mschapv2.c

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/*
 * MSCHAPV2 (RFC 2759)
 * Copyright (c) 2004-2008, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "crypto/ms_funcs.h"
#include "mschapv2.h"

const u8 * mschapv2_remove_domain(const u8 *username, size_t *len)
{
        size_t i;

        /*
         * MSCHAPv2 does not include optional domain name in the
         * challenge-response calculation, so remove domain prefix
         * (if present).
         */

        for (i = 0; i < *len; i++) {
                if (username[i] == '\\') {
                        *len -= i + 1;
                        return username + i + 1;
                }
        }

        return username;
}


int mschapv2_derive_response(const u8 *identity, size_t identity_len,
                             const u8 *password, size_t password_len,
                             int pwhash,
                             const u8 *auth_challenge,
                             const u8 *peer_challenge,
                             u8 *nt_response, u8 *auth_response,
                             u8 *master_key)
{
        const u8 *username;
        size_t username_len;
        u8 password_hash[16], password_hash_hash[16];

        wpa_hexdump_ascii(MSG_DEBUG, "MSCHAPV2: Identity",
                          identity, identity_len);
        username_len = identity_len;
        username = mschapv2_remove_domain(identity, &username_len);
        wpa_hexdump_ascii(MSG_DEBUG, "MSCHAPV2: Username",
                          username, username_len);

        wpa_hexdump(MSG_DEBUG, "MSCHAPV2: auth_challenge",
                    auth_challenge, MSCHAPV2_CHAL_LEN);
        wpa_hexdump(MSG_DEBUG, "MSCHAPV2: peer_challenge",
                    peer_challenge, MSCHAPV2_CHAL_LEN);
        wpa_hexdump_ascii(MSG_DEBUG, "MSCHAPV2: username",
                          username, username_len);
        /* Authenticator response is not really needed yet, but calculate it
         * here so that challenges need not be saved. */
        if (pwhash) {
                wpa_hexdump_key(MSG_DEBUG, "MSCHAPV2: password hash",
                                password, password_len);
                generate_nt_response_pwhash(auth_challenge, peer_challenge,
                                            username, username_len,
                                            password, nt_response);
                generate_authenticator_response_pwhash(
                        password, peer_challenge, auth_challenge,
                        username, username_len, nt_response, auth_response);
        } else {
                wpa_hexdump_ascii_key(MSG_DEBUG, "MSCHAPV2: password",
                                      password, password_len);
                generate_nt_response(auth_challenge, peer_challenge,
                                     username, username_len,
                                     password, password_len, nt_response);
                generate_authenticator_response(password, password_len,
                                                peer_challenge, auth_challenge,
                                                username, username_len,
                                                nt_response, auth_response);
        }
        wpa_hexdump(MSG_DEBUG, "MSCHAPV2: NT Response",
                    nt_response, MSCHAPV2_NT_RESPONSE_LEN);
        wpa_hexdump(MSG_DEBUG, "MSCHAPV2: Auth Response",
                    auth_response, MSCHAPV2_AUTH_RESPONSE_LEN);

        /* Generate master_key here since we have the needed data available. */
        if (pwhash) {
                if (hash_nt_password_hash(password, password_hash_hash))
                        return -1;
        } else {
                if (nt_password_hash(password, password_len, password_hash) ||
                    hash_nt_password_hash(password_hash, password_hash_hash))
                        return -1;
        }
        get_master_key(password_hash_hash, nt_response, master_key);
        wpa_hexdump_key(MSG_DEBUG, "MSCHAPV2: Master Key",
                        master_key, MSCHAPV2_MASTER_KEY_LEN);

        return 0;
}


int mschapv2_verify_auth_response(const u8 *auth_response,
                                  const u8 *buf, size_t buf_len)
{
        u8 recv_response[MSCHAPV2_AUTH_RESPONSE_LEN];
        if (buf_len < 2 + 2 * MSCHAPV2_AUTH_RESPONSE_LEN ||
            buf[0] != 'S' || buf[1] != '=' ||
            hexstr2bin((char *) (buf + 2), recv_response,
                       MSCHAPV2_AUTH_RESPONSE_LEN) ||
            os_memcmp(auth_response, recv_response,
                      MSCHAPV2_AUTH_RESPONSE_LEN) != 0)
                return -1;
        return 0;
}