2674533 [rkeene@sledge /home/rkeene/devel/dact]$ cat -n cipher_psub.c
  1 /*
  2  * Copyright (C) 2001, 2002, and 2003  Roy Keene
  3  *
  4  * This program is free software; you can redistribute it and/or
  5  * modify it under the terms of the GNU General Public License
  6  * as published by the Free Software Foundation; either version 2
  7  * of the License, or (at your option) any later version.
  8  *
  9  * This program is distributed in the hope that it will be useful,
 10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12  * GNU General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, write to the Free Software
 16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 17  *
 18  *      email: dact@rkeene.org
 19  */
 20 
 21 /*
 22     Encrypt data.
 23 */
 24 #include "dact.h"
 25 #ifdef HAVE_UNISTD_H
 26 #include <unistd.h>
 27 #endif
 28 #ifdef HAVE_STDLIB_H
 29 #include <stdlib.h>
 30 #endif
 31 #ifdef HAVE_STRING_H
 32 #include <string.h>
 33 #endif
 34 #ifdef HAVE_SYS_TYPES_H
 35 #include <sys/types.h>
 36 #endif
 37 #ifdef HAVE_SYS_STAT_H
 38 #include <sys/stat.h>
 39 #endif
 40 #include <fcntl.h>
 41 #include <stdio.h>
 42 #include <math.h>
 43 #include "cipher_psub.h"
 44 #include "parse.h"
 45 #include "ui.h"
 46 
 47 #if defined(USE_MODULES) && defined(AS_MODULE)
 48 #include "module.h"
 49 uint32_t DC_NUM=3;
 50 uint32_t DC_TYPE=DACT_MOD_TYPE_ENC;
 51 void *DC_ALGO=cipher_psub;
 52 char *DC_NAME="psubst (MOD)";
 53 #endif
 54 
 55 
 56 int cipher_psub(const unsigned char *inblock, unsigned char *outblock, const int blksize, unsigned char *key, const int
	mode) {
 57     switch (mode) {
 58         case (DACT_MODE_CINIT+DACT_MODE_CDEC):
 59         case (DACT_MODE_CINIT+DACT_MODE_CENC):
 60         case DACT_MODE_CINIT:
 61             return(cipher_psub_init(mode,key));
 62             break;
 63         case DACT_MODE_CDEC:
 64             return(cipher_psub_decrypt(inblock, outblock, blksize, key));
 65             break;
 66         case DACT_MODE_CENC:
 67             return(cipher_psub_encrypt(inblock, outblock, blksize, key));
 68             break;
 69     }
 70     return(0);
 71 }
 72 
 73 
 74 int cipher_psub_init(const int mode, unsigned char *key) {
 75     return(cipher_psub_init_getkey(mode-DACT_MODE_CINIT,key));
 76 }
 77 
 78 int cipher_psub_init_getkey(const int mode, unsigned char *key) {
 79     unsigned char *phrase;
 80     char *keyreg;
 81 
 82     phrase=dact_ui_getuserinput("Passphrase: ",128,1);
 83 
 84     memcpy(key,keyreg=cipher_psub_generatekey(phrase),257);
 85     free(keyreg);
 86     return(257);
 87 }
 88 
 89 char *cipher_psub_generatekey(const char *passphrase) {
 90     char *keybuf, used[256], hbuf[4];
 91     int i,m,x,loc=0,num;
 92     double d;
 93 
 94     keybuf=malloc(1024);
 95 
 96     for (i=0;i<256;i++) used[i]=0;
 97 
 98     if (strlen(passphrase)<3) { num=257; } else { num=((259/((int) (strlen(passphrase)/3)))+1); }
 99 
100     for (m=0;m<strlen(passphrase);m+=3) {
101         memcpy(hbuf,passphrase+m,3);
102         hbuf[3]='\0';
103         d=hash_fourbyte(hbuf, '\0');
104         for (i=0;i<num;i++) {
105             d=(sin(tan(d))*(255*5));
106             x=((abs((int) d)&0x3ff)-255);
107             if (x<0 || x>255 || used[x]) { i--; continue; }
108             used[x]=1;
109             if (loc==0) used[x]=0;
110             keybuf[loc++]=x;
111             if (loc==257) break;
112         }
113         if (loc==257) break;
114     }
115     return(keybuf);
116 }
117 
118 int cipher_psub_encrypt(const unsigned char *inblk, unsigned char *outblk, int blksize, unsigned char *key) {
119     int i,mod;
120     static int keyoffset=0;
121 
122     mod=(int) key[0];
123     for (i=0;i<blksize;i++) {
124         if (!(i%mod)) {
125             keyoffset=((keyoffset+1)&0xff);
126         }
127         outblk[i]=key[((((int) inblk[i])+keyoffset)&0xff)+1];
128     }
129     return(blksize);
130 }
131 
132 int cipher_psub_decrypt(const unsigned char *inblk, unsigned char *outblk, int blksize, unsigned char *key) {
133     int i,mod,x;
134     char reversekey[256];
135     static int keyoffset=0;
136 
137     mod=(int) key[0];
138     for (i=1;i<257;i++) reversekey[(int) key[i]]=(i-1);
139     for (i=0;i<blksize;i++) {
140         if (!(i%mod)) {
141             keyoffset=((keyoffset+1)&0xff);
142             for (x=0;x<256;x++) reversekey[(int) key[((x+keyoffset)&0xff)+1]]=x;
143         }
144         outblk[i]=reversekey[(int) inblk[i]];
145     }
146     return(blksize);
147 }
2674534 [rkeene@sledge /home/rkeene/devel/dact]$

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last modified: 2004-04-04 01:01:49