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);
EVP_DigestInit(&ctx, EVP_sha1());
EVP_DigestUpdate(&ctx, password_hash2, sizeof(password_hash2));
EVP_DigestUpdate(&ctx, ntresponse, 24);
EVP_DigestUpdate(&ctx, magic1, 39);
EVP_DigestFinal(&ctx, md, &mdlen);
mschap_challenge_hash(peer_challenge, auth_challenge,
username, usernamelen, challenge);
EVP_DigestInit(&ctx, EVP_sha1());
EVP_DigestUpdate(&ctx, md, sizeof(md));
EVP_DigestUpdate(&ctx, challenge, sizeof(challenge));
EVP_DigestUpdate(&ctx, magic2, 41);
EVP_DigestFinal(&ctx, md, &mdlen);
/*
* 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_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_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);
}
static void
mschapv2_authenticate(chap *_this, int id, char *username, u_char *challenge,
int lchallenge, u_char *response)
{
int i, rval, passlen, lpkt;
u_char *pkt;
char password[MAX_PASSWORD_LENGTH * 2], ntresponse[24];
#ifdef USE_NPPPD_MPPE
char pwdhash[16], pwdhashhash[16];
#endif
CHAP_DBG((_this, LOG_DEBUG, "%s()", __func__));
pkt = ppp_packetbuf(_this->ppp, PPP_PROTO_CHAP) + HEADERLEN;
lpkt = _this->ppp->mru - HEADERLEN;
passlen = sizeof(password) / 2;
rval = npppd_get_user_password(_this->ppp->pppd, _this->ppp, username,
password, &passlen);
if (rval != 0) {
switch (rval) {
case 1:
chap_log(_this, LOG_INFO,
"username=\"%s\" user unknown", username);
break;
default:
chap_log(_this, LOG_ERR,
"username=\"%s\" generic error", username);
break;
}
goto auth_failed;
}
/* Convert the string charset from ASCII to UTF16-LE */
passlen = strlen(password);
for (i = passlen - 1; i >= 0; i--) {
password[i*2] = password[i];
password[i*2+1] = 0;
}
mschap_nt_response(challenge, response, username, strlen(username),
password, passlen * 2, ntresponse);
if (memcmp(ntresponse, response + 24, 24) != 0) {
chap_log(_this, LOG_INFO,
"username=\"%s\" password mismatch.", username);
goto auth_failed;
}
/*
* Authentication succeed
*/
CHAP_DBG((_this, LOG_DEBUG, "%s() OK", __func__));
mschap_auth_response(password, passlen * 2, ntresponse,
challenge, response, username, strlen(username), pkt);
lpkt = 42;
#ifdef USE_NPPPD_MPPE
if (_this->ppp->mppe.enabled != 0) {
mschap_ntpassword_hash(password, passlen * 2, pwdhash);
mschap_ntpassword_hash(pwdhash, sizeof(pwdhash), pwdhashhash);
mschap_masterkey(pwdhashhash, ntresponse,
_this->ppp->mppe.master_key);
mschap_asymetric_startkey(_this->ppp->mppe.master_key,
_this->ppp->mppe.recv.master_key, MPPE_KEYLEN, 0, 1);
mschap_asymetric_startkey(_this->ppp->mppe.master_key,
_this->ppp->mppe.send.master_key, MPPE_KEYLEN, 1, 1);
}
#endif
chap_response(_this, 1, pkt, lpkt);
return;
auth_failed:
/* No extra information */
mschapv2_send_error(_this, ERROR_AUTHENTICATION_FAILURE, 0);
return;
}