suite:
 * MD4 ("") = 31d6cfe0d16ae931b73c59d7e0c089c0
 * MD4 ("a") = bde52cb31de33e46245e05fbdbd6fb24
 * MD4 ("abc") = a448017aaf21d8525fc10ae87aa6729d
 * MD4 ("message digest") = d9130a8164549fe818874806e1c7014b
 * MD4 ("abcdefghijklmnopqrstuvwxyz") = d79e1c308aa5bbcdeea8ed63df412da9
 * MD4 ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789") =
 * 043f8582f241db351ce627e153e7f0e4
 * MD4 ("123456789012345678901234567890123456789012345678901234567890123456
 * 78901234567890") = e33b4ddc9c38f2199c3e7b164fcc0536
 */

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

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

#include "bithelp.h"


typedef struct {
    u32 A,B,C,D;	  /* chaining variables */
    u32  nblocks;
    byte buf[64];
    int  count;
} MD4_CONTEXT;


static void
md4_init( void *context )
{
  MD4_CONTEXT *ctx = context;

  ctx->A = 0x67452301;
  ctx->B = 0xefcdab89;
  ctx->C = 0x98badcfe;
  ctx->D = 0x10325476;

  ctx->nblocks = 0;
  ctx->count = 0;
}

#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))


/****************
 * transform 64 bytes
 */
static void
transform ( MD4_CONTEXT *ctx, const unsigned char *data )
{
  u32 in[16];
  register u32 A = ctx->A;
  register u32 B = ctx->B;
  register u32 C = ctx->C;
  register u32 D = ctx->D;

#ifdef WORDS_BIGENDIAN
  {
    int i;
    byte *p2;
    const byte *p1;
    for(i=0, p1=data, p2=(byte*)in; i < 16; i++, p2 += 4 )
      {
	p2[3] = *p1++;
	p2[2] = *p1++;
	p2[1] = *p1++;
	p2[0] = *p1++;
      }
  }
#else
  memcpy (in, data, 64);
#endif

  /* Round 1.  */
#define function(a,b,c,d,k,s) a=rol(a+F(b,c,d)+in[k],s);
  function(A,B,C,D, 0, 3);
  function(D,A,B,C, 1, 7);
  function(C,D,A,B, 2,11);
  function(B,C,D,A, 3,19);
  function(A,B,C,D, 4, 3);
  function(D,A,B,C, 5, 7);
  function(C,D,A,B, 6,11);
  function(B,C,D,A, 7,19);
  function(A,B,C,D, 8, 3);
  function(D,A,B,C, 9, 7);
  function(C,D,A,B,10,11);
  function(B,C,D,A,11,19);
  function(A,B,C,D,12, 3);
  function(D,A,B,C,13, 7);
  function(C,D,A,B,14,11);
  function(B,C,D,A,15,19);

#undef function

  /* Round 2.  */
#define function(a,b,c,d,k,s) a=rol(a+G(b,c,d)+in[k]+0x5a827999,s);

  function(A,B,C,D, 0, 3);
  function(D,A,B,C, 4, 5);
  function(C,D,A,B, 8, 9);
  function(B,C,D,A,12,13);
  function(A,B,C,D, 1, 3);
  function(D,A,B,C, 5, 5);
  function(C,D,A,B, 9, 9);
  function(B,C,D,A,13,13);
  function(A,B,C,D, 2, 3);
  function(D,A,B,C, 6, 5);
  function(C,D,A,B,10, 9);
  function(B,C,D,A,14,13);
  function(A,B,C,D, 3, 3);
  function(D,A,B,C, 7, 5);
  function(C,D,A,B,11, 9);
  function(B,C,D,A,15,13);

#undef function

  /* Round 3.  */
#define function(a,b,c,d,k,s) a=rol(a+H(b,c,d)+in[k]+0x6ed9eba1,s);

  function(A,B,C,D, 0, 3);
  function(D,A,B,C, 8, 9);
  function(C,D,A,B, 4,11);
  function(B,C,D,A,12,15);
  function(A,B,C,D, 2, 3);
  function(D,A,B,C,10, 9);
  function(C,D,A,B, 6,11);
  function(B,C,D,A,14,15);
  function(A,B,C,D, 1, 3);
  function(D,A,B,C, 9, 9);
  function(C,D,A,B, 5,11);
  function(B,C,D,A,13,15);
  function(A,B,C,D, 3, 3);
  function(D,A,B,C,11, 9);
  function(C,D,A,B, 7,11);
  function(B,C,D,A,15,15);


  /* Put checksum in context given as argument.  */
  ctx->A += A;
  ctx->B += B;
  ctx->C += C;
  ctx->D += D;
}



/* The routine updates the message-digest context to
 * account for the presence of each of the characters inBuf[0..inLen-1]
 * in the message whose digest is being computed.
 */
static void
md4_write ( void *context, const void *inbuf_arg, size_t inlen)
{
  const unsigned char *inbuf = inbuf_arg;
  MD4_CONTEXT *hd = context;

  if( hd->count == 64 ) /* flush the buffer */
    { 
      transform( hd, hd->buf );
      _gcry_burn_stack (80+6*sizeof(void*));
      hd->count = 0;
      hd->nblocks++;
    }
  if( !inbuf )
    return;

  if( hd->count )
    {
      for( ; inlen && hd->count < 64; inlen-- )
        hd->buf[hd->count++] = *inbuf++;
      md4_write( hd, NULL, 0 );
      if( !inlen )
        return;
    }
  _gcry_burn_stack (80+6*sizeof(void*));

  while( inlen >= 64 )
    {
      transform( hd, inbuf );
      hd->count = 0;
      hd->nblocks++;
      inlen -= 64;
      inbuf += 64;
    }
  for( ; inlen && hd->count < 64; inlen-- )
    hd->buf[hd->count++] = *inbuf++;
}



/* 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 MD4 cycle.
 * Returns 16 bytes representing the digest.
 */

static void
md4_final( void *context )
{
  MD4_CONTEXT *hd = context;
  u32 t, msb, lsb;
  byte *p;

  md4_write(hd, NULL, 0); /* flush */;

  t = hd->nblocks;
  /* multiply by 64 to make a byte count */
  lsb = t << 6;
  msb = t >> 26;
  /* add the count */
  t = lsb;
  if( (lsb += hd->count) < t )
    msb++;
  /* multiply by 8 to make a bit count */
  t = lsb;
  lsb <<= 3;
  msb <<= 3;
  msb |= t >> 29;
  
  if( hd->count < 56 )  /* enough room */
    {
      hd->buf[hd->count++] = 0x80; /* pad */
      while( hd->count < 56 )
        hd->buf[hd->count++] = 0;  /* pad */
    }
  else /* need one extra block */ 
    { 
      hd->buf[hd->count++] = 0x80; /* pad character */
      while( hd->count < 64 )
        hd->buf[hd->count++] = 0;
      md4_write(hd, NULL, 0);  /* flush */;
      memset(hd->buf, 0, 56 ); /* fill next block with zeroes */
    }
  /* append the 64 bit count */
  hd->buf[56] = lsb	   ;
  hd->buf[57] = lsb >>  8;
  hd->buf[58] = lsb >> 16;
  hd->buf[59] = lsb >> 24;
  hd->buf[60] = msb	   ;
  hd->buf[61] = msb >>  8;
  hd->buf[62] = msb >> 16;
  hd->buf[63] = msb >> 24;
  transform( hd, hd->buf );
  _gcry_burn_stack (80+6*sizeof(void*));

  p = hd->buf;
#ifdef WORDS_BIGENDIAN
#define X(a) do { *p++ = hd->a      ; *p++ = hd->a >> 8;      \
		  *p++ = hd->a >> 16; *p++ = hd->a >> 24; } while(0)
#else /* little endian */
#define X(a) do { *(u32*)p = (*hd).a ; p += 4; } while(0)
#endif
  X(A);
  X(B);
  X(C);
  X(D);
#undef X

}

static byte *
md4_read (void *context)
{
  MD4_CONTEXT *hd = context;
  return hd->buf;
}

static byte asn[18] = /* Object ID is 1.2.840.113549.2.4 */
  { 0x30, 0x20, 0x30, 0x0c, 0x06, 0x08, 0x2a, 0x86,0x48,
    0x86, 0xf7, 0x0d, 0x02, 0x04, 0x05, 0x00, 0x04, 0x10 };

static gcry_md_oid_spec_t oid_spec_md4[] =
  {
    /* iso.member-body.us.rsadsi.digestAlgorithm.md4 */
    { "1.2.840.113549.2.4" },
    { NULL },
  };

gcry_md_spec_t _gcry_digest_spec_md4 =
  {
    "MD4", asn, DIM (asn), oid_spec_md4,16,
    md4_init, md4_write, md4_final, md4_read,
    sizeof (MD4_CONTEXT)
  };