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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.
*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/time.h>
#include <syslog.h>
#include <string.h>
#include "chap.h"
#include "chap_ms.h"
#include <des.h>
/* unused, for documentation only */
/* only NTResp is filled in for FreeBSD */
typedef struct {
u_char LANManResp[24];
u_char NTResp[24];
u_char UseNT; /* If 1, ignore the LANMan response field */
} MS_ChapResponse;
static void DesEncrypt(u_char *, u_char *, u_char *);
static void MakeKey(u_char *, u_char *);
static void /* IN 8 octets IN 16 octets OUT 24 octets */
ChallengeResponse(u_char* challenge, u_char* pwHash, u_char* response)
{
char ZPasswordHash[21];
bzero(ZPasswordHash, sizeof(ZPasswordHash));
bcopy(pwHash, ZPasswordHash, 16);
DesEncrypt(challenge, ZPasswordHash + 0, response + 0);
DesEncrypt(challenge, ZPasswordHash + 7, response + 8);
DesEncrypt(challenge, ZPasswordHash + 14, response + 16);
}
static void /* IN 8 octets IN 7 octest OUT 8 octets */
DesEncrypt(u_char* clear, u_char* key, u_char* cipher)
{
des_cblock des_key;
des_key_schedule key_schedule;
MakeKey(key, des_key);
des_set_key(&des_key, key_schedule);
des_ecb_encrypt((des_cblock *)clear, (des_cblock *)cipher, key_schedule, 1);
}
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;
}
/* IN 56 bit DES key missing parity bits
OUT 64 bit DES key with parity bits added */
static void MakeKey(u_char* key, u_char* des_key)
{
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);
des_set_odd_parity((des_cblock *)des_key);
}
/* passwordHash 16-bytes MD4 hashed password
challenge 8-bytes peer CHAP challenge
since passwordHash is in a 24-byte buffer, response is written in there */
void
ChapMS(char* passwordHash, char* challenge, int challenge_len)
{
u_char response[24];
ChallengeResponse(challenge, passwordHash, response);
bcopy(response, passwordHash, 24);
passwordHash += 24;
*passwordHash = 1;
}
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