/*
 * chap_ms.c - Microsoft MS-CHAP compatible implementation.
 *
 * 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.
 *
 * 3. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * 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
 */

/*
 * Modifications by Frank Cusack, frank@google.com, March 2002.
 *
 *   Implemented MS-CHAPv2 functionality, heavily based on sample
 *   implementation in RFC 2759.  Implemented MPPE functionality,
 *   heavily based on sample implementation in RFC 3079.
 *
 * Copyright (c) 2002 Google, Inc.  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.
 *
 * 3. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT && MSCHAP_SUPPORT  /* don't build if not configured for use in lwipopts.h */

#if 0 /* UNUSED */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#endif /* UNUSED */

#include "netif/ppp/ppp_impl.h"

#include "netif/ppp/chap-new.h"
#include "netif/ppp/chap_ms.h"
#include "netif/ppp/pppcrypt.h"
#include "netif/ppp/magic.h"
#if MPPE_SUPPORT
#include "netif/ppp/mppe.h" /* For mppe_sha1_pad*, mppe_set_key() */
#endif /* MPPE_SUPPORT */

#define SHA1_SIGNATURE_SIZE    20
#define MD4_SIGNATURE_SIZE    16    /* 16 bytes in a MD4 message digest */
#define MAX_NT_PASSWORD        256    /* Max (Unicode) chars in an NT pass */

#define MS_CHAP_RESPONSE_LEN    49    /* Response length for MS-CHAP */
#define MS_CHAP2_RESPONSE_LEN    49    /* Response length for MS-CHAPv2 */
#define MS_AUTH_RESPONSE_LENGTH    40    /* MS-CHAPv2 authenticator response, */
                    /* as ASCII */

/* Error codes for MS-CHAP failure messages. */
#define MS_CHAP_ERROR_RESTRICTED_LOGON_HOURS    646
#define MS_CHAP_ERROR_ACCT_DISABLED        647
#define MS_CHAP_ERROR_PASSWD_EXPIRED        648
#define MS_CHAP_ERROR_NO_DIALIN_PERMISSION    649
#define MS_CHAP_ERROR_AUTHENTICATION_FAILURE    691
#define MS_CHAP_ERROR_CHANGING_PASSWORD        709

/*
 * Offsets within the response field for MS-CHAP
 */
#define MS_CHAP_LANMANRESP    0
#define MS_CHAP_LANMANRESP_LEN    24
#define MS_CHAP_NTRESP        24
#define MS_CHAP_NTRESP_LEN    24
#define MS_CHAP_USENT        48

/*
 * Offsets within the response field for MS-CHAP2
 */
#define MS_CHAP2_PEER_CHALLENGE    0
#define MS_CHAP2_PEER_CHAL_LEN    16
#define MS_CHAP2_RESERVED_LEN    8
#define MS_CHAP2_NTRESP        24
#define MS_CHAP2_NTRESP_LEN    24
#define MS_CHAP2_FLAGS        48

#if MPPE_SUPPORT
#if 0 /* UNUSED */
/* These values are the RADIUS attribute values--see RFC 2548. */
#define MPPE_ENC_POL_ENC_ALLOWED 1
#define MPPE_ENC_POL_ENC_REQUIRED 2
#define MPPE_ENC_TYPES_RC4_40 2
#define MPPE_ENC_TYPES_RC4_128 4

/* used by plugins (using above values) */
extern void set_mppe_enc_types(int, int);
#endif /* UNUSED */
#endif /* MPPE_SUPPORT */

/* Are we the authenticator or authenticatee?  For MS-CHAPv2 key derivation. */
#define MS_CHAP2_AUTHENTICATEE 0
#define MS_CHAP2_AUTHENTICATOR 1

static void    ascii2unicode (const char[], int, u_char[]);
static void    NTPasswordHash (u_char *, int, u_char[MD4_SIGNATURE_SIZE]);
static void    ChallengeResponse (const u_char *, const u_char *, u_char[24]);
static void    ChallengeHash (const u_char[16], const u_char *, const char *, u_char[8]);
static void    ChapMS_NT (const u_char *, const char *, int, u_char[24]);
static void    ChapMS2_NT (const u_char *, const u_char[16], const char *, const char *, int,
                u_char[24]);
static void    GenerateAuthenticatorResponsePlain
            (const char*, int, u_char[24], const u_char[16], const u_char *,
                 const char *, u_char[41]);
#ifdef MSLANMAN
static void    ChapMS_LANMan (u_char *, char *, int, u_char *);
#endif

static void GenerateAuthenticatorResponse(const u_char PasswordHashHash[MD4_SIGNATURE_SIZE],
            u_char NTResponse[24], const u_char PeerChallenge[16],
            const u_char *rchallenge, const char *username,
            u_char authResponse[MS_AUTH_RESPONSE_LENGTH+1]);

#if MPPE_SUPPORT
static void    Set_Start_Key (ppp_pcb *pcb, const u_char *, const char *, int);
static void    SetMasterKeys (ppp_pcb *pcb, const char *, int, u_char[24], int);
#endif /* MPPE_SUPPORT */

static void ChapMS (ppp_pcb *pcb, const u_char *, const char *, int, u_char *);
static void ChapMS2 (ppp_pcb *pcb, const u_char *, const u_char *, const char *, const char *, int,
          u_char *, u_char[MS_AUTH_RESPONSE_LENGTH+1], int);

#ifdef MSLANMAN
bool    ms_lanman = 0;        /* Use LanMan password instead of NT */
                  /* Has meaning only with MS-CHAP challenges */
#endif

#if MPPE_SUPPORT
#ifdef DEBUGMPPEKEY
/* For MPPE debug */
/* Use "[]|}{?/><,`!2&&(" (sans quotes) for RFC 3079 MS-CHAPv2 test value */
static char *mschap_challenge = NULL;
/* Use "!@\#$%^&*()_+:3|~" (sans quotes, backslash is to escape #) for ... */
static char *mschap2_peer_challenge = NULL;
#endif

#include "netif/ppp/fsm.h"        /* Need to poke MPPE options */
#include "netif/ppp/ccp.h"
#endif /* MPPE_SUPPORT */

#if PPP_OPTIONS
/*
 * Command-line options.
 */
static option_t chapms_option_list[] = {
#ifdef MSLANMAN
    { "ms-lanman", o_bool, &ms_lanman,
      "Use LanMan passwd when using MS-CHAP", 1 },
#endif
#ifdef DEBUGMPPEKEY
    { "mschap-challenge", o_string, &mschap_challenge,
      "specify CHAP challenge" },
    { "mschap2-peer-challenge", o_string, &mschap2_peer_challenge,
      "specify CHAP peer challenge" },
#endif
    { NULL }
};
#endif /* PPP_OPTIONS */

#if PPP_SERVER
/*
 * chapms_generate_challenge - generate a challenge for MS-CHAP.
 * For MS-CHAP the challenge length is fixed at 8 bytes.
 * The length goes in challenge[0] and the actual challenge starts
 * at challenge[1].
 */
static void chapms_generate_challenge(ppp_pcb *pcb, unsigned char *challenge) {
    LWIP_UNUSED_ARG(pcb);

    *challenge++ = 8;
#ifdef DEBUGMPPEKEY
    if (mschap_challenge && strlen(mschap_challenge) == 8)
        memcpy(challenge, mschap_challenge, 8);
    else
#endif
        magic_random_bytes(challenge, 8);
}

static void chapms2_generate_challenge(ppp_pcb *pcb, unsigned char *challenge) {
    LWIP_UNUSED_ARG(pcb);

    *challenge++ = 16;
#ifdef DEBUGMPPEKEY
    if (mschap_challenge && strlen(mschap_challenge) == 16)
        memcpy(challenge, mschap_challenge, 16);
    else
#endif
        magic_random_bytes(challenge, 16);
}

static int chapms_verify_response(ppp_pcb *pcb, int id, const char *name,
               const unsigned char *secret, int secret_len,
               const unsigned char *challenge, const unsigned char *response,
               char *message, int message_space) {
    unsigned char md[MS_CHAP_RESPONSE_LEN];
    int diff;
    int challenge_len, response_len;
    LWIP_UNUSED_ARG(id);
    LWIP_UNUSED_ARG(name);

    challenge_len = *challenge++;    /* skip length, is 8 */
    response_len = *response++;
    if (response_len != MS_CHAP_RESPONSE_LEN)
        goto bad;

#ifndef MSLANMAN
    if (!response[MS_CHAP_USENT]) {
        /* Should really propagate this into the error packet. */
        ppp_notice("Peer request for LANMAN auth not supported");
        goto bad;
    }
#endif

    /* Generate the expected response. */
    ChapMS(pcb, (const u_char *)challenge, (const char *)secret, secret_len, md);

#ifdef MSLANMAN
    /* Determine which part of response to verify against */
    if (!response[MS_CHAP_USENT])
        diff = memcmp(&response[MS_CHAP_LANMANRESP],
                  &md[MS_CHAP_LANMANRESP], MS_CHAP_LANMANRESP_LEN);
    else
#endif
        diff = memcmp(&response[MS_CHAP_NTRESP], &md[MS_CHAP_NTRESP],
                  MS_CHAP_NTRESP_LEN);

    if (diff == 0) {
        ppp_slprintf(message, message_space, "Access granted");
        return 1;
    }

 bad:
    /* See comments below for MS-CHAP V2 */
    ppp_slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0",
         challenge_len, challenge);
    return 0;
}

static int chapms2_verify_response(ppp_pcb *pcb, int id, const char *name,
            const unsigned char *secret, int secret_len,
            const unsigned char *challenge, const unsigned char *response,
            char *message, int message_space) {
    unsigned char md[MS_CHAP2_RESPONSE_LEN];
    char saresponse[MS_AUTH_RESPONSE_LENGTH+1];
    int challenge_len, response_len;
    LWIP_UNUSED_ARG(id);

    challenge_len = *challenge++;    /* skip length, is 16 */
    response_len = *response++;
    if (response_len != MS_CHAP2_RESPONSE_LEN)
        goto bad;    /* not even the right length */

    /* Generate the expected response and our mutual auth. */
    ChapMS2(pcb, (const u_char*)challenge, (const u_char*)&response[MS_CHAP2_PEER_CHALLENGE], name,
        (const char *)secret, secret_len, md,
        (unsigned char *)saresponse, MS_CHAP2_AUTHENTICATOR);

    /* compare MDs and send the appropriate status */
    /*
     * Per RFC 2759, success message must be formatted as
     *     "S=<auth_string> M=<message>"
     * where
     *     <auth_string> is the Authenticator Response (mutual auth)
     *     <message> is a text message
     *
     * However, some versions of Windows (win98 tested) do not know
     * about the M=<message> part (required per RFC 2759) and flag
     * it as an error (reported incorrectly as an encryption error
     * to the user).  Since the RFC requires it, and it can be
     * useful information, we supply it if the peer is a conforming
     * system.  Luckily (?), win98 sets the Flags field to 0x04
     * (contrary to RFC requirements) so we can use that to
     * distinguish between conforming and non-conforming systems.
     *
     * Special thanks to Alex Swiridov <say@real.kharkov.ua> for
     * help debugging this.
     */
    if (memcmp(&md[MS_CHAP2_NTRESP], &response[MS_CHAP2_NTRESP],
           MS_CHAP2_NTRESP_LEN) == 0) {
        if (response[MS_CHAP2_FLAGS])
            ppp_slprintf(message, message_space, "S=%s", saresponse);
        else
            ppp_slprintf(message, message_space, "S=%s M=%s",
                 saresponse, "Access granted");
        return 1;
    }

 bad:
    /*
     * Failure message must be formatted as
     *     "E=e R=r C=c V=v M=m"
     * where
     *     e = error code (we use 691, ERROR_AUTHENTICATION_FAILURE)
     *     r = retry (we use 1, ok to retry)
     *     c = challenge to use for next response, we reuse previous
     *     v = Change Password version supported, we use 0
     *     m = text message
     *
     * The M=m part is only for MS-CHAPv2.  Neither win2k nor
     * win98 (others untested) display the message to the user anyway.
     * They also both ignore the E=e code.
     *
     * Note that it's safe to reuse the same challenge as we don't
     * actually accept another response based on the error message
     * (and no clients try to resend a response anyway).
     *
     * Basically, this whole bit is useless code, even the small
     * implementation here is only because of overspecification.
     */
    ppp_slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0 M=%s",
         challenge_len, challenge, "Access denied");
    return 0;
}
#endif /* PPP_SERVER */

static void chapms_make_response(ppp_pcb *pcb, unsigned char *response, int id, const char *our_name,
             const unsigned char *challenge, const char *secret, int secret_len,
             unsigned char *private_) {
    LWIP_UNUSED_ARG(id);
    LWIP_UNUSED_ARG(our_name);
    LWIP_UNUSED_ARG(private_);
    challenge++;    /* skip length, should be 8 */
    *response++ = MS_CHAP_RESPONSE_LEN;
    ChapMS(pcb, challenge, secret, secret_len, response);
}

static void chapms2_make_response(ppp_pcb *pcb, unsigned char *response, int id, const char *our_name,
              const unsigned char *challenge, const char *secret, int secret_len,
              unsigned char *private_) {
    LWIP_UNUSED_ARG(id);
    challenge++;    /* skip length, should be 16 */
    *response++ = MS_CHAP2_RESPONSE_LEN;
    ChapMS2(pcb, challenge,
#ifdef DEBUGMPPEKEY
        mschap2_peer_challenge,
#else
        NULL,
#endif
        our_name, secret, secret_len, response, private_,
        MS_CHAP2_AUTHENTICATEE);
}

static int chapms2_check_success(ppp_pcb *pcb, unsigned char *msg, int len, unsigned char *private_) {
    LWIP_UNUSED_ARG(pcb);

    if ((len < MS_AUTH_RESPONSE_LENGTH + 2) ||
        strncmp((char *)msg, "S=", 2) != 0) {
        /* Packet does not start with "S=" */
        ppp_error("MS-CHAPv2 Success packet is badly formed.");
        return 0;
    }
    msg += 2;
    len -= 2;
    if (len < MS_AUTH_RESPONSE_LENGTH
        || memcmp(msg, private_, MS_AUTH_RESPONSE_LENGTH)) {
        /* Authenticator Response did not match expected. */
        ppp_error("MS-CHAPv2 mutual authentication failed.");
        return 0;
    }
    /* Authenticator Response matches. */
    msg += MS_AUTH_RESPONSE_LENGTH; /* Eat it */
    len -= MS_AUTH_RESPONSE_LENGTH;
    if ((len >= 3) && !strncmp((char *)msg, " M=", 3)) {
        msg += 3; /* Eat the delimiter */
    } else if (len) {
        /* Packet has extra text which does not begin " M=" */
        ppp_error("MS-CHAPv2 Success packet is badly formed.");
        return 0;
    }
    return 1;
}

static void chapms_handle_failure(ppp_pcb *pcb, unsigned char *inp, int len) {
    int err;
    const char *p;
    char msg[64];
    LWIP_UNUSED_ARG(pcb);

    /* We want a null-terminated string for strxxx(). */
    len = LWIP_MIN(len, 63);
    MEMCPY(msg, inp, len);
    msg[len] = 0;
    p = msg;

    /*
     * Deal with MS-CHAP formatted failure messages; just print the
     * M=<message> part (if any).  For MS-CHAP we're not really supposed
     * to use M=<message>, but it shouldn't hurt.  See
     * chapms[2]_verify_response.
     */
    if (!strncmp(p, "E=", 2))
        err = strtol(p+2, NULL, 10); /* Remember the error code. */
    else
        goto print_msg; /* Message is badly formatted. */

    if (len && ((p = strstr(p, " M=")) != NULL)) {
        /* M=<message> field found. */
        p += 3;
    } else {
        /* No M=<message>; use the error code. */
        switch (err) {
        case MS_CHAP_ERROR_RESTRICTED_LOGON_HOURS:
            p = "E=646 Restricted logon hours";
            break;

        case MS_CHAP_ERROR_ACCT_DISABLED:
            p = "E=647 Account disabled";
            break;

        case MS_CHAP_ERROR_PASSWD_EXPIRED:
            p = "E=648 Password expired";
            break;

        case MS_CHAP_ERROR_NO_DIALIN_PERMISSION:
            p = "E=649 No dialin permission";
            break;

        case MS_CHAP_ERROR_AUTHENTICATION_FAILURE:
            p = "E=691 Authentication failure";
            break;

        case MS_CHAP_ERROR_CHANGING_PASSWORD:
            /* Should never see this, we don't support Change Password. */
            p = "E=709 Error changing password";
            break;

        default:
            ppp_error("Unknown MS-CHAP authentication failure: %.*v",
                  len, inp);
            return;
        }
    }
print_msg:
    if (p != NULL)
        ppp_error("MS-CHAP authentication failed: %v", p);
}

static void ChallengeResponse(const u_char *challenge,
          const u_char PasswordHash[MD4_SIGNATURE_SIZE],
          u_char response[24]) {
    u_char    ZPasswordHash[21];
    lwip_des_context des;
    u_char des_key[8];

    BZERO(ZPasswordHash, sizeof(ZPasswordHash));
    MEMCPY(ZPasswordHash, PasswordHash, MD4_SIGNATURE_SIZE);

#if 0
    dbglog("ChallengeResponse - ZPasswordHash %.*B",
       sizeof(ZPasswordHash), ZPasswordHash);
#endif

    pppcrypt_56_to_64_bit_key(ZPasswordHash + 0, des_key);
    lwip_des_init(&des);
    lwip_des_setkey_enc(&des, des_key);
    lwip_des_crypt_ecb(&des, challenge, response +0);
    lwip_des_free(&des);

    pppcrypt_56_to_64_bit_key(ZPasswordHash + 7, des_key);
    lwip_des_init(&des);
    lwip_des_setkey_enc(&des, des_key);
    lwip_des_crypt_ecb(&des, challenge, response +8);
    lwip_des_free(&des);

    pppcrypt_56_to_64_bit_key(ZPasswordHash + 14, des_key);
    lwip_des_init(&des);
    lwip_des_setkey_enc(&des, des_key);
    lwip_des_crypt_ecb(&des, challenge, response +16);
    lwip_des_free(&des);

#if 0
    dbglog("ChallengeResponse - response %.24B", response);
#endif
}

static void ChallengeHash(const u_char PeerChallenge[16], const u_char *rchallenge,
          const char *username, u_char Challenge[8]) {
    lwip_sha1_context    sha1Context;
    u_char    sha1Hash[SHA1_SIGNATURE_SIZE];
    const char    *user;

    /* remove domain from "domain\username" */
    if ((user = strrchr(username, '\\')) != NULL)
    ++user;
    else
    user = username;

    lwip_sha1_init(&sha1Context);
    lwip_sha1_starts(&sha1Context);
    lwip_sha1_update(&sha1Context, PeerChallenge, 16);
    lwip_sha1_update(&sha1Context, rchallenge, 16);
    lwip_sha1_update(&sha1Context, (const unsigned char*)user, strlen(user));
    lwip_sha1_finish(&sha1Context, sha1Hash);
    lwip_sha1_free(&sha1Context);

    MEMCPY(Challenge, sha1Hash, 8);
}

/*
 * Convert the ASCII version of the password to Unicode.
 * This implicitly supports 8-bit ISO8859/1 characters.
 * This gives us the little-endian representation, which
 * is assumed by all M$ CHAP RFCs.  (Unicode byte ordering
 * is machine-dependent.)
 */
static void ascii2unicode(const char ascii[], int ascii_len, u_char unicode[]) {
    int i;

    BZERO(unicode, ascii_len * 2);
    for (i = 0; i < ascii_len; i++)
    unicode[i * 2] = (u_char) ascii[i];
}

static void NTPasswordHash(u_char *secret, int secret_len, u_char hash[MD4_SIGNATURE_SIZE]) {
    lwip_md4_context        md4Context;

    lwip_md4_init(&md4Context);
    lwip_md4_starts(&md4Context);
    lwip_md4_update(&md4Context, secret, secret_len);
    lwip_md4_finish(&md4Context, hash);
    lwip_md4_free(&md4Context);
}

static void ChapMS_NT(const u_char *rchallenge, const char *secret, int secret_len,
      u_char NTResponse[24]) {
    u_char    unicodePassword[MAX_NT_PASSWORD * 2];
    u_char    PasswordHash[MD4_SIGNATURE_SIZE];

    /* Hash the Unicode version of the secret (== password). */
    ascii2unicode(secret, secret_len, unicodePassword);
    NTPasswordHash(unicodePassword, secret_len * 2, PasswordHash);

    ChallengeResponse(rchallenge, PasswordHash, NTResponse);
}

static void ChapMS2_NT(const u_char *rchallenge, const u_char PeerChallenge[16], const char *username,
       const char *secret, int secret_len, u_char NTResponse[24]) {
    u_char    unicodePassword[MAX_NT_PASSWORD * 2];
    u_char    PasswordHash[MD4_SIGNATURE_SIZE];
    u_char    Challenge[8];

    ChallengeHash(PeerChallenge, rchallenge, username, Challenge);

    /* Hash the Unicode version of the secret (== password). */
    ascii2unicode(secret, secret_len, unicodePassword);
    NTPasswordHash(unicodePassword, secret_len * 2, PasswordHash);

    ChallengeResponse(Challenge, PasswordHash, NTResponse);
}

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

static void ChapMS_LANMan(u_char *rchallenge, char *secret, int secret_len,
          unsigned char *response) {
    int            i;
    u_char        UcasePassword[MAX_NT_PASSWORD]; /* max is actually 14 */
    u_char        PasswordHash[MD4_SIGNATURE_SIZE];
    lwip_des_context des;
    u_char des_key[8];

    /* LANMan password is case insensitive */
    BZERO(UcasePassword, sizeof(UcasePassword));
    for (i = 0; i < secret_len; i++)
       UcasePassword[i] = (u_char)toupper(secret[i]);

    pppcrypt_56_to_64_bit_key(UcasePassword +0, des_key);
    lwip_des_init(&des);
    lwip_des_setkey_enc(&des, des_key);
    lwip_des_crypt_ecb(&des, StdText, PasswordHash +0);
    lwip_des_free(&des);

    pppcrypt_56_to_64_bit_key(UcasePassword +7, des_key);
    lwip_des_init(&des);
    lwip_des_setkey_enc(&des, des_key);
    lwip_des_crypt_ecb(&des, StdText, PasswordHash +8);
    lwip_des_free(&des);

    ChallengeResponse(rchallenge, PasswordHash, &response[MS_CHAP_LANMANRESP]);
}
#endif


static void GenerateAuthenticatorResponse(const u_char PasswordHashHash[MD4_SIGNATURE_SIZE],
                  u_char NTResponse[24], const u_char PeerChallenge[16],
                  const u_char *rchallenge, const char *username,
                  u_char authResponse[MS_AUTH_RESPONSE_LENGTH+1]) {
    /*
     * "Magic" constants used in response generation, from RFC 2759.
     */
    static const u_char Magic1[39] = /* "Magic server to client signing constant" */
    { 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 const u_char Magic2[41] = /* "Pad to make it do more than one iteration" */
    { 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 };

    int        i;
    lwip_sha1_context    sha1Context;
    u_char    Digest[SHA1_SIGNATURE_SIZE];
    u_char    Challenge[8];

    lwip_sha1_init(&sha1Context);
    lwip_sha1_starts(&sha1Context);
    lwip_sha1_update(&sha1Context, PasswordHashHash, MD4_SIGNATURE_SIZE);
    lwip_sha1_update(&sha1Context, NTResponse, 24);
    lwip_sha1_update(&sha1Context, Magic1, sizeof(Magic1));
    lwip_sha1_finish(&sha1Context, Digest);
    lwip_sha1_free(&sha1Context);

    ChallengeHash(PeerChallenge, rchallenge, username, Challenge);

    lwip_sha1_init(&sha1Context);
    lwip_sha1_starts(&sha1Context);
    lwip_sha1_update(&sha1Context, Digest, sizeof(Digest));
    lwip_sha1_update(&sha1Context, Challenge, sizeof(Challenge));
    lwip_sha1_update(&sha1Context, Magic2, sizeof(Magic2));
    lwip_sha1_finish(&sha1Context, Digest);
    lwip_sha1_free(&sha1Context);

    /* Convert to ASCII hex string. */
    for (i = 0; i < LWIP_MAX((MS_AUTH_RESPONSE_LENGTH / 2), (int)sizeof(Digest)); i++)
    sprintf((char *)&authResponse[i * 2], "%02X", Digest[i]);
}


static void GenerateAuthenticatorResponsePlain(
         const char *secret, int secret_len,
         u_char NTResponse[24], const u_char PeerChallenge[16],
         const u_char *rchallenge, const char *username,
         u_char authResponse[MS_AUTH_RESPONSE_LENGTH+1]) {
    u_char    unicodePassword[MAX_NT_PASSWORD * 2];
    u_char    PasswordHash[MD4_SIGNATURE_SIZE];
    u_char    PasswordHashHash[MD4_SIGNATURE_SIZE];

    /* Hash (x2) the Unicode version of the secret (== password). */
    ascii2unicode(secret, secret_len, unicodePassword);
    NTPasswordHash(unicodePassword, secret_len * 2, PasswordHash);
    NTPasswordHash(PasswordHash, sizeof(PasswordHash),
           PasswordHashHash);

    GenerateAuthenticatorResponse(PasswordHashHash, NTResponse, PeerChallenge,
                  rchallenge, username, authResponse);
}


#if MPPE_SUPPORT
/*
 * Set mppe_xxxx_key from MS-CHAP credentials. (see RFC 3079)
 */
static void Set_Start_Key(ppp_pcb *pcb, const u_char *rchallenge, const char *secret, int secret_len) {
    u_char    unicodePassword[MAX_NT_PASSWORD * 2];
    u_char    PasswordHash[MD4_SIGNATURE_SIZE];
    u_char    PasswordHashHash[MD4_SIGNATURE_SIZE];
    lwip_sha1_context    sha1Context;
    u_char    Digest[SHA1_SIGNATURE_SIZE];    /* >= MPPE_MAX_KEY_LEN */

    /* Hash (x2) the Unicode version of the secret (== password). */
    ascii2unicode(secret, secret_len, unicodePassword);
    NTPasswordHash(unicodePassword, secret_len * 2, PasswordHash);
    NTPasswordHash(PasswordHash, sizeof(PasswordHash), PasswordHashHash);

    lwip_sha1_init(&sha1Context);
    lwip_sha1_starts(&sha1Context);
    lwip_sha1_update(&sha1Context, PasswordHashHash, MD4_SIGNATURE_SIZE);
    lwip_sha1_update(&sha1Context, PasswordHashHash, MD4_SIGNATURE_SIZE);
    lwip_sha1_update(&sha1Context, rchallenge, 8);
    lwip_sha1_finish(&sha1Context, Digest);
    lwip_sha1_free(&sha1Context);

    /* Same key in both directions. */
    mppe_set_key(pcb, &pcb->mppe_comp, Digest);
    mppe_set_key(pcb, &pcb->mppe_decomp, Digest);

    pcb->mppe_keys_set = 1;
}

/*
 * Set mppe_xxxx_key from MS-CHAPv2 credentials. (see RFC 3079)
 */
static void SetMasterKeys(ppp_pcb *pcb, const char *secret, int secret_len, u_char NTResponse[24], int IsServer) {
    u_char    unicodePassword[MAX_NT_PASSWORD * 2];
    u_char    PasswordHash[MD4_SIGNATURE_SIZE];
    u_char    PasswordHashHash[MD4_SIGNATURE_SIZE];
    lwip_sha1_context    sha1Context;
    u_char    MasterKey[SHA1_SIGNATURE_SIZE];    /* >= MPPE_MAX_KEY_LEN */
    u_char    Digest[SHA1_SIGNATURE_SIZE];    /* >= MPPE_MAX_KEY_LEN */
    const u_char *s;

    /* "This is the MPPE Master Key" */
    static const u_char 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 };
    /* "On the client side, this is the send key; "
       "on the server side, it is the receive key." */
    static const u_char 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 };
    /* "On the client side, this is the receive key; "
       "on the server side, it is the send key." */
    static const u_char 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 };

    /* Hash (x2) the Unicode version of the secret (== password). */
    ascii2unicode(secret, secret_len, unicodePassword);
    NTPasswordHash(unicodePassword, secret_len * 2, PasswordHash);
    NTPasswordHash(PasswordHash, sizeof(PasswordHash), PasswordHashHash);

    lwip_sha1_init(&sha1Context);
    lwip_sha1_starts(&sha1Context);
    lwip_sha1_update(&sha1Context, PasswordHashHash, MD4_SIGNATURE_SIZE);
    lwip_sha1_update(&sha1Context, NTResponse, 24);
    lwip_sha1_update(&sha1Context, Magic1, sizeof(Magic1));
    lwip_sha1_finish(&sha1Context, MasterKey);
    lwip_sha1_free(&sha1Context);

    /*
     * generate send key
     */
    if (IsServer)
    s = Magic3;
    else
    s = Magic2;
    lwip_sha1_init(&sha1Context);
    lwip_sha1_starts(&sha1Context);
    lwip_sha1_update(&sha1Context, MasterKey, 16);
    lwip_sha1_update(&sha1Context, mppe_sha1_pad1, SHA1_PAD_SIZE);
    lwip_sha1_update(&sha1Context, s, 84);
    lwip_sha1_update(&sha1Context, mppe_sha1_pad2, SHA1_PAD_SIZE);
    lwip_sha1_finish(&sha1Context, Digest);
    lwip_sha1_free(&sha1Context);

    mppe_set_key(pcb, &pcb->mppe_comp, Digest);

    /*
     * generate recv key
     */
    if (IsServer)
    s = Magic2;
    else
    s = Magic3;
    lwip_sha1_init(&sha1Context);
    lwip_sha1_starts(&sha1Context);
    lwip_sha1_update(&sha1Context, MasterKey, 16);
    lwip_sha1_update(&sha1Context, mppe_sha1_pad1, SHA1_PAD_SIZE);
    lwip_sha1_update(&sha1Context, s, 84);
    lwip_sha1_update(&sha1Context, mppe_sha1_pad2, SHA1_PAD_SIZE);
    lwip_sha1_finish(&sha1Context, Digest);
    lwip_sha1_free(&sha1Context);

    mppe_set_key(pcb, &pcb->mppe_decomp, Digest);

    pcb->mppe_keys_set = 1;
}

#endif /* MPPE_SUPPORT */


static void ChapMS(ppp_pcb *pcb, const u_char *rchallenge, const char *secret, int secret_len,
       unsigned char *response) {
#if !MPPE_SUPPORT
    LWIP_UNUSED_ARG(pcb);
#endif /* !MPPE_SUPPORT */
    BZERO(response, MS_CHAP_RESPONSE_LEN);

    ChapMS_NT(rchallenge, secret, secret_len, &response[MS_CHAP_NTRESP]);

#ifdef MSLANMAN
    ChapMS_LANMan(rchallenge, secret, secret_len,
          &response[MS_CHAP_LANMANRESP]);

    /* preferred method is set by option  */
    response[MS_CHAP_USENT] = !ms_lanman;
#else
    response[MS_CHAP_USENT] = 1;
#endif

#if MPPE_SUPPORT
    Set_Start_Key(pcb, rchallenge, secret, secret_len);
#endif /* MPPE_SUPPORT */
}


/*
 * If PeerChallenge is NULL, one is generated and the PeerChallenge
 * field of response is filled in.  Call this way when generating a response.
 * If PeerChallenge is supplied, it is copied into the PeerChallenge field.
 * Call this way when verifying a response (or debugging).
 * Do not call with PeerChallenge = response.
 *
 * The PeerChallenge field of response is then used for calculation of the
 * Authenticator Response.
 */
static void ChapMS2(ppp_pcb *pcb, const u_char *rchallenge, const u_char *PeerChallenge,
    const char *user, const char *secret, int secret_len, unsigned char *response,
    u_char authResponse[], int authenticator) {
    /* ARGSUSED */
    LWIP_UNUSED_ARG(authenticator);
#if !MPPE_SUPPORT
    LWIP_UNUSED_ARG(pcb);
#endif /* !MPPE_SUPPORT */

    BZERO(response, MS_CHAP2_RESPONSE_LEN);

    /* Generate the Peer-Challenge if requested, or copy it if supplied. */
    if (!PeerChallenge)
    magic_random_bytes(&response[MS_CHAP2_PEER_CHALLENGE], MS_CHAP2_PEER_CHAL_LEN);
    else
    MEMCPY(&response[MS_CHAP2_PEER_CHALLENGE], PeerChallenge,
          MS_CHAP2_PEER_CHAL_LEN);

    /* Generate the NT-Response */
    ChapMS2_NT(rchallenge, &response[MS_CHAP2_PEER_CHALLENGE], user,
           secret, secret_len, &response[MS_CHAP2_NTRESP]);

    /* Generate the Authenticator Response. */
    GenerateAuthenticatorResponsePlain(secret, secret_len,
                       &response[MS_CHAP2_NTRESP],
                       &response[MS_CHAP2_PEER_CHALLENGE],
                       rchallenge, user, authResponse);

#if MPPE_SUPPORT
    SetMasterKeys(pcb, secret, secret_len,
          &response[MS_CHAP2_NTRESP], authenticator);
#endif /* MPPE_SUPPORT */
}

#if 0 /* UNUSED */
#if MPPE_SUPPORT
/*
 * Set MPPE options from plugins.
 */
void set_mppe_enc_types(int policy, int types) {
    /* Early exit for unknown policies. */
    if (policy != MPPE_ENC_POL_ENC_ALLOWED ||
    policy != MPPE_ENC_POL_ENC_REQUIRED)
    return;

    /* Don't modify MPPE if it's optional and wasn't already configured. */
    if (policy == MPPE_ENC_POL_ENC_ALLOWED && !ccp_wantoptions[0].mppe)
    return;

    /*
     * Disable undesirable encryption types.  Note that we don't ENABLE
     * any encryption types, to avoid overriding manual configuration.
     */
    switch(types) {
    case MPPE_ENC_TYPES_RC4_40:
        ccp_wantoptions[0].mppe &= ~MPPE_OPT_128;    /* disable 128-bit */
        break;
    case MPPE_ENC_TYPES_RC4_128:
        ccp_wantoptions[0].mppe &= ~MPPE_OPT_40;    /* disable 40-bit */
        break;
    default:
        break;
    }
}
#endif /* MPPE_SUPPORT */
#endif /* UNUSED */

const struct chap_digest_type chapms_digest = {
    CHAP_MICROSOFT,        /* code */
#if PPP_SERVER
    chapms_generate_challenge,
    chapms_verify_response,
#endif /* PPP_SERVER */
    chapms_make_response,
    NULL,            /* check_success */
    chapms_handle_failure,
};

const struct chap_digest_type chapms2_digest = {
    CHAP_MICROSOFT_V2,    /* code */
#if PPP_SERVER
    chapms2_generate_challenge,
    chapms2_verify_response,
#endif /* PPP_SERVER */
    chapms2_make_response,
    chapms2_check_success,
    chapms_handle_failure,
};

#endif /* PPP_SUPPORT && MSCHAP_SUPPORT */
