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|
/* $OpenBSD: chap_ms.c,v 1.1 2024/07/14 13:44:30 yasuoka Exp $ */
/*
* Copyright (c) 2010-2013 Reyk Floeter <reyk@openbsd.org>
* Copyright (c) 1997-2001 Brian Somers <brian@Awfulhak.org>
* Copyright (c) 1997 Gabor Kincses <gabor@acm.org>
* Copyright (c) 1995 Eric Rosenquist
*
* 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.
*/
#include <sys/types.h>
#include <ctype.h>
#include <string.h>
#include <stdio.h>
#include <openssl/evp.h>
#include <openssl/des.h>
#include <openssl/md4.h>
#include <openssl/md5.h>
#include <openssl/sha.h>
#include "chap_ms.h"
/*
* Documentation & specifications:
*
* MS-CHAP (CHAP80) RFC2433
* MS-CHAP-V2 (CHAP81) RFC2759
* MPPE key management RFC3079
*
* Security analysis:
* Schneier/Mudge/Wagner, "MS-CHAP-v2", Oct 99
* "It is unclear to us why this protocol is so complicated."
*/
static u_int8_t sha1_pad1[40] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
static u_int8_t sha1_pad2[40] = {
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2
};
u_int8_t get7bits(u_int8_t *, int);
void mschap_des_addparity(u_int8_t *, u_int8_t *);
void mschap_des_encrypt(u_int8_t *, u_int8_t *, u_int8_t *);
void mschap_challenge_response(u_int8_t *, u_int8_t *, u_int8_t *);
u_int8_t
get7bits(u_int8_t *in, int start)
{
u_int word;
word = (u_int)in[start / 8] << 8;
word |= (u_int)in[start / 8 + 1];
word >>= 15 - (start % 8 + 7);
return (word & 0xfe);
}
/* IN 56 bit DES key missing parity bits
OUT 64 bit DES key with parity bits added */
void
mschap_des_addparity(u_int8_t *key, u_int8_t *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);
}
void
mschap_des_encrypt(u_int8_t *clear, u_int8_t *key, u_int8_t *cipher)
{
DES_cblock des_key;
DES_key_schedule key_schedule;
mschap_des_addparity(key, des_key);
DES_set_key(&des_key, &key_schedule);
DES_ecb_encrypt((DES_cblock *)clear, (DES_cblock *)cipher,
&key_schedule, 1);
}
void
mschap_challenge_response(u_int8_t *challenge, u_int8_t *pwhash,
u_int8_t *response)
{
u_int8_t padpwhash[21 + 1];
bzero(&padpwhash, sizeof(padpwhash));
memcpy(padpwhash, pwhash, MSCHAP_HASH_SZ);
mschap_des_encrypt(challenge, padpwhash + 0, response + 0);
mschap_des_encrypt(challenge, padpwhash + 7, response + 8);
mschap_des_encrypt(challenge, padpwhash + 14, response + 16);
}
void
mschap_ntpassword_hash(u_int8_t *in, int inlen, u_int8_t *hash)
{
EVP_MD_CTX *ctx;
u_int mdlen;
ctx = EVP_MD_CTX_new();
EVP_DigestInit_ex(ctx, EVP_md4(), NULL);
EVP_DigestUpdate(ctx, in, inlen);
EVP_DigestFinal_ex(ctx, hash, &mdlen);
EVP_MD_CTX_free(ctx);
}
void
mschap_challenge_hash(u_int8_t *peer_challenge, u_int8_t *auth_challenge,
u_int8_t *username, int usernamelen, u_int8_t *challenge)
{
EVP_MD_CTX *ctx;
u_int8_t md[SHA_DIGEST_LENGTH];
u_int mdlen;
u_int8_t *name;
if ((name = strrchr(username, '\\')) == NULL)
name = username;
else
name++;
ctx = EVP_MD_CTX_new();
EVP_DigestInit_ex(ctx, EVP_sha1(), NULL);
EVP_DigestUpdate(ctx, peer_challenge, MSCHAPV2_CHALLENGE_SZ);
EVP_DigestUpdate(ctx, auth_challenge, MSCHAPV2_CHALLENGE_SZ);
EVP_DigestUpdate(ctx, name, strlen(name));
EVP_DigestFinal_ex(ctx, md, &mdlen);
EVP_MD_CTX_free(ctx);
memcpy(challenge, md, MSCHAP_CHALLENGE_SZ);
}
void
mschap_nt_response(u_int8_t *auth_challenge, u_int8_t *peer_challenge,
u_int8_t *username, int usernamelen, u_int8_t *password, int passwordlen,
u_int8_t *response)
{
u_int8_t challenge[MSCHAP_CHALLENGE_SZ];
u_int8_t password_hash[MSCHAP_HASH_SZ];
mschap_challenge_hash(peer_challenge, auth_challenge,
username, usernamelen, challenge);
mschap_ntpassword_hash(password, passwordlen, password_hash);
mschap_challenge_response(challenge, password_hash, response);
}
void
mschap_auth_response(u_int8_t *password, int passwordlen,
u_int8_t *ntresponse, u_int8_t *auth_challenge, u_int8_t *peer_challenge,
u_int8_t *username, int usernamelen, u_int8_t *auth_response)
{
EVP_MD_CTX *ctx;
u_int8_t password_hash[MSCHAP_HASH_SZ];
u_int8_t password_hash2[MSCHAP_HASH_SZ];
u_int8_t challenge[MSCHAP_CHALLENGE_SZ];
u_int8_t md[SHA_DIGEST_LENGTH], *ptr;
u_int mdlen;
int i;
const u_int8_t hex[] = "0123456789ABCDEF";
static u_int8_t magic1[39] = {
0x4D, 0x61, 0x67, 0x69, 0x63, 0x20, 0x73, 0x65, 0x72, 0x76,
0x65, 0x72, 0x20, 0x74, 0x6F, 0x20, 0x63, 0x6C, 0x69, 0x65,
0x6E, 0x74, 0x20, 0x73, 0x69, 0x67, 0x6E, 0x69, 0x6E, 0x67,
0x20, 0x63, 0x6F, 0x6E, 0x73, 0x74, 0x61, 0x6E, 0x74
};
static u_int8_t magic2[41] = {
0x50, 0x61, 0x64, 0x20, 0x74, 0x6F, 0x20, 0x6D, 0x61, 0x6B,
0x65, 0x20, 0x69, 0x74, 0x20, 0x64, 0x6F, 0x20, 0x6D, 0x6F,
0x72, 0x65, 0x20, 0x74, 0x68, 0x61, 0x6E, 0x20, 0x6F, 0x6E,
0x65, 0x20, 0x69, 0x74, 0x65, 0x72, 0x61, 0x74, 0x69, 0x6F,
0x6E
};
mschap_ntpassword_hash(password, passwordlen, password_hash);
mschap_ntpassword_hash(password_hash, MSCHAP_HASH_SZ, password_hash2);
ctx = EVP_MD_CTX_new();
EVP_DigestInit_ex(ctx, EVP_sha1(), NULL);
EVP_DigestUpdate(ctx, password_hash2, sizeof(password_hash2));
EVP_DigestUpdate(ctx, ntresponse, 24);
EVP_DigestUpdate(ctx, magic1, 39);
EVP_DigestFinal_ex(ctx, md, &mdlen);
mschap_challenge_hash(peer_challenge, auth_challenge,
username, usernamelen, challenge);
EVP_DigestInit_ex(ctx, EVP_sha1(), NULL);
EVP_DigestUpdate(ctx, md, sizeof(md));
EVP_DigestUpdate(ctx, challenge, sizeof(challenge));
EVP_DigestUpdate(ctx, magic2, 41);
EVP_DigestFinal_ex(ctx, md, &mdlen);
EVP_MD_CTX_free(ctx);
/*
* Encode the value of 'Digest' as "S=" followed by
* 40 ASCII hexadecimal digits and return it in
* AuthenticatorResponse.
* For example,
* "S=0123456789ABCDEF0123456789ABCDEF01234567"
*/
ptr = auth_response;
*ptr++ = 'S';
*ptr++ = '=';
for (i = 0; i < SHA_DIGEST_LENGTH; i++) {
*ptr++ = hex[md[i] >> 4];
*ptr++ = hex[md[i] & 0x0f];
}
}
void
mschap_masterkey(u_int8_t *password_hash2, u_int8_t *ntresponse,
u_int8_t *masterkey)
{
u_int8_t md[SHA_DIGEST_LENGTH];
u_int mdlen;
EVP_MD_CTX *ctx;
static u_int8_t magic1[27] = {
0x54, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74,
0x68, 0x65, 0x20, 0x4d, 0x50, 0x50, 0x45, 0x20, 0x4d,
0x61, 0x73, 0x74, 0x65, 0x72, 0x20, 0x4b, 0x65, 0x79
};
ctx = EVP_MD_CTX_new();
EVP_DigestInit_ex(ctx, EVP_sha1(), NULL);
EVP_DigestUpdate(ctx, password_hash2, MSCHAP_HASH_SZ);
EVP_DigestUpdate(ctx, ntresponse, 24);
EVP_DigestUpdate(ctx, magic1, 27);
EVP_DigestFinal_ex(ctx, md, &mdlen);
EVP_MD_CTX_free(ctx);
memcpy(masterkey, md, 16);
}
void
mschap_asymetric_startkey(u_int8_t *masterkey, u_int8_t *sessionkey,
int sessionkeylen, int issend, int isserver)
{
EVP_MD_CTX *ctx;
u_int8_t md[SHA_DIGEST_LENGTH];
u_int mdlen;
u_int8_t *s;
static u_int8_t magic2[84] = {
0x4f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x69,
0x65, 0x6e, 0x74, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20,
0x74, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68,
0x65, 0x20, 0x73, 0x65, 0x6e, 0x64, 0x20, 0x6b, 0x65, 0x79,
0x3b, 0x20, 0x6f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73,
0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x73, 0x69, 0x64, 0x65,
0x2c, 0x20, 0x69, 0x74, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68,
0x65, 0x20, 0x72, 0x65, 0x63, 0x65, 0x69, 0x76, 0x65, 0x20,
0x6b, 0x65, 0x79, 0x2e
};
static u_int8_t magic3[84] = {
0x4f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x69,
0x65, 0x6e, 0x74, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20,
0x74, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68,
0x65, 0x20, 0x72, 0x65, 0x63, 0x65, 0x69, 0x76, 0x65, 0x20,
0x6b, 0x65, 0x79, 0x3b, 0x20, 0x6f, 0x6e, 0x20, 0x74, 0x68,
0x65, 0x20, 0x73, 0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x73,
0x69, 0x64, 0x65, 0x2c, 0x20, 0x69, 0x74, 0x20, 0x69, 0x73,
0x20, 0x74, 0x68, 0x65, 0x20, 0x73, 0x65, 0x6e, 0x64, 0x20,
0x6b, 0x65, 0x79, 0x2e
};
if (issend)
s = isserver ? magic3 : magic2;
else
s = isserver ? magic2 : magic3;
ctx = EVP_MD_CTX_new();
EVP_DigestInit_ex(ctx, EVP_sha1(), NULL);
EVP_DigestUpdate(ctx, masterkey, 16);
EVP_DigestUpdate(ctx, sha1_pad1, 40);
EVP_DigestUpdate(ctx, s, 84);
EVP_DigestUpdate(ctx, sha1_pad2, 40);
EVP_DigestFinal_ex(ctx, md, &mdlen);
EVP_MD_CTX_free(ctx);
memcpy(sessionkey, md, sessionkeylen);
}
void
mschap_msk(u_int8_t *password, int passwordlen,
u_int8_t *ntresponse, u_int8_t *msk)
{
u_int8_t password_hash[MSCHAP_HASH_SZ];
u_int8_t password_hash2[MSCHAP_HASH_SZ];
u_int8_t masterkey[MSCHAP_MASTERKEY_SZ];
u_int8_t sendkey[MSCHAP_MASTERKEY_SZ];
u_int8_t recvkey[MSCHAP_MASTERKEY_SZ];
mschap_ntpassword_hash(password, passwordlen, password_hash);
mschap_ntpassword_hash(password_hash, MSCHAP_HASH_SZ, password_hash2);
mschap_masterkey(password_hash2, ntresponse, masterkey);
mschap_asymetric_startkey(masterkey, recvkey, sizeof(recvkey), 0, 1);
mschap_asymetric_startkey(masterkey, sendkey, sizeof(sendkey), 1, 1);
/* 16 bytes receive key + 16 bytes send key + 32 bytes 0 padding */
bzero(msk, MSCHAP_MSK_SZ);
memcpy(msk, &recvkey, sizeof(recvkey));
memcpy(msk + sizeof(recvkey), &sendkey, sizeof(sendkey));
}
void
mschap_radiuskey(u_int8_t *plain, const u_int8_t *encrypted,
const u_int8_t *authenticator, const u_int8_t *secret)
{
EVP_MD_CTX *ctx;
u_int8_t b[MD5_DIGEST_LENGTH], p[32];
u_int i, mdlen;
ctx = EVP_MD_CTX_new();
EVP_DigestInit_ex(ctx, EVP_md5(), NULL);
EVP_DigestUpdate(ctx, secret, strlen(secret));
EVP_DigestUpdate(ctx, authenticator, 16);
EVP_DigestUpdate(ctx, encrypted, 2);
EVP_DigestFinal_ex(ctx, b, &mdlen);
for (i = 0; i < mdlen; i++) {
p[i] = b[i] ^ encrypted[i+2];
}
EVP_DigestInit_ex(ctx, EVP_md5(), NULL);
EVP_DigestUpdate(ctx, secret, strlen(secret));
EVP_DigestUpdate(ctx, encrypted + 2, mdlen);
EVP_DigestFinal_ex(ctx, b, &mdlen);
EVP_MD_CTX_free(ctx);
for (i = 0; i < mdlen; i++) {
p[i+16] = b[i] ^ encrypted[i+18];
}
memcpy(plain, p+1, 16);
}
|
