skipjack.c

   1 /**
   2  *
   3  *
   4  *
   5  *
   6  *
   7  *
   8  */
   9
  10
  11 #include <stdint.h>
  12 #include <avr/io.h>
  13 #include <avr/pgmspace.h>
  14
  15 /*****************************************************************************/
  16
  17 uint8_t skipjack_ftable[] PROGMEM ={
  18         0xa3, 0xd7, 0x09, 0x83, 0xf8, 0x48, 0xf6, 0xf4,
  19         0xb3, 0x21, 0x15, 0x78, 0x99, 0xb1, 0xaf, 0xf9,
  20         0xe7, 0x2d, 0x4d, 0x8a, 0xce, 0x4c, 0xca, 0x2e,
  21         0x52, 0x95, 0xd9, 0x1e, 0x4e, 0x38, 0x44, 0x28,
  22         0x0a, 0xdf, 0x02, 0xa0, 0x17, 0xf1, 0x60, 0x68,
  23         0x12, 0xb7, 0x7a, 0xc3, 0xe9, 0xfa, 0x3d, 0x53,
  24         0x96, 0x84, 0x6b, 0xba, 0xf2, 0x63, 0x9a, 0x19,
  25         0x7c, 0xae, 0xe5, 0xf5, 0xf7, 0x16, 0x6a, 0xa2,
  26         0x39, 0xb6, 0x7b, 0x0f, 0xc1, 0x93, 0x81, 0x1b,
  27         0xee, 0xb4, 0x1a, 0xea, 0xd0, 0x91, 0x2f, 0xb8,
  28         0x55, 0xb9, 0xda, 0x85, 0x3f, 0x41, 0xbf, 0xe0,
  29         0x5a, 0x58, 0x80, 0x5f, 0x66, 0x0b, 0xd8, 0x90,
  30         0x35, 0xd5, 0xc0, 0xa7, 0x33, 0x06, 0x65, 0x69,
  31         0x45, 0x00, 0x94, 0x56, 0x6d, 0x98, 0x9b, 0x76,
  32         0x97, 0xfc, 0xb2, 0xc2, 0xb0, 0xfe, 0xdb, 0x20,
  33         0xe1, 0xeb, 0xd6, 0xe4, 0xdd, 0x47, 0x4a, 0x1d,
  34         0x42, 0xed, 0x9e, 0x6e, 0x49, 0x3c, 0xcd, 0x43,
  35         0x27, 0xd2, 0x07, 0xd4, 0xde, 0xc7, 0x67, 0x18,
  36         0x89, 0xcb, 0x30, 0x1f, 0x8d, 0xc6, 0x8f, 0xaa,
  37         0xc8, 0x74, 0xdc, 0xc9, 0x5d, 0x5c, 0x31, 0xa4,
  38         0x70, 0x88, 0x61, 0x2c, 0x9f, 0x0d, 0x2b, 0x87,
  39         0x50, 0x82, 0x54, 0x64, 0x26, 0x7d, 0x03, 0x40,
  40         0x34, 0x4b, 0x1c, 0x73, 0xd1, 0xc4, 0xfd, 0x3b,
  41         0xcc, 0xfb, 0x7f, 0xab, 0xe6, 0x3e, 0x5b, 0xa5,
  42         0xad, 0x04, 0x23, 0x9c, 0x14, 0x51, 0x22, 0xf0,
  43         0x29, 0x79, 0x71, 0x7e, 0xff, 0x8c, 0x0e, 0xe2,
  44         0x0c, 0xef, 0xbc, 0x72, 0x75, 0x6f, 0x37, 0xa1,
  45         0xec, 0xd3, 0x8e, 0x62, 0x8b, 0x86, 0x10, 0xe8,
  46         0x08, 0x77, 0x11, 0xbe, 0x92, 0x4f, 0x24, 0xc5,
  47         0x32, 0x36, 0x9d, 0xcf, 0xf3, 0xa6, 0xbb, 0xac,
  48         0x5e, 0x6c, 0xa9, 0x13, 0x57, 0x25, 0xb5, 0xe3,
  49         0xbd, 0xa8, 0x3a, 0x01, 0x05, 0x59, 0x2a, 0x46
  50 };
  51
  52 /*****************************************************************************/
  53
  54 uint16_t skipjack_g(uint16_t g, uint8_t k, uint8_t *key){
  55         #define G1 (((uint8_t*)&g)[0])
  56         #define G2 (((uint8_t*)&g)[1])
  57         /* this could also be rolled up */
  58         G1 ^= pgm_read_byte_near(&(skipjack_ftable[G2 ^ key[(4*k+0)%10]]));
  59         G2 ^= pgm_read_byte_near(&(skipjack_ftable[G1 ^ key[(4*k+1)%10]]));
  60         G1 ^= pgm_read_byte_near(&(skipjack_ftable[G2 ^ key[(4*k+2)%10]]));
  61         G2 ^= pgm_read_byte_near(&(skipjack_ftable[G1 ^ key[(4*k+3)%10]]));
  62         return g;
  63 }
  64
  65 /*****************************************************************************/
  66
  67 uint16_t skipjack_g_inv(uint16_t g, uint8_t k, uint8_t *key){
  68 //      #define G1 (((uint8_t)&g)[1])
  69 //      #define G2 (((uint8_t)&g)[0])
  70         /* this could also be rolled up */
  71         G2 ^= pgm_read_byte_near(&(skipjack_ftable[G1 ^ key[(4*k+3)%10]]));
  72         G1 ^= pgm_read_byte_near(&(skipjack_ftable[G2 ^ key[(4*k+2)%10]]));
  73         G2 ^= pgm_read_byte_near(&(skipjack_ftable[G1 ^ key[(4*k+1)%10]]));
  74         G1 ^= pgm_read_byte_near(&(skipjack_ftable[G2 ^ key[(4*k+0)%10]]));
  75         return g;
  76 }
  77
  78 /*****************************************************************************/
  79
  80 void skipjack_a(uint16_t* w, uint8_t k, uint8_t* key){
  81         uint16_t t;
  82
  83         t = w[3];
  84         w[3] = w[2];
  85         w[2] = w[1];
  86         w[1] = skipjack_g(w[0],k-1,key);
  87         w[0] = t ^ w[1] ^ k<<8;
  88 }
  89
  90 /*****************************************************************************/
  91
  92 void skipjack_a_inv(uint16_t* w, uint8_t k, uint8_t* key){
  93         uint16_t t;
  94         t = w[0] ^ w[1];
  95         w[0] = skipjack_g_inv(w[1],k-1,key);
  96         w[1] = w[2];
  97         w[2] = w[3];
  98         w[3] = t ^ k<<8;
  99 }
 100
 101 /*****************************************************************************/
 102
 103 void skipjack_b(uint16_t* w, uint8_t k, uint8_t* key){
 104         uint16_t t;
 105         t = w[0];
 106         w[0] = w[3];
 107         w[3] = w[2];
 108         w[2] = t ^ k<<8 ^ w[1];
 109         w[1] = skipjack_g(t,k-1,key);
 110 }
 111
 112 /*****************************************************************************/
 113
 114 void skipjack_b_inv(uint16_t* w, uint8_t k, uint8_t* key){
 115         uint16_t t;
 116         t = w[2];
 117         w[2] = w[3];
 118         w[3] = w[0];
 119         w[0] = skipjack_g_inv(w[1],k-1,key);
 120         w[1] = w[0] ^ t ^ k<<8;
 121 }
 122
 123 /*****************************************************************************/
 124 /**
 125  * block is 64 bits (=8 bytes) in size, key is 80 bits (=10 bytes) in size.
 126  *
 127  */
 128 void skipjack_enc(void* block, void* key){
 129         uint8_t k;
 130         for(k=0; k<32; ++k){
 131                 if(k & 0x08){
 132                         skipjack_b((uint16_t*)block, k+1, key);
 133                 } else {
 134                         skipjack_a((uint16_t*)block, k+1, key);
 135                 }
 136         }
 137 }
 138
 139 /*****************************************************************************/
 140 /**
 141  * block is 64 bits (=8 bytes) in size, key is 80 bits (=10 bytes) in size.
 142  *
 143  */
 144 void skipjack_dec(void* block, void* key){
 145         int8_t k;
 146         for(k=31; k>=0; --k){
 147                 if(k & 0x08){
 148                         skipjack_b_inv((uint16_t*)block, k+1, key);
 149                 } else {
 150                         skipjack_a_inv((uint16_t*)block, k+1, key);
 151                 }
 152         }
 153 }
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