/* Password encoder for Cisco VPN client.
Copyright (C) 2009 Sebastian Wicki
Derivated from cisco-decrypt - Copyright (C) 2005 Maurice Massar
Thanks to HAL-9000@evilscientists.de for decoding and posting the algorithm!
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
Requires libgcrypt version 1.1.90 or newer
Compile with:
gcc -Wall -o cisco-encrypt cisco-encrypt.c $(libgcrypt-config --libs --cflags)
Usage:
./cisco-encrypt PASSWORD1 PASSWORD2 ...
*/
#include <stdio.h>
#include <stdlib.h>
#include <gcrypt.h>
#include <errno.h>
#include <time.h>
void printhex(unsigned char *buffer, int length) {
int i;
for(i=0; i<length; i++) {
printf("%02X", buffer[i]);
}
printf("\n");
}
int c_encrypt(const char *pw, int pwlen, char **resp, int *reslenp) {
char ht[20], h1[20], h2[20], h3[20], h4[20], key[24];
const char *iv = h1;
char *res, *enc, *tmp;
int i, enclen = (pwlen%8) ? ((pwlen/8)+1)*8 : pwlen;
gcry_cipher_hd_t ctx;
time_t rawtime;
time(&rawtime);
tmp = ctime(&rawtime);
/* h1 = SHA1 of ctime - bad source for entropy */
gcry_md_hash_buffer(GCRY_MD_SHA1, h1, tmp, strlen(tmp));
/* ht = temporary hash */
memcpy(ht, h1, 20);
/* h2 = SHA1 of modified h1*/
ht[19]++;
gcry_md_hash_buffer(GCRY_MD_SHA1, h2, ht, 20);
/* h3 = SHA1 of modified h2 */
ht[19] += 2;
gcry_md_hash_buffer(GCRY_MD_SHA1, h3, ht, 20);
/* key = h2 + (4 bytes of h3) */
memcpy(key, h2, 20);
memcpy(key+20, h3, 4);
/* allocate buffer for in-place encryption */
enc = malloc(enclen);
if(enc == NULL) {
return -1;
}
memcpy(enc, pw, pwlen);
/* padding */
for(i=pwlen; i<enclen; i++) {
enc[i] = enclen - pwlen;
}
/* encrypt password with 3DES with iv = 8 bytes of h1, key = see above */
gcry_cipher_open(&ctx, GCRY_CIPHER_3DES, GCRY_CIPHER_MODE_CBC, 0);
gcry_cipher_setkey(ctx, key, 24);
gcry_cipher_setiv(ctx, iv, 8);
gcry_cipher_encrypt(ctx, (unsigned char *)enc, enclen, NULL, 0);
gcry_cipher_close(ctx);
/* h4 = SHA1 of encrypted password */
gcry_md_hash_buffer(GCRY_MD_SHA1, h4, enc, enclen);
/* hash length */
*reslenp = enclen+40;
res = malloc(*reslenp);
/* hash = h1 | h4 | encrypted password */
memcpy(res, h1, 20);
memcpy(res+20, h4, 20);
memcpy(res+40, enc, enclen);
*resp = res;
free(enc);
return 0;
}
int main(int argc, char *argv[]) {
int i, ret = 0, pwlen, hashlen;
char *hash;
gcry_check_version(NULL);
for (i = 1; i < argc; i++) {
pwlen = strlen(argv[i])+1;
ret = c_encrypt(argv[i], pwlen, &hash, &hashlen);
if(ret != 0) {
perror("encodig failed");
continue;
}
printhex((unsigned char *)hash, hashlen);
free(hash);
}
exit(ret != 0);
}
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