src/common/passcrypt.c

   1 /*
   2  * Claws Mail -- a GTK based, lightweight, and fast e-mail client
   3  * Copyright (C) 1999-2012 Hiroyuki Yamamoto and the Claws Mail Team
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  17  *
  18  */
  19
  20 #include "config.h"
  21
  22 #include <sys/types.h>
  23 #include <stdio.h>
  24 #include <memory.h>
  25 #include <ctype.h>
  26 #include <stdlib.h>
  27 #include <unistd.h>
  28 #include <nettle/des.h>
  29
  30 #if defined (__FreeBSD__)
  31 #include <rpc/des_crypt.h>
  32 #endif
  33
  34 #include <glib.h>
  35
  36 #include "passcrypt.h"
  37
  38 static void crypt_cfb_buf(const char key[8], unsigned char *buf, unsigned len,
  39                    unsigned chunksize, int decrypt);
  40
  41 void passcrypt_encrypt(gchar *password, guint len)
  42 {
  43         crypt_cfb_buf(PASSCRYPT_KEY, password, len, 1, 0 );
  44 }
  45
  46 void passcrypt_decrypt(gchar *password, guint len)
  47 {
  48         crypt_cfb_buf(PASSCRYPT_KEY, password, len, 1, 1 );
  49 }
  50
  51 /*
  52 * crypt_cfb_iv is the intermediate vector used for cypher feedback encryption
  53 */
  54 unsigned char crypt_cfb_iv[64];
  55 int crypt_cfb_blocksize = 8;    /* 8 for DES */
  56
  57 #if defined (__FreeBSD__)
  58 static void
  59 crypt_cfb_buf(const char key[8], unsigned char *buf, unsigned len,
  60               unsigned chunksize, int decrypt)
  61 {
  62         char des_key[8];
  63
  64         memcpy(des_key, PASSCRYPT_KEY, 8);
  65         des_setparity(des_key);
  66         if (decrypt)
  67                 ecb_crypt(des_key, buf, len, DES_DECRYPT);
  68         else
  69                 ecb_crypt(des_key, buf, len, DES_ENCRYPT);
  70 }
  71 #else
  72 static void crypt_cfb_shift(unsigned char *to,
  73                             const unsigned char *from, unsigned len);
  74 static void crypt_cfb_xor(unsigned char *to, const unsigned char *from,
  75                           unsigned len);
  76 static void crypt_unpack(unsigned char *a);
  77
  78 static void
  79 crypt_cfb_buf(const char key[8], unsigned char *buf, unsigned len,
  80               unsigned chunksize, int decrypt)
  81 {
  82         struct des_ctx ctx;
  83         unsigned char temp[64];
  84
  85         des_set_key(&ctx,(const uint8_t*) key);
  86         memset(temp, 0, sizeof(temp));
  87
  88         memset(crypt_cfb_iv, 0, sizeof(crypt_cfb_iv));
  89
  90         if (chunksize > crypt_cfb_blocksize)
  91                 chunksize = crypt_cfb_blocksize;
  92
  93         while (len) {
  94                 memcpy(temp, crypt_cfb_iv, sizeof(temp));
  95                 /* simulate encrypt() via Nettle */
  96                 char temp2[8];
  97                 memset(temp2,0,sizeof(temp2));
  98                 crypt_cfb_xor(temp2,temp,sizeof(temp)/sizeof(temp2));
  99                 des_encrypt(&ctx,sizeof(temp2),(uint8_t*)temp2,(uint8_t*)temp2);
 100                 memcpy(temp,temp2,sizeof(temp2));
 101                 crypt_unpack(temp);
 102                 /* */
 103                 if (chunksize > len)
 104                         chunksize = len;
 105                 if (decrypt)
 106                         crypt_cfb_shift(crypt_cfb_iv, buf, chunksize);
 107                 crypt_cfb_xor((unsigned char *) buf, temp, chunksize);
 108                 if (!decrypt)
 109                         crypt_cfb_shift(crypt_cfb_iv, buf, chunksize);
 110                 len -= chunksize;
 111                 buf += chunksize;
 112         }
 113 }
 114
 115 /*
 116 * Shift len bytes from end of to buffer to beginning, then put len
 117 * bytes from from at the end.  Caution: the to buffer is unpacked,
 118 * but the from buffer is not.
 119 */
 120 static void
 121 crypt_cfb_shift(unsigned char *to, const unsigned char *from, unsigned len)
 122 {
 123         unsigned i;
 124         unsigned j;
 125         unsigned k;
 126
 127         if (len < crypt_cfb_blocksize) {
 128                 i = len * 8;
 129                 j = crypt_cfb_blocksize * 8;
 130                 for (k = i; k < j; k++) {
 131                         to[0] = to[i];
 132                         ++to;
 133                 }
 134         }
 135
 136         for (i = 0; i < len; i++) {
 137                 j = *from++;
 138                 for (k = 0x80; k; k >>= 1)
 139                         *to++ = ((j & k) != 0);
 140         }
 141 }
 142
 143 /*
 144 * XOR len bytes from from into the data at to.  Caution: the from buffer
 145 * is unpacked, but the to buffer is not.
 146 */
 147 static void
 148 crypt_cfb_xor(unsigned char *to, const unsigned char *from, unsigned len)
 149 {
 150         unsigned i;
 151         unsigned j;
 152         unsigned char c;
 153
 154         for (i = 0; i < len; i++) {
 155                 c = 0;
 156                 for (j = 0; j < 8; j++)
 157                         c = (c << 1) | *from++;
 158                 *to++ ^= c;
 159         }
 160 }
 161
 162 /*
 163 * Take the 8-byte array at *a (must be able to hold 64 bytes!) and unpack
 164 * each bit into its own byte.
 165 */
 166 static void crypt_unpack(unsigned char *a)
 167 {
 168         int i, j;
 169
 170         for (i = 7; i >= 0; --i)
 171                 for (j = 7; j >= 0; --j)
 172                         a[(i << 3) + j] = (a[i] & (0x80 >> j)) != 0;
 173 }
 174 #endif