243 lines
5.2 KiB
C
243 lines
5.2 KiB
C
/* public key routines */
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/* functions:
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genkeys(char *public, char *secret)
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common_key(char *secret, char *public, desData *deskey)
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pk_encode(char *in, *out, DesData *deskey);
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pk_decode(char *in, *out, DesData *deskey);
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where
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char public[HEXKEYBYTES + 1];
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char secret[HEXKEYBYTES + 1];
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/time.h>
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#include <openssl/des.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include "mp.h"
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#include "pk.h"
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#if defined(SOLARIS2) || defined(LINUX) || defined(__FreeBSD__)
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#include <stdlib.h>
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#endif
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static void adjust(char keyout[HEXKEYBYTES+1], char *keyin);
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/*
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* Choose top 128 bits of the common key to use as our idea key.
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*/
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static void
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extractideakey(MINT *ck, IdeaData *ideakey)
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{
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MINT *a;
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MINT *z;
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short r;
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int i;
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short base = (1 << 8);
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char *k;
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z = itom(0);
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a = itom(0);
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madd(ck, z, a);
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for (i = 0; i < ((KEYSIZE - 128) / 8); i++) {
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sdiv(a, base, a, &r);
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}
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k = (char *)ideakey;
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for (i = 0; i < 16; i++) {
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sdiv(a, base, a, &r);
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*k++ = r;
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}
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mfree(z);
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mfree(a);
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}
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/*
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* Choose middle 64 bits of the common key to use as our des key, possibly
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* overwriting the lower order bits by setting parity.
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*/
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static void
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extractdeskey(MINT *ck, DesData *deskey)
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{
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MINT *a;
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MINT *z;
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short r;
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int i;
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short base = (1 << 8);
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char *k;
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z = itom(0);
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a = itom(0);
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madd(ck, z, a);
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for (i = 0; i < ((KEYSIZE - 64) / 2) / 8; i++) {
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sdiv(a, base, a, &r);
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}
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k = (char *)deskey;
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for (i = 0; i < 8; i++) {
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sdiv(a, base, a, &r);
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*k++ = r;
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}
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mfree(z);
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mfree(a);
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}
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/*
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* get common key from my secret key and his public key
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*/
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void
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common_key(char *xsecret, char *xpublic, IdeaData *ideakey, DesData *deskey)
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{
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MINT *public;
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MINT *secret;
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MINT *common;
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MINT *modulus = xtom(HEXMODULUS);
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public = xtom(xpublic);
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secret = xtom(xsecret);
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common = itom(0);
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pow(public, secret, modulus, common);
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extractdeskey(common, deskey);
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extractideakey(common, ideakey);
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#if DES_OSTHOLM
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des_fixup_key_parity(deskey);
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#else
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des_set_odd_parity(deskey);
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#endif
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mfree(common);
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mfree(secret);
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mfree(public);
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mfree(modulus);
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}
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/*
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* Generate a seed
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*/
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void
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getseed(char *seed, int seedsize)
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{
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int i;
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srandomdev();
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for (i = 0; i < seedsize; i++) {
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seed[i] = random() & 0xff;
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}
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}
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/*
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* Generate a random public/secret key pair
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*/
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void
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genkeys(char *public, char *secret)
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{
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int i;
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# define BASEBITS (8*sizeof(short) - 1)
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# define BASE (1 << BASEBITS)
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MINT *pk = itom(0);
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MINT *sk = itom(0);
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MINT *tmp;
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MINT *base = itom(BASE);
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MINT *root = itom(PROOT);
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MINT *modulus = xtom(HEXMODULUS);
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short r;
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unsigned short seed[KEYSIZE/BASEBITS + 1];
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char *xkey;
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getseed((char *)seed, sizeof(seed));
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for (i = 0; i < KEYSIZE/BASEBITS + 1; i++) {
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r = seed[i] % BASE;
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tmp = itom(r);
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mult(sk, base, sk);
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madd(sk, tmp, sk);
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mfree(tmp);
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}
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tmp = itom(0);
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mdiv(sk, modulus, tmp, sk);
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mfree(tmp);
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pow(root, sk, modulus, pk);
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xkey = mtox(sk);
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adjust(secret, xkey);
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xkey = mtox(pk);
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adjust(public, xkey);
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mfree(sk);
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mfree(base);
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mfree(pk);
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mfree(root);
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mfree(modulus);
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}
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/*
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* Adjust the input key so that it is 0-filled on the left
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*/
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static void
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adjust(char keyout[HEXKEYBYTES+1], char *keyin)
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{
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char *p;
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char *s;
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for (p = keyin; *p; p++)
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;
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for (s = keyout + HEXKEYBYTES; p >= keyin; p--, s--) {
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*s = *p;
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}
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while (s >= keyout) {
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*s-- = '0';
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}
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}
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static char hextab[17] = "0123456789ABCDEF";
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/* given a DES key, cbc encrypt and translate input to terminated hex */
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void
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pk_encode(char *in, char *out, DesData *key)
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{
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char buf[256];
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DesData i;
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des_key_schedule k;
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int l,op,deslen;
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memset(&i,0,sizeof(i));
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memset(buf,0,sizeof(buf));
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deslen = ((strlen(in) + 7)/8)*8;
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des_key_sched(key, k);
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des_cbc_encrypt(in,buf,deslen, k,&i,DES_ENCRYPT);
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for (l=0,op=0;l<deslen;l++) {
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out[op++] = hextab[(buf[l] & 0xf0) >> 4];
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out[op++] = hextab[(buf[l] & 0x0f)];
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}
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out[op] = '\0';
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}
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/* given a DES key, translate input from hex and decrypt */
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void
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pk_decode(char *in, char *out, DesData *key)
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{
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char buf[256];
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DesData i;
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des_key_schedule k;
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int l,n1,n2,op;
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memset(&i,0,sizeof(i));
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memset(buf,0,sizeof(buf));
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for (l=0,op=0;l<strlen(in)/2;l++,op+=2) {
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if(in[op] == '0' && in[op+1] == '0') {
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buf[l] = '\0';
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break;
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}
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if (in[op] > '9')
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n1 = in[op] - 'A' + 10;
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else
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n1 = in[op] - '0';
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if (in[op+1] > '9')
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n2 = in[op+1] - 'A' + 10;
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else
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n2 = in[op+1] - '0';
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buf[l] = n1*16 +n2;
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}
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des_key_sched(key, k);
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des_cbc_encrypt(buf,out,strlen(in)/2, k,&i,DES_DECRYPT);
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out[strlen(in)/2] = '\0';
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}
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