crypt-nthash.c

/*-
 * Copyright (c) 2003 Michael Bretterklieber
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The bogus 'gensalt_nthash_rn' function and all modifications to the other
 * parts of this file are
 *
 * Copyright (c) 2017 Björn Esser <besser82@fedoraproject.org>
 * All rights reserved.
 *
 * and is provided under the same licensing terms and conditions as the
 * other parts of this file.
 */

#include "crypt-port.h"
#include "alg-md4.h"
#include "crypt-private.h"

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>

#if INCLUDE_nthash

/*
 * NT HASH = md4(str2unicode(phrase))
 */

void
crypt_nthash_rn (const char *phrase, size_t ARG_UNUSED (phr_size),
                 const char *setting, size_t ARG_UNUSED (set_size),
                 uint8_t *output, size_t out_size,
                 void *scratch, size_t scr_size)
{
  size_t unipwLen;
  int i;
  static const char hexconvtab[] = "0123456789abcdef";
  static const char *magic = "$3$";
  uint16_t unipw[128];
  unsigned char hash[16];
  const char *s;
  struct md4_ctx *ctx = scratch;

  if ((out_size < 4 + 32) ||
      (scr_size < sizeof (struct md4_ctx)))
    {
      errno = ERANGE;
      return;
    }

  if (strncmp (setting, magic, strlen (magic)))
    {
      errno = EINVAL;
      return;
    }

  XCRYPT_SECURE_MEMSET (unipw, sizeof unipw);
  /* convert to unicode (thanx Archie) */
  unipwLen = 0;
  for (s = phrase; unipwLen < sizeof(unipw) / 2 && *s; s++)
    unipw[unipwLen++] = htons((uint16_t)(*s << 8));

  /* Compute MD4 of Unicode password */
  md4_init_ctx (ctx);
  md4_process_bytes ((unsigned char *)unipw, ctx, unipwLen*sizeof(uint16_t));
  md4_finish_ctx (ctx, hash);

  output = (uint8_t *)stpcpy ((char *)output, magic);
  *output++ = '$';
  for (i = 0; i < 16; i++)
    {
      *output++ = (uint8_t)hexconvtab[hash[i] >> 4];
      *output++ = (uint8_t)hexconvtab[hash[i] & 0xf];
    }
  *output = '\0';
}

/* This function does not return any valid salt,
   since the NTHASH crypt function simply ignores
   any setting passed to it.  Anyways, the string
   returned in OUTPUT will start with the correct
   magic string '$3$', so it can be used as
   SETTING for the crypt function.  */
void
gensalt_nthash_rn (unsigned long count,
                   const uint8_t *rbytes,
                   size_t nrbytes,
                   uint8_t *output,
                   size_t o_size)
{
  static const char *salt = "$3$__not_used__";
  struct md4_ctx ctx;
  unsigned char hashbuf[16];
  char hashstr[14 + 1];
  unsigned long i;

  /* Minimal O_SIZE to store the fake salt.
     At least 1 byte of RBYTES is needed
     to calculate the MD4 hash used in the
     fake salt.  */
  if ((o_size < 29) || (nrbytes < 1))
    {
      errno = ERANGE;
      return;
    }
  if (count != 0)
    {
      errno = EINVAL;
      return;
    }

  md4_init_ctx (&ctx);
  for (i = 0; i < 20; i++)
    {
      md4_process_bytes (salt, &ctx, (i % 15) + 1);
      md4_process_bytes (rbytes, &ctx, nrbytes);
      md4_process_bytes (salt, &ctx, 15);
      md4_process_bytes (salt, &ctx, 15 - (i % 15));
    }
  md4_finish_ctx (&ctx, &hashbuf);

  for (i = 0; i < 7; i++)
    sprintf (&(hashstr[i * 2]), "%02x", hashbuf[i]);

  memcpy (output, salt, 15);
  memcpy (output + 15, hashstr, 14);
}

#endif