src/libs/libtelnet/pk.c

   1 /*-
   2  * Copyright (c) 1991, 1993
   3  *      Dave Safford.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  */
  30
  31 #include <sys/cdefs.h>
  32
  33 __FBSDID("$FreeBSD: src/contrib/telnet/libtelnet/pk.c,v 1.10 2002/08/22 06:19:07 nsayer Exp $");
  34
  35 /* public key routines */
  36 /* functions:
  37         genkeys(char *public, char *secret)
  38         common_key(char *secret, char *public, desData *deskey)
  39         pk_encode(char *in, *out, DesData *deskey);
  40         pk_decode(char *in, *out, DesData *deskey);
  41       where
  42         char public[HEXKEYBYTES + 1];
  43         char secret[HEXKEYBYTES + 1];
  44  */
  45
  46 #include <sys/time.h>
  47 #include <openssl/des.h>
  48 #include <fcntl.h>
  49 #include <stdio.h>
  50 #include <stdlib.h>
  51 #include <string.h>
  52
  53 #include "mp.h"
  54 #include "pk.h"
  55
  56 static void adjust(char keyout[HEXKEYBYTES+1], char *keyin);
  57
  58 /*
  59  * Choose top 128 bits of the common key to use as our idea key.
  60  */
  61 static void
  62 extractideakey(MINT *ck, IdeaData *ideakey)
  63 {
  64         MINT *a;
  65         MINT *z;
  66         short r;
  67         int i;
  68         short base = (1 << 8);
  69         char *k;
  70
  71         z = itom(0);
  72         a = itom(0);
  73         madd(ck, z, a);
  74         for (i = 0; i < ((KEYSIZE - 128) / 8); i++) {
  75                 sdiv(a, base, a, &r);
  76         }
  77         k = (char *)ideakey;
  78         for (i = 0; i < 16; i++) {
  79                 sdiv(a, base, a, &r);
  80                 *k++ = r;
  81         }
  82         mfree(z);
  83         mfree(a);
  84 }
  85
  86 /*
  87  * Choose middle 64 bits of the common key to use as our des key, possibly
  88  * overwriting the lower order bits by setting parity.
  89  */
  90 static void
  91 extractdeskey(MINT *ck, DesData *deskey)
  92 {
  93         MINT *a;
  94         MINT *z;
  95         short r;
  96         int i;
  97         short base = (1 << 8);
  98         char *k;
  99
 100         z = itom(0);
 101         a = itom(0);
 102         madd(ck, z, a);
 103         for (i = 0; i < ((KEYSIZE - 64) / 2) / 8; i++) {
 104                 sdiv(a, base, a, &r);
 105         }
 106         k = (char *)deskey;
 107         for (i = 0; i < 8; i++) {
 108                 sdiv(a, base, a, &r);
 109                 *k++ = r;
 110         }
 111         mfree(z);
 112         mfree(a);
 113 }
 114
 115 /*
 116  * get common key from my secret key and his public key
 117  */
 118 void
 119 common_key(char *xsecret, char *xpublic, IdeaData *ideakey, DesData *deskey)
 120 {
 121         MINT *public;
 122         MINT *secret;
 123         MINT *common;
 124         MINT *modulus = xtom(HEXMODULUS);
 125
 126         public = xtom(xpublic);
 127         secret = xtom(xsecret);
 128         common = itom(0);
 129         pow(public, secret, modulus, common);
 130         extractdeskey(common, deskey);
 131         extractideakey(common, ideakey);
 132         des_set_odd_parity(deskey);
 133         mfree(common);
 134         mfree(secret);
 135         mfree(public);
 136         mfree(modulus);
 137 }
 138
 139 /*
 140  * Generate a seed
 141  */
 142 static void
 143 getseed(char *seed, int seedsize)
 144 {
 145         int i;
 146
 147         srandomdev();
 148         for (i = 0; i < seedsize; i++) {
 149                 seed[i] = random() & 0xff;
 150         }
 151 }
 152
 153 /*
 154  * Generate a random public/secret key pair
 155  */
 156 void
 157 genkeys(char *public, char *secret)
 158 {
 159         size_t i;
 160
 161 #       define BASEBITS (8*sizeof(short) - 1)
 162 #       define BASE (1 << BASEBITS)
 163
 164         MINT *pk = itom(0);
 165         MINT *sk = itom(0);
 166         MINT *tmp;
 167         MINT *base = itom(BASE);
 168         MINT *root = itom(PROOT);
 169         MINT *modulus = xtom(HEXMODULUS);
 170         short r;
 171         unsigned short seed[KEYSIZE/BASEBITS + 1];
 172         char *xkey;
 173
 174         getseed((char *)seed, sizeof(seed));
 175         for (i = 0; i < KEYSIZE/BASEBITS + 1; i++) {
 176                 r = seed[i] % BASE;
 177                 tmp = itom(r);
 178                 mult(sk, base, sk);
 179                 madd(sk, tmp, sk);
 180                 mfree(tmp);
 181         }
 182         tmp = itom(0);
 183         mdiv(sk, modulus, tmp, sk);
 184         mfree(tmp);
 185         pow(root, sk, modulus, pk);
 186         xkey = mtox(sk);
 187         adjust(secret, xkey);
 188         xkey = mtox(pk);
 189         adjust(public, xkey);
 190         mfree(sk);
 191         mfree(base);
 192         mfree(pk);
 193         mfree(root);
 194         mfree(modulus);
 195 }
 196
 197 /*
 198  * Adjust the input key so that it is 0-filled on the left
 199  */
 200 static void
 201 adjust(char keyout[HEXKEYBYTES+1], char *keyin)
 202 {
 203         char *p;
 204         char *s;
 205
 206         for (p = keyin; *p; p++)
 207                 ;
 208         for (s = keyout + HEXKEYBYTES; p >= keyin; p--, s--) {
 209                 *s = *p;
 210         }
 211         while (s >= keyout) {
 212                 *s-- = '0';
 213         }
 214 }
 215
 216 static char hextab[17] = "0123456789ABCDEF";
 217
 218 /* given a DES key, cbc encrypt and translate input to terminated hex */
 219 void
 220 pk_encode(char *in, char *out, DesData *key)
 221 {
 222         char buf[256];
 223         DesData i;
 224         des_key_schedule k;
 225         int l,op,deslen;
 226
 227         memset(&i,0,sizeof(i));
 228         memset(buf,0,sizeof(buf));
 229         deslen = ((strlen(in) + 7)/8)*8;
 230         des_key_sched(key, k);
 231         des_cbc_encrypt(in,buf,deslen, k,&i,DES_ENCRYPT);
 232         for (l=0,op=0;l<deslen;l++) {
 233                 out[op++] = hextab[(buf[l] & 0xf0) >> 4];
 234                 out[op++] = hextab[(buf[l] & 0x0f)];
 235         }
 236         out[op] = '\0';
 237 }
 238
 239 /* given a DES key, translate input from hex and decrypt */
 240 void
 241 pk_decode(char *in, char *out, DesData *key)
 242 {
 243         char buf[256];
 244         DesData i;
 245         des_key_schedule k;
 246         int n1,n2,op;
 247         size_t l;
 248
 249         memset(&i,0,sizeof(i));
 250         memset(buf,0,sizeof(buf));
 251         for (l=0,op=0;l<strlen(in)/2;l++,op+=2) {
 252                 if (in[op] > '9')
 253                         n1 = in[op] - 'A' + 10;
 254                 else
 255                         n1 = in[op] - '0';
 256                 if (in[op+1] > '9')
 257                         n2 = in[op+1] - 'A' + 10;
 258                 else
 259                         n2 = in[op+1] - '0';
 260                 buf[l] = n1*16 +n2;
 261         }
 262         des_key_sched(key, k);
 263         des_cbc_encrypt(buf,out,strlen(in)/2, k,&i,DES_DECRYPT);
 264         out[strlen(in)/2] = '\0';
 265 }