skipjack.c

   1 /* skipjack.c */
   2 /*
   3     This file is part of the Crypto-avr-lib/microcrypt-lib.
   4     Copyright (C) 2008  Daniel Otte (daniel.otte@rub.de)
   5
   6     This program is free software: you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation, either version 3 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19 /**
  20  *
  21  *
  22  *
  23  *
  24  *
  25  *
  26  */
  27
  28
  29 #include <stdint.h>
  30 #include <avr/io.h>
  31 #include <avr/pgmspace.h>
  32
  33 #define SKIPJACK_CNT_BIG
  34
  35 #ifdef SKIPJACK_CNT_BIG
  36   #define SKIPJACK_CNT_SHIFT <<8
  37 #else
  38   #define SKIPJACK_CNT_SHIFT
  39 #endif
  40
  41 /*****************************************************************************/
  42
  43 uint8_t skipjack_ftable[] PROGMEM ={
  44         0xa3, 0xd7, 0x09, 0x83, 0xf8, 0x48, 0xf6, 0xf4,
  45         0xb3, 0x21, 0x15, 0x78, 0x99, 0xb1, 0xaf, 0xf9,
  46         0xe7, 0x2d, 0x4d, 0x8a, 0xce, 0x4c, 0xca, 0x2e,
  47         0x52, 0x95, 0xd9, 0x1e, 0x4e, 0x38, 0x44, 0x28,
  48         0x0a, 0xdf, 0x02, 0xa0, 0x17, 0xf1, 0x60, 0x68,
  49         0x12, 0xb7, 0x7a, 0xc3, 0xe9, 0xfa, 0x3d, 0x53,
  50         0x96, 0x84, 0x6b, 0xba, 0xf2, 0x63, 0x9a, 0x19,
  51         0x7c, 0xae, 0xe5, 0xf5, 0xf7, 0x16, 0x6a, 0xa2,
  52         0x39, 0xb6, 0x7b, 0x0f, 0xc1, 0x93, 0x81, 0x1b,
  53         0xee, 0xb4, 0x1a, 0xea, 0xd0, 0x91, 0x2f, 0xb8,
  54         0x55, 0xb9, 0xda, 0x85, 0x3f, 0x41, 0xbf, 0xe0,
  55         0x5a, 0x58, 0x80, 0x5f, 0x66, 0x0b, 0xd8, 0x90,
  56         0x35, 0xd5, 0xc0, 0xa7, 0x33, 0x06, 0x65, 0x69,
  57         0x45, 0x00, 0x94, 0x56, 0x6d, 0x98, 0x9b, 0x76,
  58         0x97, 0xfc, 0xb2, 0xc2, 0xb0, 0xfe, 0xdb, 0x20,
  59         0xe1, 0xeb, 0xd6, 0xe4, 0xdd, 0x47, 0x4a, 0x1d,
  60         0x42, 0xed, 0x9e, 0x6e, 0x49, 0x3c, 0xcd, 0x43,
  61         0x27, 0xd2, 0x07, 0xd4, 0xde, 0xc7, 0x67, 0x18,
  62         0x89, 0xcb, 0x30, 0x1f, 0x8d, 0xc6, 0x8f, 0xaa,
  63         0xc8, 0x74, 0xdc, 0xc9, 0x5d, 0x5c, 0x31, 0xa4,
  64         0x70, 0x88, 0x61, 0x2c, 0x9f, 0x0d, 0x2b, 0x87,
  65         0x50, 0x82, 0x54, 0x64, 0x26, 0x7d, 0x03, 0x40,
  66         0x34, 0x4b, 0x1c, 0x73, 0xd1, 0xc4, 0xfd, 0x3b,
  67         0xcc, 0xfb, 0x7f, 0xab, 0xe6, 0x3e, 0x5b, 0xa5,
  68         0xad, 0x04, 0x23, 0x9c, 0x14, 0x51, 0x22, 0xf0,
  69         0x29, 0x79, 0x71, 0x7e, 0xff, 0x8c, 0x0e, 0xe2,
  70         0x0c, 0xef, 0xbc, 0x72, 0x75, 0x6f, 0x37, 0xa1,
  71         0xec, 0xd3, 0x8e, 0x62, 0x8b, 0x86, 0x10, 0xe8,
  72         0x08, 0x77, 0x11, 0xbe, 0x92, 0x4f, 0x24, 0xc5,
  73         0x32, 0x36, 0x9d, 0xcf, 0xf3, 0xa6, 0xbb, 0xac,
  74         0x5e, 0x6c, 0xa9, 0x13, 0x57, 0x25, 0xb5, 0xe3,
  75         0xbd, 0xa8, 0x3a, 0x01, 0x05, 0x59, 0x2a, 0x46
  76 };
  77
  78 /*****************************************************************************/
  79
  80 uint16_t skipjack_g(uint16_t g, uint8_t k, uint8_t *key){
  81         #define G1 (((uint8_t*)&g)[0])
  82         #define G2 (((uint8_t*)&g)[1])
  83         /* this could also be rolled up */
  84         G1 ^= pgm_read_byte_near(&(skipjack_ftable[G2 ^ key[(4*k+0)%10]]));
  85         G2 ^= pgm_read_byte_near(&(skipjack_ftable[G1 ^ key[(4*k+1)%10]]));
  86         G1 ^= pgm_read_byte_near(&(skipjack_ftable[G2 ^ key[(4*k+2)%10]]));
  87         G2 ^= pgm_read_byte_near(&(skipjack_ftable[G1 ^ key[(4*k+3)%10]]));
  88         return g;
  89 }
  90
  91 /*****************************************************************************/
  92
  93 uint16_t skipjack_g_inv(uint16_t g, uint8_t k, uint8_t *key){
  94 //      #define G1 (((uint8_t)&g)[1])
  95 //      #define G2 (((uint8_t)&g)[0])
  96         /* this could also be rolled up */
  97         G2 ^= pgm_read_byte_near(&(skipjack_ftable[G1 ^ key[(4*k+3)%10]]));
  98         G1 ^= pgm_read_byte_near(&(skipjack_ftable[G2 ^ key[(4*k+2)%10]]));
  99         G2 ^= pgm_read_byte_near(&(skipjack_ftable[G1 ^ key[(4*k+1)%10]]));
 100         G1 ^= pgm_read_byte_near(&(skipjack_ftable[G2 ^ key[(4*k+0)%10]]));
 101         return g;
 102 }
 103
 104 /*****************************************************************************/
 105
 106 void skipjack_a(uint16_t* w, uint8_t k, uint8_t* key){
 107         uint16_t t;
 108
 109         t = w[3];
 110         w[3] = w[2];
 111         w[2] = w[1];
 112         w[1] = skipjack_g(w[0],k-1,key);
 113         w[0] = t ^ w[1] ^ (((uint16_t)k)SKIPJACK_CNT_SHIFT);
 114 }
 115
 116 /*****************************************************************************/
 117
 118 void skipjack_a_inv(uint16_t* w, uint8_t k, uint8_t* key){
 119         uint16_t t;
 120         t = w[0] ^ w[1];
 121         w[0] = skipjack_g_inv(w[1],k-1,key);
 122         w[1] = w[2];
 123         w[2] = w[3];
 124         w[3] = t ^ (((uint16_t)k)SKIPJACK_CNT_SHIFT);
 125 }
 126
 127 /*****************************************************************************/
 128
 129 void skipjack_b(uint16_t* w, uint8_t k, uint8_t* key){
 130         uint16_t t;
 131         t = w[0];
 132         w[0] = w[3];
 133         w[3] = w[2];
 134         w[2] = t ^ (((uint16_t)k)SKIPJACK_CNT_SHIFT) ^ w[1];
 135         w[1] = skipjack_g(t,k-1,key);
 136 }
 137
 138 /*****************************************************************************/
 139
 140 void skipjack_b_inv(uint16_t* w, uint8_t k, uint8_t* key){
 141         uint16_t t;
 142         t = w[2];
 143         w[2] = w[3];
 144         w[3] = w[0];
 145         w[0] = skipjack_g_inv(w[1],k-1,key);
 146         w[1] = w[0] ^ t ^ (((uint16_t)k)SKIPJACK_CNT_SHIFT);
 147 }
 148
 149 /*****************************************************************************/
 150 /**
 151  * block is 64 bits (=8 bytes) in size, key is 80 bits (=10 bytes) in size.
 152  *
 153  */
 154 void skipjack_enc(void* block, void* key){
 155         uint8_t k;
 156         for(k=0; k<32; ++k){
 157                 if(k & 0x08){
 158                         skipjack_b((uint16_t*)block, k+1, key);
 159                 } else {
 160                         skipjack_a((uint16_t*)block, k+1, key);
 161                 }
 162         }
 163 }
 164
 165 /*****************************************************************************/
 166 /**
 167  * block is 64 bits (=8 bytes) in size, key is 80 bits (=10 bytes) in size.
 168  *
 169  */
 170 void skipjack_dec(void* block, void* key){
 171         int8_t k;
 172         for(k=31; k>=0; --k){
 173                 if(k & 0x08){
 174                         skipjack_b_inv((uint16_t*)block, k+1, key);
 175                 } else {
 176                         skipjack_a_inv((uint16_t*)block, k+1, key);
 177                 }
 178         }
 179 }
 180
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