chpms.c

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/*** WARNING - THIS CODE HAS NOT BEEN FINISHED! ***/
/*** The original PPPD code is written in a way to require either the UNIX DES
     encryption functions encrypt(3) and setkey(3) or the DES library libdes.
     Since both is not included in lwIP, MSCHAP currently does not work! */
/*****************************************************************************
* chpms.c - Network MicroSoft Challenge Handshake Authentication Protocol program file.
*
* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
* Copyright (c) 1997 by Global Election Systems Inc.  All rights reserved.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice and the following disclaimer are included verbatim in any 
* distributions. No written agreement, license, or royalty fee is required
* for any of the authorized uses.
*
* THIS SOFTWARE IS PROVIDED BY THE 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 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.
*
******************************************************************************
* REVISION HISTORY
*
* 03-01-01 Marc Boucher <marc@mbsi.ca>
*   Ported to lwIP.
* 97-12-08 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
*   Original based on BSD chap_ms.c.
*****************************************************************************/
/*
 * chap_ms.c - Microsoft MS-CHAP compatible implementation.
 *
 * Copyright (c) 1995 Eric Rosenquist, Strata Software Limited.
 * http://www.strataware.com/
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Eric Rosenquist.  The name of the author may not be used to
 * endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/*
 * Modifications by Lauri Pesonen / lpesonen@clinet.fi, april 1997
 *
 *   Implemented LANManager type password response to MS-CHAP challenges.
 *   Now pppd provides both NT style and LANMan style blocks, and the
 *   prefered is set by option "ms-lanman". Default is to use NT.
 *   The hash text (StdText) was taken from Win95 RASAPI32.DLL.
 *
 *   You should also use DOMAIN\\USERNAME as described in README.MSCHAP80
 */

#define USE_CRYPT

#include "lwip/opt.h"

#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#if MSCHAP_SUPPORT /* don't build if not configured for use in lwipopts.h */

#include "ppp.h"
#include "pppdebug.h"

#include "md4.h"
#ifndef USE_CRYPT
#include "des.h"
#endif
#include "chap.h"
#include "chpms.h"

#include <string.h>


/*************************/
/*** LOCAL DEFINITIONS ***/
/*************************/


/************************/
/*** LOCAL DATA TYPES ***/
/************************/
typedef struct {
    u_char LANManResp[24];
    u_char NTResp[24];
    u_char UseNT; /* If 1, ignore the LANMan response field */
} MS_ChapResponse;
/* We use MS_CHAP_RESPONSE_LEN, rather than sizeof(MS_ChapResponse),
   in case this struct gets padded. */



/***********************************/
/*** LOCAL FUNCTION DECLARATIONS ***/
/***********************************/

/* XXX Don't know what to do with these. */
extern void setkey(const char *);
extern void encrypt(char *, int);

static void DesEncrypt (u_char *, u_char *, u_char *);
static void MakeKey (u_char *, u_char *);

#ifdef USE_CRYPT
static void Expand (u_char *, u_char *);
static void Collapse (u_char *, u_char *);
#endif

static void ChallengeResponse(
  u_char *challenge, /* IN   8 octets */
  u_char *pwHash,    /* IN  16 octets */
  u_char *response   /* OUT 24 octets */
);
static void ChapMS_NT(
  char *rchallenge,
  int rchallenge_len,
  char *secret,
  int secret_len,
  MS_ChapResponse *response
);
static u_char Get7Bits(
  u_char *input,
  int startBit
);

static void
ChallengeResponse( u_char *challenge, /* IN   8 octets */
                   u_char *pwHash,    /* IN  16 octets */
                   u_char *response   /* OUT 24 octets */)
{
  u_char    ZPasswordHash[21];

  BZERO(ZPasswordHash, sizeof(ZPasswordHash));
  BCOPY(pwHash, ZPasswordHash, 16);

#if 0
  log_packet(ZPasswordHash, sizeof(ZPasswordHash), "ChallengeResponse - ZPasswordHash", LOG_DEBUG);
#endif

  DesEncrypt(challenge, ZPasswordHash +  0, response + 0);
  DesEncrypt(challenge, ZPasswordHash +  7, response + 8);
  DesEncrypt(challenge, ZPasswordHash + 14, response + 16);

#if 0
  log_packet(response, 24, "ChallengeResponse - response", LOG_DEBUG);
#endif
}


#ifdef USE_CRYPT
static void
DesEncrypt( u_char *clear, /* IN  8 octets */
            u_char *key,   /* IN  7 octets */
            u_char *cipher /* OUT 8 octets */)
{
  u_char des_key[8];
  u_char crypt_key[66];
  u_char des_input[66];

  MakeKey(key, des_key);

  Expand(des_key, crypt_key);
  setkey((char*)crypt_key);

#if 0
  CHAPDEBUG(LOG_INFO, ("DesEncrypt: 8 octet input : %02X%02X%02X%02X%02X%02X%02X%02X\n",
             clear[0], clear[1], clear[2], clear[3], clear[4], clear[5], clear[6], clear[7]));
#endif

  Expand(clear, des_input);
  encrypt((char*)des_input, 0);
  Collapse(des_input, cipher);

#if 0
  CHAPDEBUG(LOG_INFO, ("DesEncrypt: 8 octet output: %02X%02X%02X%02X%02X%02X%02X%02X\n",
             cipher[0], cipher[1], cipher[2], cipher[3], cipher[4], cipher[5], cipher[6], cipher[7]));
#endif
}

#else /* USE_CRYPT */

static void
DesEncrypt( u_char *clear, /* IN  8 octets */
            u_char *key,   /* IN  7 octets */
            u_char *cipher /* OUT 8 octets */)
{
  des_cblock    des_key;
  des_key_schedule  key_schedule;

  MakeKey(key, des_key);

  des_set_key(&des_key, key_schedule);

#if 0
  CHAPDEBUG(LOG_INFO, ("DesEncrypt: 8 octet input : %02X%02X%02X%02X%02X%02X%02X%02X\n",
             clear[0], clear[1], clear[2], clear[3], clear[4], clear[5], clear[6], clear[7]));
#endif

  des_ecb_encrypt((des_cblock *)clear, (des_cblock *)cipher, key_schedule, 1);

#if 0
  CHAPDEBUG(LOG_INFO, ("DesEncrypt: 8 octet output: %02X%02X%02X%02X%02X%02X%02X%02X\n",
             cipher[0], cipher[1], cipher[2], cipher[3], cipher[4], cipher[5], cipher[6], cipher[7]));
#endif
}

#endif /* USE_CRYPT */


static u_char
Get7Bits( u_char *input, int startBit)
{
  register unsigned int  word;

  word  = (unsigned)input[startBit / 8] << 8;
  word |= (unsigned)input[startBit / 8 + 1];

  word >>= 15 - (startBit % 8 + 7);

  return word & 0xFE;
}

#ifdef USE_CRYPT

/* in == 8-byte string (expanded version of the 56-bit key)
 * out == 64-byte string where each byte is either 1 or 0
 * Note that the low-order "bit" is always ignored by by setkey()
 */
static void
Expand(u_char *in, u_char *out)
{
  int j, c;
  int i;

  for(i = 0; i < 64; in++){
    c = *in;
    for(j = 7; j >= 0; j--) {
      *out++ = (c >> j) & 01;
    }
    i += 8;
  }
}

/* The inverse of Expand
 */
static void
Collapse(u_char *in, u_char *out)
{
  int j;
  int i;
  unsigned int c;

  for (i = 0; i < 64; i += 8, out++) {
    c = 0;
    for (j = 7; j >= 0; j--, in++) {
      c |= *in << j;
    }
    *out = c & 0xff;
  }
}
#endif

static void
MakeKey( u_char *key,    /* IN  56 bit DES key missing parity bits */
         u_char *des_key /* OUT 64 bit DES key with parity bits added */)
{
  des_key[0] = Get7Bits(key,  0);
  des_key[1] = Get7Bits(key,  7);
  des_key[2] = Get7Bits(key, 14);
  des_key[3] = Get7Bits(key, 21);
  des_key[4] = Get7Bits(key, 28);
  des_key[5] = Get7Bits(key, 35);
  des_key[6] = Get7Bits(key, 42);
  des_key[7] = Get7Bits(key, 49);
  
#ifndef USE_CRYPT
  des_set_odd_parity((des_cblock *)des_key);
#endif
  
#if 0
  CHAPDEBUG(LOG_INFO, ("MakeKey: 56-bit input : %02X%02X%02X%02X%02X%02X%02X\n",
             key[0], key[1], key[2], key[3], key[4], key[5], key[6]));
  CHAPDEBUG(LOG_INFO, ("MakeKey: 64-bit output: %02X%02X%02X%02X%02X%02X%02X%02X\n",
             des_key[0], des_key[1], des_key[2], des_key[3], des_key[4], des_key[5], des_key[6], des_key[7]));
#endif
}

static void
ChapMS_NT( char *rchallenge,
           int rchallenge_len,
           char *secret,
           int secret_len,
           MS_ChapResponse *response)
{
  int      i;
  MDstruct  md4Context;
  u_char    unicodePassword[MAX_NT_PASSWORD * 2];
  static int  low_byte_first = -1;

  LWIP_UNUSED_ARG(rchallenge_len);

  /* Initialize the Unicode version of the secret (== password). */
  /* This implicitly supports 8-bit ISO8859/1 characters. */
  BZERO(unicodePassword, sizeof(unicodePassword));
  for (i = 0; i < secret_len; i++) {
    unicodePassword[i * 2] = (u_char)secret[i];
  }
  MDbegin(&md4Context);
  MDupdate(&md4Context, unicodePassword, secret_len * 2 * 8);  /* Unicode is 2 bytes/char, *8 for bit count */

  if (low_byte_first == -1) {
    low_byte_first = (PP_HTONS((unsigned short int)1) != 1);
  }
  if (low_byte_first == 0) {
    /* @todo: arg type - u_long* or u_int* ? */
    MDreverse((unsigned int*)&md4Context);  /*  sfb 961105 */
  }

  MDupdate(&md4Context, NULL, 0);  /* Tell MD4 we're done */

  ChallengeResponse((u_char*)rchallenge, (u_char*)md4Context.buffer, response->NTResp);
}

#ifdef MSLANMAN
static u_char *StdText = (u_char *)"KGS!@#$%"; /* key from rasapi32.dll */

static void
ChapMS_LANMan( char *rchallenge,
               int rchallenge_len,
               char *secret,
               int secret_len,
               MS_ChapResponse  *response)
{
  int      i;
  u_char    UcasePassword[MAX_NT_PASSWORD]; /* max is actually 14 */
  u_char    PasswordHash[16];
  
  /* LANMan password is case insensitive */
  BZERO(UcasePassword, sizeof(UcasePassword));
  for (i = 0; i < secret_len; i++) {
    UcasePassword[i] = (u_char)toupper(secret[i]);
  }
  DesEncrypt( StdText, UcasePassword + 0, PasswordHash + 0 );
  DesEncrypt( StdText, UcasePassword + 7, PasswordHash + 8 );
  ChallengeResponse(rchallenge, PasswordHash, response->LANManResp);
}
#endif

void
ChapMS( chap_state *cstate, char *rchallenge, int rchallenge_len, char *secret, int secret_len)
{
  MS_ChapResponse response;
#ifdef MSLANMAN
  extern int ms_lanman;
#endif

#if 0
  CHAPDEBUG(LOG_INFO, ("ChapMS: secret is '%.*s'\n", secret_len, secret));
#endif
  BZERO(&response, sizeof(response));

  /* Calculate both always */
  ChapMS_NT(rchallenge, rchallenge_len, secret, secret_len, &response);

#ifdef MSLANMAN
  ChapMS_LANMan(rchallenge, rchallenge_len, secret, secret_len, &response);

  /* prefered method is set by option  */
  response.UseNT = !ms_lanman;
#else
  response.UseNT = 1;
#endif

  BCOPY(&response, cstate->response, MS_CHAP_RESPONSE_LEN);
  cstate->resp_length = MS_CHAP_RESPONSE_LEN;
}

#endif /* MSCHAP_SUPPORT */

#endif /* PPP_SUPPORT */