/* 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, see <https://www.gnu.org/licenses/>.
 * SPDX-License-Identifier: LGPL-2.1-or-later
 *
 * 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 "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 */
} MD4_CONTEXT;

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

static void
md4_init (void *context, unsigned int flags)
{
  MD4_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;
}

#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 unsigned int
transform_blk ( void *c, const unsigned char *data )
{
  MD4_CONTEXT *ctx = c;
  u32 in[16];
  register u32 A = ctx->A;
  register u32 B = ctx->B;
  register u32 C = ctx->C;
  register u32 D = ctx->D;
  int i;

  for ( i = 0; i < 16; i++ )
    in[i] = buf_get_le32(data + i * 4);

  /* 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;

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

static void
md4_final( void *context )
{
  MD4_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 *
md4_read (void *context)
{
  MD4_CONTEXT *hd = context;
  return hd->bctx.buf;
}

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

const gcry_md_spec_t _gcry_digest_spec_md4 =
  {
    GCRY_MD_MD4, {0, 0},
    "MD4", asn, DIM (asn), oid_spec_md4,16,
    md4_init, _gcry_md_block_write, md4_final, md4_read, NULL,
    NULL,
    sizeof (MD4_CONTEXT)
  };
