Logo Search packages:      
Sourcecode: dact version File versions  Download package

cipher_psub.c

/*
 * Copyright (C) 2001, 2002, and 2003  Roy Keene
 *
 * 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.
 *
 *      email: dact@rkeene.org
 */

/*
      Encrypt data.
*/
#include "dact.h"
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#include <fcntl.h>
#include <stdio.h>
#include <math.h>
#include "cipher_psub.h"
#include "parse.h"
#include "ui.h"

#if defined(USE_MODULES) && defined(AS_MODULE)
#include "module.h"
uint32_t DC_NUM=3;
uint32_t DC_TYPE=DACT_MOD_TYPE_ENC;
void *DC_ALGO=cipher_psub;
char *DC_NAME="psubst (MOD)";
#endif


int cipher_psub(const unsigned char *inblock, unsigned char *outblock, const int blksize, unsigned char *key, const int mode) {
      switch (mode) {
            case (DACT_MODE_CINIT+DACT_MODE_CDEC):
            case (DACT_MODE_CINIT+DACT_MODE_CENC):
            case DACT_MODE_CINIT:
                  return(cipher_psub_init(mode,key));
                  break;
            case DACT_MODE_CDEC:
                  return(cipher_psub_decrypt(inblock, outblock, blksize, key));
                  break;
            case DACT_MODE_CENC:
                  return(cipher_psub_encrypt(inblock, outblock, blksize, key));
                  break;
      }
      return(0);
}


int cipher_psub_init(const int mode, unsigned char *key) {
      return(cipher_psub_init_getkey(mode-DACT_MODE_CINIT,key));
}

int cipher_psub_init_getkey(const int mode, unsigned char *key) {
      unsigned char *phrase;
      char *keyreg;

      phrase=dact_ui_getuserinput("Passphrase: ",128,1);

      memcpy(key,keyreg=cipher_psub_generatekey(phrase),257);
      free(keyreg);
      return(257);
}

char *cipher_psub_generatekey(const char *passphrase) {
      char *keybuf, used[256], hbuf[4];
      int i,m,x,loc=0,num;
      double d;

      keybuf=malloc(1024);

      for (i=0;i<256;i++) used[i]=0;

      if (strlen(passphrase)<3) { num=257; } else { num=((259/((int) (strlen(passphrase)/3)))+1); }

      for (m=0;m<strlen(passphrase);m+=3) {
            memcpy(hbuf,passphrase+m,3);
            hbuf[3]='\0';
            d=hash_fourbyte(hbuf, '\0');
            for (i=0;i<num;i++) {
                  d=(sin(tan(d))*(255*5));
                  x=((abs((int) d)&0x3ff)-255);
                  if (x<0 || x>255 || used[x]) { i--; continue; }
                  used[x]=1;
                  if (loc==0) used[x]=0;
                  keybuf[loc++]=x;
                  if (loc==257) break;
            }
            if (loc==257) break;
      }
      return(keybuf);
}

int cipher_psub_encrypt(const unsigned char *inblk, unsigned char *outblk, int blksize, unsigned char *key) {
      int i,mod;
      static int keyoffset=0;

      mod=(int) key[0];
      for (i=0;i<blksize;i++) {
            if (!(i%mod)) {
                  keyoffset=((keyoffset+1)&0xff);
            }
            outblk[i]=key[((((int) inblk[i])+keyoffset)&0xff)+1];
      }
      return(blksize);
}

int cipher_psub_decrypt(const unsigned char *inblk, unsigned char *outblk, int blksize, unsigned char *key) {
      int i,mod,x;
      char reversekey[256];
      static int keyoffset=0;

      mod=(int) key[0];
      for (i=1;i<257;i++) reversekey[(int) key[i]]=(i-1);
      for (i=0;i<blksize;i++) {
            if (!(i%mod)) {
                  keyoffset=((keyoffset+1)&0xff);
                  for (x=0;x<256;x++) reversekey[(int) key[((x+keyoffset)&0xff)+1]]=x;
            }
            outblk[i]=reversekey[(int) inblk[i]];
      }
      return(blksize);
}

Generated by  Doxygen 1.6.0   Back to index