/*-
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 <config.h>

RCSID("$Id$");

#if     defined(AUTHENTICATION) && defined(ENCRYPTION) && defined(DES_ENCRYPTION)
#include <arpa/telnet.h>
#include <stdio.h>
#ifdef  __STDC__
#include <stdlib.h>
#include <string.h>
#endif
#include <roken.h>
#ifdef SOCKS
#include <socks.h>
#endif

#include "encrypt.h"
#include "misc-proto.h"

#include "crypto-headers.h"

extern int encrypt_debug_mode;

#define CFB     0
#define OFB     1

#define NO_SEND_IV      1
#define NO_RECV_IV      2
#define NO_KEYID        4
#define IN_PROGRESS     (NO_SEND_IV|NO_RECV_IV|NO_KEYID)
#define SUCCESS         0
#define FAILED          -1


struct stinfo {
  DES_cblock    str_output;
  DES_cblock    str_feed;
  DES_cblock    str_iv;
  DES_cblock    str_ikey;
  DES_key_schedule str_sched;
  int           str_index;
  int           str_flagshift;
};

struct fb {
        DES_cblock krbdes_key;
        DES_key_schedule krbdes_sched;
        DES_cblock temp_feed;
        unsigned char fb_feed[64];
        int need_start;
        int state[2];
        int keyid[2];
        struct stinfo streams[2];
};

static struct fb fb[2];

struct keyidlist {
        char    *keyid;
        int     keyidlen;
        char    *key;
        int     keylen;
        int     flags;
} keyidlist [] = {
        { "\0", 1, 0, 0, 0 },           /* default key of zero */
        { 0, 0, 0, 0, 0 }
};

#define KEYFLAG_MASK    03

#define KEYFLAG_NOINIT  00
#define KEYFLAG_INIT    01
#define KEYFLAG_OK      02
#define KEYFLAG_BAD     03

#define KEYFLAG_SHIFT   2

#define SHIFT_VAL(a,b)  (KEYFLAG_SHIFT*((a)+((b)*2)))

#define FB64_IV         1
#define FB64_IV_OK      2
#define FB64_IV_BAD     3


void fb64_stream_iv (DES_cblock, struct stinfo *);
void fb64_init (struct fb *);
static int fb64_start (struct fb *, int, int);
int fb64_is (unsigned char *, int, struct fb *);
int fb64_reply (unsigned char *, int, struct fb *);
static void fb64_session (Session_Key *, int, struct fb *);
void fb64_stream_key (DES_cblock, struct stinfo *);
int fb64_keyid (int, unsigned char *, int *, struct fb *);
void fb64_printsub(unsigned char *, size_t ,
                   unsigned char *, size_t , char *);

void cfb64_init(int server)
{
        fb64_init(&fb[CFB]);
        fb[CFB].fb_feed[4] = ENCTYPE_DES_CFB64;
        fb[CFB].streams[0].str_flagshift = SHIFT_VAL(0, CFB);
        fb[CFB].streams[1].str_flagshift = SHIFT_VAL(1, CFB);
}


void ofb64_init(int server)
{
        fb64_init(&fb[OFB]);
        fb[OFB].fb_feed[4] = ENCTYPE_DES_OFB64;
        fb[CFB].streams[0].str_flagshift = SHIFT_VAL(0, OFB);
        fb[CFB].streams[1].str_flagshift = SHIFT_VAL(1, OFB);
}

void fb64_init(struct fb *fbp)
{
        memset(fbp,0, sizeof(*fbp));
        fbp->state[0] = fbp->state[1] = FAILED;
        fbp->fb_feed[0] = IAC;
        fbp->fb_feed[1] = SB;
        fbp->fb_feed[2] = TELOPT_ENCRYPT;
        fbp->fb_feed[3] = ENCRYPT_IS;
}

/*
 * Returns:
 *      -1: some error.  Negotiation is done, encryption not ready.
 *       0: Successful, initial negotiation all done.
 *       1: successful, negotiation not done yet.
 *       2: Not yet.  Other things (like getting the key from
 *          Kerberos) have to happen before we can continue.
 */
int cfb64_start(int dir, int server)
{
        return(fb64_start(&fb[CFB], dir, server));
}

int ofb64_start(int dir, int server)
{
        return(fb64_start(&fb[OFB], dir, server));
}

static int fb64_start(struct fb *fbp, int dir, int server)
{
        int x;
        unsigned char *p;
        int state;

        switch (dir) {
        case DIR_DECRYPT:
                /*
                 * This is simply a request to have the other side
                 * start output (our input).  He will negotiate an
                 * IV so we need not look for it.
                 */
                state = fbp->state[dir-1];
                if (state == FAILED)
                        state = IN_PROGRESS;
                break;

        case DIR_ENCRYPT:
                state = fbp->state[dir-1];
                if (state == FAILED)
                        state = IN_PROGRESS;
                else if ((state & NO_SEND_IV) == 0) {
                        break;
                }

                if (!VALIDKEY(fbp->krbdes_key)) {
                        fbp->need_start = 1;
                        break;
                }

                state &= ~NO_SEND_IV;
                state |= NO_RECV_IV;
                if (encrypt_debug_mode)
                        printf("Creating new feed\r\n");
                /*
                 * Create a random feed and send it over.
                 */
                do {
                    if (RAND_bytes(fbp->temp_feed,
                                   sizeof(*fbp->temp_feed)) != 1)
                        abort();
                    DES_set_odd_parity(&fbp->temp_feed);
                } while(DES_is_weak_key(&fbp->temp_feed));

                p = fbp->fb_feed + 3;
                *p++ = ENCRYPT_IS;
                p++;
                *p++ = FB64_IV;
                for (x = 0; x < sizeof(DES_cblock); ++x) {
                        if ((*p++ = fbp->temp_feed[x]) == IAC)
                                *p++ = IAC;
                }
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
                telnet_net_write(fbp->fb_feed, p - fbp->fb_feed);
                break;
        default:
                return(FAILED);
        }
        return(fbp->state[dir-1] = state);
}

/*
 * Returns:
 *      -1: some error.  Negotiation is done, encryption not ready.
 *       0: Successful, initial negotiation all done.
 *       1: successful, negotiation not done yet.
 */

int cfb64_is(unsigned char *data, int cnt)
{
        return(fb64_is(data, cnt, &fb[CFB]));
}

int ofb64_is(unsigned char *data, int cnt)
{
        return(fb64_is(data, cnt, &fb[OFB]));
}


int fb64_is(unsigned char *data, int cnt, struct fb *fbp)
{
        unsigned char *p;
        int state = fbp->state[DIR_DECRYPT-1];

        if (cnt-- < 1)
                goto failure;

        switch (*data++) {
        case FB64_IV:
                if (cnt != sizeof(DES_cblock)) {
                        if (encrypt_debug_mode)
                                printf("CFB64: initial vector failed on size\r\n");
                        state = FAILED;
                        goto failure;
                }

                if (encrypt_debug_mode)
                        printf("CFB64: initial vector received\r\n");

                if (encrypt_debug_mode)
                        printf("Initializing Decrypt stream\r\n");

                fb64_stream_iv(data, &fbp->streams[DIR_DECRYPT-1]);

                p = fbp->fb_feed + 3;
                *p++ = ENCRYPT_REPLY;
                p++;
                *p++ = FB64_IV_OK;
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
                telnet_net_write(fbp->fb_feed, p - fbp->fb_feed);

                state = fbp->state[DIR_DECRYPT-1] = IN_PROGRESS;
                break;

        default:
                if (encrypt_debug_mode) {
                        printf("Unknown option type: %d\r\n", *(data-1));
                        printd(data, cnt);
                        printf("\r\n");
                }
                /* FALL THROUGH */
        failure:
                /*
                 * We failed.  Send an FB64_IV_BAD option
                 * to the other side so it will know that
                 * things failed.
                 */
                p = fbp->fb_feed + 3;
                *p++ = ENCRYPT_REPLY;
                p++;
                *p++ = FB64_IV_BAD;
                *p++ = IAC;
                *p++ = SE;
                printsub('>', &fbp->fb_feed[2], p - &fbp->fb_feed[2]);
                telnet_net_write(fbp->fb_feed, p - fbp->fb_feed);

                break;
        }
        return(fbp->state[DIR_DECRYPT-1] = state);
}

/*
 * Returns:
 *      -1: some error.  Negotiation is done, encryption not ready.
 *       0: Successful, initial negotiation all done.
 *       1: successful, negotiation not done yet.
 */

int cfb64_reply(unsigned char *data, int cnt)
{
        return(fb64_reply(data, cnt, &fb[CFB]));
}

int ofb64_reply(unsigned char *data, int cnt)
{
        return(fb64_reply(data, cnt, &fb[OFB]));
}


int fb64_reply(unsigned char *data, int cnt, struct fb *fbp)
{
        int state = fbp->state[DIR_ENCRYPT-1];

        if (cnt-- < 1)
                goto failure;

        switch (*data++) {
        case FB64_IV_OK:
                fb64_stream_iv(fbp->temp_feed, &fbp->streams[DIR_ENCRYPT-1]);
                if (state == FAILED)
                        state = IN_PROGRESS;
                state &= ~NO_RECV_IV;
                encrypt_send_keyid(DIR_ENCRYPT, (unsigned char *)"\0", 1, 1);
                break;

        case FB64_IV_BAD:
                memset(fbp->temp_feed, 0, sizeof(DES_cblock));
                fb64_stream_iv(fbp->temp_feed, &fbp->streams[DIR_ENCRYPT-1]);
                state = FAILED;
                break;

        default:
                if (encrypt_debug_mode) {
                        printf("Unknown option type: %d\r\n", data[-1]);
                        printd(data, cnt);
                        printf("\r\n");
                }
                /* FALL THROUGH */
        failure:
                state = FAILED;
                break;
        }
        return(fbp->state[DIR_ENCRYPT-1] = state);
}

void cfb64_session(Session_Key *key, int server)
{
        fb64_session(key, server, &fb[CFB]);
}

void ofb64_session(Session_Key *key, int server)
{
        fb64_session(key, server, &fb[OFB]);
}

static void fb64_session(Session_Key *key, int server, struct fb *fbp)
{

        if (!key || key->type != SK_DES) {
                if (encrypt_debug_mode)
                        printf("Can't set krbdes's session key (%d != %d)\r\n",
                                key ? key->type : -1, SK_DES);
                return;
        }
        memcpy(fbp->krbdes_key, key->data, sizeof(DES_cblock));

        fb64_stream_key(fbp->krbdes_key, &fbp->streams[DIR_ENCRYPT-1]);
        fb64_stream_key(fbp->krbdes_key, &fbp->streams[DIR_DECRYPT-1]);

        RAND_seed(key->data, key->length);

        DES_set_key_checked((DES_cblock *)&fbp->krbdes_key,
                            &fbp->krbdes_sched);
        /*
         * Now look to see if krbdes_start() was waiting for the key to
         * show up.  If so, go ahead an call it now that we have the key.
         */
        if (fbp->need_start) {
                fbp->need_start = 0;
                fb64_start(fbp, DIR_ENCRYPT, server);
        }
}

/*
 * We only accept a keyid of 0.  If we get a keyid of
 * 0, then mark the state as SUCCESS.
 */

int cfb64_keyid(int dir, unsigned char *kp, int *lenp)
{
        return(fb64_keyid(dir, kp, lenp, &fb[CFB]));
}

int ofb64_keyid(int dir, unsigned char *kp, int *lenp)
{
        return(fb64_keyid(dir, kp, lenp, &fb[OFB]));
}

int fb64_keyid(int dir, unsigned char *kp, int *lenp, struct fb *fbp)
{
        int state = fbp->state[dir-1];

        if (*lenp != 1 || (*kp != '\0')) {
                *lenp = 0;
                return(state);
        }

        if (state == FAILED)
                state = IN_PROGRESS;

        state &= ~NO_KEYID;

        return(fbp->state[dir-1] = state);
}

void fb64_printsub(unsigned char *data, size_t cnt,
                   unsigned char *buf, size_t buflen, char *type)
{
        char lbuf[32];
        int i;
        char *cp;

        buf[buflen-1] = '\0';           /* make sure it's NULL terminated */
        buflen -= 1;

        switch(data[2]) {
        case FB64_IV:
                snprintf(lbuf, sizeof(lbuf), "%s_IV", type);
                cp = lbuf;
                goto common;

        case FB64_IV_OK:
                snprintf(lbuf, sizeof(lbuf), "%s_IV_OK", type);
                cp = lbuf;
                goto common;

        case FB64_IV_BAD:
                snprintf(lbuf, sizeof(lbuf), "%s_IV_BAD", type);
                cp = lbuf;
                goto common;

        default:
                snprintf(lbuf, sizeof(lbuf), " %d (unknown)", data[2]);
                cp = lbuf;
        common:
                for (; (buflen > 0) && (*buf = *cp++); buf++)
                        buflen--;
                for (i = 3; i < cnt; i++) {
                        snprintf(lbuf, sizeof(lbuf), " %d", data[i]);
                        for (cp = lbuf; (buflen > 0) && (*buf = *cp++); buf++)
                                buflen--;
                }
                break;
        }
}

void cfb64_printsub(unsigned char *data, size_t cnt,
                    unsigned char *buf, size_t buflen)
{
        fb64_printsub(data, cnt, buf, buflen, "CFB64");
}

void ofb64_printsub(unsigned char *data, size_t cnt,
                    unsigned char *buf, size_t buflen)
{
        fb64_printsub(data, cnt, buf, buflen, "OFB64");
}

void fb64_stream_iv(DES_cblock seed, struct stinfo *stp)
{

        memcpy(stp->str_iv, seed,sizeof(DES_cblock));
        memcpy(stp->str_output, seed, sizeof(DES_cblock));

        DES_set_key_checked(&stp->str_ikey, &stp->str_sched);

        stp->str_index = sizeof(DES_cblock);
}

void fb64_stream_key(DES_cblock key, struct stinfo *stp)
{
        memcpy(stp->str_ikey, key, sizeof(DES_cblock));
        DES_set_key_checked((DES_cblock*)key, &stp->str_sched);

        memcpy(stp->str_output, stp->str_iv, sizeof(DES_cblock));

        stp->str_index = sizeof(DES_cblock);
}

/*
 * DES 64 bit Cipher Feedback
 *
 *     key --->+-----+
 *          +->| DES |--+
 *          |  +-----+  |
 *          |           v
 *  INPUT --(--------->(+)+---> DATA
 *          |             |
 *          +-------------+
 *
 *
 * Given:
 *      iV: Initial vector, 64 bits (8 bytes) long.
 *      Dn: the nth chunk of 64 bits (8 bytes) of data to encrypt (decrypt).
 *      On: the nth chunk of 64 bits (8 bytes) of encrypted (decrypted) output.
 *
 *      V0 = DES(iV, key)
 *      On = Dn ^ Vn
 *      V(n+1) = DES(On, key)
 */

void cfb64_encrypt(unsigned char *s, int c)
{
        struct stinfo *stp = &fb[CFB].streams[DIR_ENCRYPT-1];
        int index;

        index = stp->str_index;
        while (c-- > 0) {
                if (index == sizeof(DES_cblock)) {
                        DES_cblock b;
                        DES_ecb_encrypt(&stp->str_output, &b,&stp->str_sched, 1);
                        memcpy(stp->str_feed, b, sizeof(DES_cblock));
                        index = 0;
                }

                /* On encryption, we store (feed ^ data) which is cypher */
                *s = stp->str_output[index] = (stp->str_feed[index] ^ *s);
                s++;
                index++;
        }
        stp->str_index = index;
}

int cfb64_decrypt(int data)
{
        struct stinfo *stp = &fb[CFB].streams[DIR_DECRYPT-1];
        int index;

        if (data == -1) {
                /*
                 * Back up one byte.  It is assumed that we will
                 * never back up more than one byte.  If we do, this
                 * may or may not work.
                 */
                if (stp->str_index)
                        --stp->str_index;
                return(0);
        }

        index = stp->str_index++;
        if (index == sizeof(DES_cblock)) {
                DES_cblock b;
                DES_ecb_encrypt(&stp->str_output,&b, &stp->str_sched, 1);
                memcpy(stp->str_feed, b, sizeof(DES_cblock));
                stp->str_index = 1;     /* Next time will be 1 */
                index = 0;              /* But now use 0 */
        }

        /* On decryption we store (data) which is cypher. */
        stp->str_output[index] = data;
        return(data ^ stp->str_feed[index]);
}

/*
 * DES 64 bit Output Feedback
 *
 * key --->+-----+
 *      +->| DES |--+
 *      |  +-----+  |
 *      +-----------+
 *                  v
 *  INPUT -------->(+) ----> DATA
 *
 * Given:
 *      iV: Initial vector, 64 bits (8 bytes) long.
 *      Dn: the nth chunk of 64 bits (8 bytes) of data to encrypt (decrypt).
 *      On: the nth chunk of 64 bits (8 bytes) of encrypted (decrypted) output.
 *
 *      V0 = DES(iV, key)
 *      V(n+1) = DES(Vn, key)
 *      On = Dn ^ Vn
 */

void ofb64_encrypt(unsigned char *s, int c)
{
        struct stinfo *stp = &fb[OFB].streams[DIR_ENCRYPT-1];
        int index;

        index = stp->str_index;
        while (c-- > 0) {
                if (index == sizeof(DES_cblock)) {
                        DES_cblock b;
                        DES_ecb_encrypt(&stp->str_feed,&b, &stp->str_sched, 1);
                        memcpy(stp->str_feed, b, sizeof(DES_cblock));
                        index = 0;
                }
                *s++ ^= stp->str_feed[index];
                index++;
        }
        stp->str_index = index;
}

int ofb64_decrypt(int data)
{
        struct stinfo *stp = &fb[OFB].streams[DIR_DECRYPT-1];
        int index;

        if (data == -1) {
                /*
                 * Back up one byte.  It is assumed that we will
                 * never back up more than one byte.  If we do, this
                 * may or may not work.
                 */
                if (stp->str_index)
                        --stp->str_index;
                return(0);
        }

        index = stp->str_index++;
        if (index == sizeof(DES_cblock)) {
                DES_cblock b;
                DES_ecb_encrypt(&stp->str_feed,&b,&stp->str_sched, 1);
                memcpy(stp->str_feed, b, sizeof(DES_cblock));
                stp->str_index = 1;     /* Next time will be 1 */
                index = 0;              /* But now use 0 */
        }

        return(data ^ stp->str_feed[index]);
}
#endif