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/* public key routines */
/* $FreeBSD$ */
/* 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 <string.h>
#include "mp.h"
#include "pk.h"
#if defined(SOLARIS2) || defined(LINUX) || defined(__FreeBSD__)
#include <stdlib.h>
#endif
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 = itom(0);
a = itom(0);
madd(ck, z, a);
for (i = 0; i < ((KEYSIZE - 128) / 8); i++) {
sdiv(a, base, a, &r);
}
k = (char *)ideakey;
for (i = 0; i < 16; i++) {
sdiv(a, base, a, &r);
*k++ = r;
}
mfree(z);
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 = itom(0);
a = itom(0);
madd(ck, z, a);
for (i = 0; i < ((KEYSIZE - 64) / 2) / 8; i++) {
sdiv(a, base, a, &r);
}
k = (char *)deskey;
for (i = 0; i < 8; i++) {
sdiv(a, base, a, &r);
*k++ = r;
}
mfree(z);
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 = xtom(HEXMODULUS);
public = xtom(xpublic);
secret = xtom(xsecret);
common = itom(0);
pow(public, secret, modulus, common);
extractdeskey(common, deskey);
extractideakey(common, ideakey);
#if DES_OSTHOLM
des_fixup_key_parity(deskey);
#else
des_set_odd_parity(deskey);
#endif
mfree(common);
mfree(secret);
mfree(public);
mfree(modulus);
}
/*
* Generate a seed
*/
void
getseed(char *seed, int seedsize)
{
int i;
srandomdev();
for (i = 0; i < seedsize; i++) {
seed[i] = random() & 0xff;
}
}
/*
* Generate a random public/secret key pair
*/
void
genkeys(char *public, char *secret)
{
int i;
# define BASEBITS (8*sizeof(short) - 1)
# define BASE (1 << BASEBITS)
MINT *pk = itom(0);
MINT *sk = itom(0);
MINT *tmp;
MINT *base = itom(BASE);
MINT *root = itom(PROOT);
MINT *modulus = 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 = itom(r);
mult(sk, base, sk);
madd(sk, tmp, sk);
mfree(tmp);
}
tmp = itom(0);
mdiv(sk, modulus, tmp, sk);
mfree(tmp);
pow(root, sk, modulus, pk);
xkey = mtox(sk);
adjust(secret, xkey);
xkey = mtox(pk);
adjust(public, xkey);
mfree(sk);
mfree(base);
mfree(pk);
mfree(root);
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 l,n1,n2,op;
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] == '0' && in[op+1] == '0') {
buf[l] = '\0';
break;
}
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';
}
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