NetBSD-5.0.2/lib/libtelnet/pk.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>
#ifdef notdef
__FBSDID("$FreeBSD: src/contrib/telnet/libtelnet/pk.c,v 1.10 2002/08/22 06:19:07 nsayer Exp $");
#else
__RCSID("$NetBSD: pk.c,v 1.4 2005/02/19 22:55:35 christos Exp $");
#endif
/* 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 <des.h>
#include <openssl/bn.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pk.h"
static void adjust(char *, const char *);
/*
* Choose top 128 bits of the common key to use as our idea key.
*/
static void
extractideakey(BIGNUM *ck, IdeaData *ideakey)
{
BIGNUM *a = BN_new();
BIGNUM *z = BN_new();
BIGNUM *base = BN_new();
BN_CTX *ctx = BN_CTX_new();
size_t i;
char *k;
(void)BN_zero(a);
(void)BN_zero(z);
(void)BN_set_word(base, 1 << 8);
BN_add(a, ck, z);
for (i = 0; i < ((KEYSIZE - 128) / 8); i++)
BN_div(a, z, a, base, ctx);
k = (char *)(void *)ideakey;
for (i = 0; i < 16; i++) {
BN_div(a, z, a, base, ctx);
*k++ = (char)BN_get_word(z);
}
BN_CTX_free(ctx);
BN_free(base);
BN_free(z);
BN_free(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(BIGNUM *ck, DesData *deskey)
{
BIGNUM *a = BN_new();
BIGNUM *z = BN_new();
BIGNUM *base = BN_new();
BN_CTX *ctx = BN_CTX_new();
size_t i;
char *k;
(void)BN_zero(z);
(void)BN_zero(a);
(void)BN_set_word(base, 1 << 8);
BN_add(a, ck, z);
for (i = 0; i < ((KEYSIZE - 64) / 2) / 8; i++)
BN_div(a, z, a, base, ctx);
k = (char *)deskey;
for (i = 0; i < 8; i++) {
BN_div(a, z, a, base, ctx);
*k++ = (char)BN_get_word(z);
}
BN_CTX_free(ctx);
BN_free(base);
BN_free(z);
BN_free(a);
}
/*
* get common key from my secret key and his public key
*/
void
common_key(char *xsecret, char *xpublic, IdeaData *ideakey, DesData *deskey)
{
BIGNUM *public = BN_new();
BIGNUM *secret = BN_new();
BIGNUM *common = BN_new();
BIGNUM *modulus = BN_new();
BN_CTX *ctx = BN_CTX_new();
(void)BN_hex2bn(&modulus, HEXMODULUS);
(void)BN_hex2bn(&public, xpublic);
(void)BN_hex2bn(&secret, xsecret);
(void)BN_zero(common);
BN_mod_exp(common, public, secret, modulus, ctx);
extractdeskey(common, deskey);
extractideakey(common, ideakey);
des_set_odd_parity(deskey);
BN_CTX_free(ctx);
BN_free(common);
BN_free(secret);
BN_free(public);
BN_free(modulus);
}
/*
* Generate a seed
*/
static void
getseed(char *seed, size_t seedsize)
{
size_t i;
for (i = 0; i < seedsize; i++)
seed[i] = arc4random() & 0xff;
}
/*
* 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)
BIGNUM *pk = BN_new();
BIGNUM *sk = BN_new();
BIGNUM *tmp = BN_new();
BIGNUM *base = BN_new();
BIGNUM *root = BN_new();
BIGNUM *modulus = BN_new();
BN_CTX *ctx = BN_CTX_new();
short r;
unsigned short seed[KEYSIZE/BASEBITS + 1];
char *xkey;
(void)BN_zero(pk);
(void)BN_zero(sk);
(void)BN_set_word(base, BASE);
(void)BN_set_word(root, PROOT);
(void)BN_hex2bn(&modulus, HEXMODULUS);
getseed((char *)seed, sizeof(seed));
for (i = 0; i < KEYSIZE/BASEBITS + 1; i++) {
r = seed[i] % BASE;
(void)BN_set_word(tmp, r);
BN_mul(sk, tmp, sk, ctx);
BN_add(sk, tmp, sk);
}
(void)BN_zero(tmp);
BN_div(tmp, sk, sk, modulus, ctx);
BN_mod_exp(pk, root, sk, modulus, ctx);
xkey = BN_bn2hex(sk);
adjust(secret, xkey);
xkey = BN_bn2hex(pk);
adjust(public, xkey);
BN_CTX_free(ctx);
BN_free(sk);
BN_free(base);
BN_free(pk);
BN_free(tmp);
BN_free(root);
BN_free(modulus);
}
/*
* Adjust the input key so that it is 0-filled on the left
*/
static void
adjust(char *keyout, const char *keyin)
{
const char *p;
char *s;
for (p = keyin; *p; p++)
continue;
for (s = keyout + HEXKEYBYTES; p >= keyin; p--, s--)
*s = *p;
while (s >= keyout)
*s-- = '0';
}
static const char hextab[] = "0123456789ABCDEF";
/* given a DES key, cbc encrypt and translate input to terminated hex */
void
pk_encode(const char *in, char *out, DesData *key)
{
char buf[256];
DesData i;
des_key_schedule k;
size_t l, op, deslen;
(void)memset(&i, 0, sizeof(i));
(void)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(const char *in, char *out, DesData *key)
{
char buf[256];
DesData i;
des_key_schedule k;
int n1, n2, op;
size_t l;
size_t len = strlen(in) / 2;
(void)memset(&i, 0, sizeof(i));
(void)memset(buf, 0, sizeof(buf));
for (l = 0, op = 0; l < len; 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] = (char)(n1 * 16 + n2);
}
des_key_sched(key, k);
des_cbc_encrypt(buf, out, len, k, &i, DES_DECRYPT);
out[len] = '\0';
}