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/*

 * 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

 */

#ifndef lint

/* static char rcsid[] = "$Id: chap_ms.c,v 1.2 2001-09-27 12:01:57 chris Exp $"; */

#endif

#ifdef CHAPMS

#include <stdio.h>

#include <string.h>

#include <ctype.h>

#include <sys/types.h>

#include <sys/time.h>

#include <syslog.h>

#include <unistd.h>

#ifdef HAVE_CRYPT_H

#include <crypt.h>

#endif

#include "pppd.h"

#include "chap.h"

#include "chap_ms.h"

#include "md4.h"

#ifndef USE_CRYPT

#include <des.h>

#endif

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. */

static void     ChallengeResponse __P((u_char *, u_char *, u_char *));

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

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

static u_char   Get7Bits __P((u_char *, int));

static void     ChapMS_NT __P((char *, int, char *, int, MS_ChapResponse *));

#ifdef MSLANMAN

static void     ChapMS_LANMan __P((char *, int, char *, int, MS_ChapResponse *));

#endif

#ifdef USE_CRYPT

static void     Expand __P((u_char *, u_char *));

static void     Collapse __P((u_char *, u_char *));

#endif

static void

ChallengeResponse(challenge, pwHash, response)

    u_char *challenge;  /* IN   8 octets */

    u_char *pwHash;     /* IN  16 octets */

    u_char *response;   /* OUT 24 octets */

{

    char    ZPasswordHash[21];

    BZERO(ZPasswordHash, sizeof(ZPasswordHash));

    BCOPY(pwHash, ZPasswordHash, MD4_SIGNATURE_SIZE);

#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(clear, key, cipher)

    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(crypt_key);

#if 0

    CHAPDEBUG((LOG_INFO, "DesEncrypt: 8 octet input : %02X%02X%02X%02X%02X%02X%02X%02X",

               clear[0], clear[1], clear[2], clear[3], clear[4], clear[5], clear[6], clear[7]));

#endif

    Expand(clear, des_input);

    encrypt(des_input, 0);

    Collapse(des_input, cipher);

#if 0

    CHAPDEBUG((LOG_INFO, "DesEncrypt: 8 octet output: %02X%02X%02X%02X%02X%02X%02X%02X",

               cipher[0], cipher[1], cipher[2], cipher[3], cipher[4], cipher[5], cipher[6], cipher[7]));

#endif

}

#else /* USE_CRYPT */

static void

DesEncrypt(clear, key, cipher)

    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",

               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",

               cipher[0], cipher[1], cipher[2], cipher[3], cipher[4], cipher[5], cipher[6], cipher[7]));

#endif

}

#endif /* USE_CRYPT */

static u_char Get7Bits(input, startBit)

    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(in, out)

    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(in, out)

    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(key, des_key)

    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",

               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",

               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(rchallenge, rchallenge_len, secret, secret_len, response)

    char *rchallenge;

    int rchallenge_len;

    char *secret;

    int secret_len;

    MS_ChapResponse    *response;

{

    int                 i;

    MD4_CTX             md4Context;

    u_char              hash[MD4_SIGNATURE_SIZE];

    u_char              unicodePassword[MAX_NT_PASSWORD * 2];

    /* 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];

    MD4Init(&md4Context);

    MD4Update(&md4Context, unicodePassword, secret_len * 2 * 8);        /* Unicode is 2 bytes/char, *8 for bit count */

    MD4Final(hash, &md4Context);        /* Tell MD4 we're done */

    ChallengeResponse(rchallenge, hash, response->NTResp);

}

#ifdef MSLANMAN

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

static void

ChapMS_LANMan(rchallenge, rchallenge_len, secret, secret_len, response)

    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[MD4_SIGNATURE_SIZE];

    /* 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(cstate, rchallenge, rchallenge_len, secret, secret_len)

    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'", 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 /* CHAPMS */