freebsd-dev/contrib/telnet/libtelnet/pk.c
Conrad Meyer 23c30549af libtelnet: Replace bogus use of srandomdev + random to generate "public key pair"
I'm pretty skeptical that any crypto in telnet is worth using, but if we're
ostensibly generating keys, arc4random is strictly better than the previous
construct.
2019-12-13 05:42:57 +00:00

261 lines
6.7 KiB
C

/*-
* Copyright (c) 1991, 1993
* Dave Safford. 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. 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/* public key routines */
/* functions:
genkeys(char *public, char *secret)
common_key(char *secret, char *public, desData *deskey)
pk_encode(char *in, *out, DesData *deskey);
pk_decode(char *in, *out, DesData *deskey);
where
char public[HEXKEYBYTES + 1];
char secret[HEXKEYBYTES + 1];
*/
#include <sys/time.h>
#include <openssl/des.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "mp.h"
#include "pk.h"
static void adjust(char keyout[HEXKEYBYTES+1], char *keyin);
/*
* Choose top 128 bits of the common key to use as our idea key.
*/
static void
extractideakey(MINT *ck, IdeaData *ideakey)
{
MINT *a;
MINT *z;
short r;
int i;
short base = (1 << 8);
char *k;
z = mp_itom(0);
a = mp_itom(0);
mp_madd(ck, z, a);
for (i = 0; i < ((KEYSIZE - 128) / 8); i++) {
mp_sdiv(a, base, a, &r);
}
k = (char *)ideakey;
for (i = 0; i < 16; i++) {
mp_sdiv(a, base, a, &r);
*k++ = r;
}
mp_mfree(z);
mp_mfree(a);
}
/*
* Choose middle 64 bits of the common key to use as our des key, possibly
* overwriting the lower order bits by setting parity.
*/
static void
extractdeskey(MINT *ck, DesData *deskey)
{
MINT *a;
MINT *z;
short r;
int i;
short base = (1 << 8);
char *k;
z = mp_itom(0);
a = mp_itom(0);
mp_madd(ck, z, a);
for (i = 0; i < ((KEYSIZE - 64) / 2) / 8; i++) {
mp_sdiv(a, base, a, &r);
}
k = (char *)deskey;
for (i = 0; i < 8; i++) {
mp_sdiv(a, base, a, &r);
*k++ = r;
}
mp_mfree(z);
mp_mfree(a);
}
/*
* get common key from my secret key and his public key
*/
void
common_key(char *xsecret, char *xpublic, IdeaData *ideakey, DesData *deskey)
{
MINT *public;
MINT *secret;
MINT *common;
MINT *modulus = mp_xtom(HEXMODULUS);
public = mp_xtom(xpublic);
secret = mp_xtom(xsecret);
common = mp_itom(0);
mp_pow(public, secret, modulus, common);
extractdeskey(common, deskey);
extractideakey(common, ideakey);
DES_set_odd_parity(deskey);
mp_mfree(common);
mp_mfree(secret);
mp_mfree(public);
mp_mfree(modulus);
}
/*
* Generate a seed
*/
static void
getseed(char *seed, int seedsize)
{
arc4random_buf(seed, seedsize);
}
/*
* Generate a random public/secret key pair
*/
void
genkeys(char *public, char *secret)
{
size_t i;
# define BASEBITS (8*sizeof(short) - 1)
# define BASE (1 << BASEBITS)
MINT *pk = mp_itom(0);
MINT *sk = mp_itom(0);
MINT *tmp;
MINT *base = mp_itom((short)BASE);
MINT *root = mp_itom(PROOT);
MINT *modulus = mp_xtom(HEXMODULUS);
short r;
unsigned short seed[KEYSIZE/BASEBITS + 1];
char *xkey;
getseed((char *)seed, sizeof(seed));
for (i = 0; i < KEYSIZE/BASEBITS + 1; i++) {
r = seed[i] % BASE;
tmp = mp_itom(r);
mp_mult(sk, base, sk);
mp_madd(sk, tmp, sk);
mp_mfree(tmp);
}
tmp = mp_itom(0);
mp_mdiv(sk, modulus, tmp, sk);
mp_mfree(tmp);
mp_pow(root, sk, modulus, pk);
xkey = mp_mtox(sk);
adjust(secret, xkey);
xkey = mp_mtox(pk);
adjust(public, xkey);
mp_mfree(sk);
mp_mfree(base);
mp_mfree(pk);
mp_mfree(root);
mp_mfree(modulus);
}
/*
* Adjust the input key so that it is 0-filled on the left
*/
static void
adjust(char keyout[HEXKEYBYTES+1], char *keyin)
{
char *p;
char *s;
for (p = keyin; *p; p++)
;
for (s = keyout + HEXKEYBYTES; p >= keyin; p--, s--) {
*s = *p;
}
while (s >= keyout) {
*s-- = '0';
}
}
static char hextab[17] = "0123456789ABCDEF";
/* given a DES key, cbc encrypt and translate input to terminated hex */
void
pk_encode(char *in, char *out, DesData *key)
{
char buf[256];
DesData i;
DES_key_schedule k;
int l,op,deslen;
memset(&i,0,sizeof(i));
memset(buf,0,sizeof(buf));
deslen = ((strlen(in) + 7)/8)*8;
DES_key_sched(key, &k);
DES_cbc_encrypt(in, buf, deslen, &k, &i, DES_ENCRYPT);
for (l=0,op=0;l<deslen;l++) {
out[op++] = hextab[(buf[l] & 0xf0) >> 4];
out[op++] = hextab[(buf[l] & 0x0f)];
}
out[op] = '\0';
}
/* given a DES key, translate input from hex and decrypt */
void
pk_decode(char *in, char *out, DesData *key)
{
char buf[256];
DesData i;
DES_key_schedule k;
int n1,n2,op;
size_t l;
memset(&i,0,sizeof(i));
memset(buf,0,sizeof(buf));
for (l=0,op=0;l<strlen(in)/2;l++,op+=2) {
if (in[op] > '9')
n1 = in[op] - 'A' + 10;
else
n1 = in[op] - '0';
if (in[op+1] > '9')
n2 = in[op+1] - 'A' + 10;
else
n2 = in[op+1] - '0';
buf[l] = n1*16 +n2;
}
DES_key_sched(key, &k);
DES_cbc_encrypt(buf, out, strlen(in) / 2, &k, &i, DES_DECRYPT);
out[strlen(in)/2] = '\0';
}