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/*
* keygen.c
* WEP Key Generators
*
* This program generates WEP keys using de facto standard key
* generators for 40 and 128 bit keys.
*
* Link against OpenSSL's libcrypto.a
*
* I place this code in the public domain.
* May 2001, Tim Newsham
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <openssl/md5.h>
#define WEPKEYSIZE 5
#define WEPSTRONGKEYSIZE 13
#define WEPKEYS 4
#define WEPKEYSTORE (WEPKEYSIZE * WEPKEYS)
/*
* generate four subkeys from a seed using the defacto standard
*/
void
wep_seedkeygen(int val, u_char *keys)
{
int i;
for(i = 0; i < WEPKEYSTORE; i++) {
val *= 0x343fd;
val += 0x269ec3;
keys[i] = val >> 16;
}
return;
}
/*
* generate one key from a string using the de facto standard
*
* resultant key is stored in
* one 128 bit key: keys[0-15]
*
* (NOTE: I'm not sure why, but it seems that only values 0-12 are used,
* resulting in 104 bits of keying, not 128)
*/
void
wep_keygen128(char *str, u_char *keys)
{
MD5_CTX ctx;
u_char buf[64];
int i, j;
/* repeat str until buf is full */
j = 0;
for(i = 0; i < 64; i++) {
if(str[j] == 0)
j = 0;
buf[i] = str[j++];
}
MD5_Init(&ctx);
MD5_Update(&ctx, buf, sizeof buf);
MD5_Final(buf, &ctx);
memcpy(keys, buf, WEPKEYSTORE);
for(i = 0; i < WEPSTRONGKEYSIZE; i++) {
keys[i] = buf[i];
}
for(; i < WEPKEYSTORE; i++) {
keys[i] = 0;
}
return;
}
/*
* generate four subkeys from a string using the defacto standard
*
* resultant keys are stored in
* four 40 bit keys: keys[0-4], keys[5-9], keys[10-14] and keys[15-20]
*/
void
wep_keygen40(char *str, u_char *keys)
{
int val, i, shift;
/*
* seed is generated by xor'ing in the keystring bytes
* into the four bytes of the seed, starting at the little end
*/
val = 0;
for(i = 0; str[i]; i++) {
shift = i & 0x3;
val ^= (str[i] << (shift * 8));
}
wep_seedkeygen(val, keys);
return;
}
void
wep_keyprint(u_char *keys, int strong)
{
int i, printlength, keylength;
char sepchar;
printlength = strong ? WEPSTRONGKEYSIZE : WEPKEYSTORE;
keylength = strong ? WEPSTRONGKEYSIZE : WEPKEYSIZE;
for(i = 0; i < printlength; i++) {
sepchar = (i % keylength == keylength - 1) ? '\n' : ':';
printf("%02x%c", keys[i], sepchar);
}
return;
}
void
usage(char *prog)
{
printf("%s: generates Lucent compatible WEP keys from a string\n", prog);
printf("Usage: %s [-s] keystring\n", prog);
exit(1);
}
int
main(int argc, char **argv)
{
u_char keys[WEPKEYSTORE];
char *prog, *genstr;
int strong, ch;
prog = argv[0];
strong = 0;
while((ch = getopt(argc, argv, "s")) != EOF) {
switch(ch) {
case 's':
strong ++;
break;
default:
usage(prog);
}
}
argc -= optind;
argv += optind;
if(argc != 1)
usage(prog);
genstr = argv[0];
if(strong)
wep_keygen128(genstr, keys);
else
wep_keygen40(genstr, keys);
wep_keyprint(keys, strong);
return 0;
}
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