dlls/rsaenh/rc2.c

   1 /*
   2  * dlls/rsaen/rc2.c
   3  * RC2 functions
   4  *
   5  * Copyright 2004 Michael Jung
   6  * Based on public domain code by Tom St Denis (tomstdenis@iahu.ca)
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  21  */
  22
  23 /*
  24  * This file contains code from the LibTomCrypt cryptographic
  25  * library written by Tom St Denis (tomstdenis@iahu.ca). LibTomCrypt
  26  * is in the public domain. The code in this file is tailored to
  27  * special requirements. Take a look at http://libtomcrypt.org for the
  28  * original version.
  29  */
  30
  31 #include "tomcrypt.h"
  32
  33 /* 256-entry permutation table, probably derived somehow from pi */
  34 static const unsigned char permute[256] = {
  35         217,120,249,196, 25,221,181,237, 40,233,253,121, 74,160,216,157,
  36         198,126, 55,131, 43,118, 83,142, 98, 76,100,136, 68,139,251,162,
  37          23,154, 89,245,135,179, 79, 19, 97, 69,109,141,  9,129,125, 50,
  38         189,143, 64,235,134,183,123, 11,240,149, 33, 34, 92,107, 78,130,
  39          84,214,101,147,206, 96,178, 28,115, 86,192, 20,167,140,241,220,
  40          18,117,202, 31, 59,190,228,209, 66, 61,212, 48,163, 60,182, 38,
  41         111,191, 14,218, 70,105,  7, 87, 39,242, 29,155,188,148, 67,  3,
  42         248, 17,199,246,144,239, 62,231,  6,195,213, 47,200,102, 30,215,
  43           8,232,234,222,128, 82,238,247,132,170,114,172, 53, 77,106, 42,
  44         150, 26,210,113, 90, 21, 73,116, 75,159,208, 94,  4, 24,164,236,
  45         194,224, 65,110, 15, 81,203,204, 36,145,175, 80,161,244,112, 57,
  46         153,124, 58,133, 35,184,180,122,252,  2, 54, 91, 37, 85,151, 49,
  47          45, 93,250,152,227,138,146,174,  5,223, 41, 16,103,108,186,201,
  48         211,  0,230,207,225,158,168, 44, 99, 22,  1, 63, 88,226,137,169,
  49          13, 56, 52, 27,171, 51,255,176,187, 72, 12, 95,185,177,205, 46,
  50         197,243,219, 71,229,165,156,119, 10,166, 32,104,254,127,193,173
  51 };
  52
  53 int rc2_setup(const unsigned char *key, int keylen, int bits, int rounds, rc2_key *rc2)
  54 {
  55    unsigned *xkey = rc2->xkey;
  56    unsigned char tmp[128];
  57    unsigned T8, TM;
  58    int i;
  59
  60    if (keylen < 5 || keylen > 128) {
  61       return CRYPT_INVALID_KEYSIZE;
  62    }
  63
  64    if (rounds != 0 && rounds != 16) {
  65       return CRYPT_INVALID_ROUNDS;
  66    }
  67
  68     /* Following comment is from Eric Young's rc2 code: */
  69     /* It has come to my attention that there are 2 versions of the RC2
  70      * key schedule.  One which is normal, and anther which has a hook to
  71      * use a reduced key length.
  72      * BSAFE uses the 'retarded' version.  What I previously shipped is
  73      * the same as specifying 1024 for the 'bits' parameter.  BSAFE uses
  74      * a version where the bits parameter is the same as len*8 */
  75     /* Seems like MS uses the 'retarded' version, too.
  76      * Adjust effective keylen bits */
  77    if (bits <= 0) bits = keylen << 3;
  78    if (bits > 1024) bits = 1024;
  79
  80    for (i = 0; i < keylen; i++) {
  81        tmp[i] = key[i] & 255;
  82    }
  83
  84     /* Phase 1: Expand input key to 128 bytes */
  85     if (keylen < 128) {
  86         for (i = keylen; i < 128; i++) {
  87             tmp[i] = permute[(tmp[i - 1] + tmp[i - keylen]) & 255];
  88         }
  89     }
  90
  91     /* Phase 2 - reduce effective key size to "bits" */
  92     /*bits = keylen<<3; */
  93     T8   = (unsigned)(bits+7)>>3;
  94     TM   = (255 >> (unsigned)(7 & -bits));
  95     tmp[128 - T8] = permute[tmp[128 - T8] & TM];
  96     for (i = 127 - T8; i >= 0; i--) {
  97         tmp[i] = permute[tmp[i + 1] ^ tmp[i + T8]];
  98     }
  99
 100     /* Phase 3 - copy to xkey in little-endian order */
 101     for (i = 0; i < 64; i++) {
 102         xkey[i] =  (unsigned)tmp[2*i] + ((unsigned)tmp[2*i+1] << 8);
 103     }
 104
 105     return CRYPT_OK;
 106 }
 107
 108 /**********************************************************************\
 109 * Encrypt an 8-byte block of plaintext using the given key.            *
 110 \**********************************************************************/
 111 void rc2_ecb_encrypt( const unsigned char *plain,
 112                             unsigned char *cipher,
 113                             rc2_key *rc2)
 114 {
 115     unsigned *xkey;
 116     unsigned x76, x54, x32, x10, i;
 117
 118     xkey = rc2->xkey;
 119
 120     x76 = ((unsigned)plain[7] << 8) + (unsigned)plain[6];
 121     x54 = ((unsigned)plain[5] << 8) + (unsigned)plain[4];
 122     x32 = ((unsigned)plain[3] << 8) + (unsigned)plain[2];
 123     x10 = ((unsigned)plain[1] << 8) + (unsigned)plain[0];
 124
 125     for (i = 0; i < 16; i++) {
 126         x10 = (x10 + (x32 & ~x76) + (x54 & x76) + xkey[4*i+0]) & 0xFFFF;
 127         x10 = ((x10 << 1) | (x10 >> 15));
 128
 129         x32 = (x32 + (x54 & ~x10) + (x76 & x10) + xkey[4*i+1]) & 0xFFFF;
 130         x32 = ((x32 << 2) | (x32 >> 14));
 131
 132         x54 = (x54 + (x76 & ~x32) + (x10 & x32) + xkey[4*i+2]) & 0xFFFF;
 133         x54 = ((x54 << 3) | (x54 >> 13));
 134
 135         x76 = (x76 + (x10 & ~x54) + (x32 & x54) + xkey[4*i+3]) & 0xFFFF;
 136         x76 = ((x76 << 5) | (x76 >> 11));
 137
 138         if (i == 4 || i == 10) {
 139             x10 = (x10 + xkey[x76 & 63]) & 0xFFFF;
 140             x32 = (x32 + xkey[x10 & 63]) & 0xFFFF;
 141             x54 = (x54 + xkey[x32 & 63]) & 0xFFFF;
 142             x76 = (x76 + xkey[x54 & 63]) & 0xFFFF;
 143         }
 144     }
 145
 146     cipher[0] = (unsigned char)x10;
 147     cipher[1] = (unsigned char)(x10 >> 8);
 148     cipher[2] = (unsigned char)x32;
 149     cipher[3] = (unsigned char)(x32 >> 8);
 150     cipher[4] = (unsigned char)x54;
 151     cipher[5] = (unsigned char)(x54 >> 8);
 152     cipher[6] = (unsigned char)x76;
 153     cipher[7] = (unsigned char)(x76 >> 8);
 154 }
 155
 156 /**********************************************************************\
 157 * Decrypt an 8-byte block of ciphertext using the given key.           *
 158 \**********************************************************************/
 159 void rc2_ecb_decrypt( const unsigned char *cipher,
 160                             unsigned char *plain,
 161                             rc2_key *rc2)
 162 {
 163     unsigned x76, x54, x32, x10;
 164     unsigned *xkey;
 165     int i;
 166
 167     xkey = rc2->xkey;
 168
 169     x76 = ((unsigned)cipher[7] << 8) + (unsigned)cipher[6];
 170     x54 = ((unsigned)cipher[5] << 8) + (unsigned)cipher[4];
 171     x32 = ((unsigned)cipher[3] << 8) + (unsigned)cipher[2];
 172     x10 = ((unsigned)cipher[1] << 8) + (unsigned)cipher[0];
 173
 174     for (i = 15; i >= 0; i--) {
 175         if (i == 4 || i == 10) {
 176             x76 = (x76 - xkey[x54 & 63]) & 0xFFFF;
 177             x54 = (x54 - xkey[x32 & 63]) & 0xFFFF;
 178             x32 = (x32 - xkey[x10 & 63]) & 0xFFFF;
 179             x10 = (x10 - xkey[x76 & 63]) & 0xFFFF;
 180         }
 181
 182         x76 = ((x76 << 11) | (x76 >> 5));
 183         x76 = (x76 - ((x10 & ~x54) + (x32 & x54) + xkey[4*i+3])) & 0xFFFF;
 184
 185         x54 = ((x54 << 13) | (x54 >> 3));
 186         x54 = (x54 - ((x76 & ~x32) + (x10 & x32) + xkey[4*i+2])) & 0xFFFF;
 187
 188         x32 = ((x32 << 14) | (x32 >> 2));
 189         x32 = (x32 - ((x54 & ~x10) + (x76 & x10) + xkey[4*i+1])) & 0xFFFF;
 190
 191         x10 = ((x10 << 15) | (x10 >> 1));
 192         x10 = (x10 - ((x32 & ~x76) + (x54 & x76) + xkey[4*i+0])) & 0xFFFF;
 193     }
 194
 195     plain[0] = (unsigned char)x10;
 196     plain[1] = (unsigned char)(x10 >> 8);
 197     plain[2] = (unsigned char)x32;
 198     plain[3] = (unsigned char)(x32 >> 8);
 199     plain[4] = (unsigned char)x54;
 200     plain[5] = (unsigned char)(x54 >> 8);
 201     plain[6] = (unsigned char)x76;
 202     plain[7] = (unsigned char)(x76 >> 8);
 203 }