serpent-sboxes.c

   1 /* serpent-sboxes.c
   2  * a non-bitsliced implementation of the serpent sboxes
   3  * author: Daniel Otte
   4  * email:  daniel.otte@rub.de
   5  * license: GPLv3
   6  */
   7
   8 #include <stdint.h>
   9 #include <string.h> /* memset() */
  10 #include <avr/pgmspace.h>
  11 #include "serpent-sboxes.h"
  12
  13 uint8_t sbox[] PROGMEM = {
  14  0x38, 0xF1, 0xA6, 0x5B, 0xED, 0x42, 0x70, 0x9C,
  15  0xFC, 0x27, 0x90, 0x5A, 0x1B, 0xE8, 0x6D, 0x34,
  16  0x86, 0x79, 0x3C, 0xAF, 0xD1, 0xE4, 0x0B, 0x52,
  17  0x0F, 0xB8, 0xC9, 0x63, 0xD1, 0x24, 0xA7, 0x5E,
  18  0x1F, 0x83, 0xC0, 0xB6, 0x25, 0x4A, 0x9E, 0x7D,
  19  0xF5, 0x2B, 0x4A, 0x9C, 0x03, 0xE8, 0xD6, 0x71,
  20  0x72, 0xC5, 0x84, 0x6B, 0xE9, 0x1F, 0xD3, 0xA0,
  21  0x1D, 0xF0, 0xE8, 0x2B, 0x74, 0xCA, 0x93, 0x56,
  22 /* now the inverted sboxes */
  23  0xD3, 0xB0, 0xA6, 0x5C, 0x1E, 0x47, 0xF9, 0x82,
  24  0x58, 0x2E, 0xF6, 0xC3, 0xB4, 0x79, 0x1D, 0xA0,
  25  0xC9, 0xF4, 0xBE, 0x12, 0x03, 0x6D, 0x58, 0xA7,
  26  0x09, 0xA7, 0xBE, 0x6D, 0x35, 0xC2, 0x48, 0xF1,
  27  0x50, 0x83, 0xA9, 0x7E, 0x2C, 0xB6, 0x4F, 0xD1,
  28  0x8F, 0x29, 0x41, 0xDE, 0xB6, 0x53, 0x7C, 0xA0,
  29  0xFA, 0x1D, 0x53, 0x60, 0x49, 0xE7, 0x2C, 0x8B,
  30  0x30, 0x6D, 0x9E, 0xF8, 0x5C, 0xB7, 0xA1, 0x42
  31 };
  32
  33
  34 #define SHR_O(a) c=(a)&1; ((a) = (a)>>1)
  35 #define SHR_I(a) ((a) = (c?0x80:0x00)| ((a)>>1))
  36
  37 static void ip(uint8_t *o, uint32_t *i){
  38         uint8_t c; // carry
  39         uint8_t n,m;
  40         memset(o, 0, 16);
  41         for(n=0; n<16; ++n){
  42                 for(m=0; m<2; ++m){
  43                 SHR_O(i[0]);
  44                 SHR_I(o[n]);
  45                 SHR_O(i[1]);
  46                 SHR_I(o[n]);
  47                 SHR_O(i[2]);
  48                 SHR_I(o[n]);
  49                 SHR_O(i[3]);
  50                 SHR_I(o[n]);
  51                 }
  52         }
  53 }
  54
  55 #undef SHR_I
  56 #define SHR_I(a) ((a) = (c?0x80000000L:0x00L)| ((a)>>1)) /* we use 32-bit words here */
  57
  58
  59 static void fp(uint32_t *o, uint32_t *i){
  60         uint8_t c; // carry
  61         uint8_t n,m;
  62         memset(o, 0, 16);
  63         for(n=0; n<4; ++n){
  64                 for(m=0; m<8; ++m){
  65                 SHR_O(i[n]);
  66                 SHR_I(o[0]);
  67                 SHR_O(i[n]);
  68                 SHR_I(o[1]);
  69                 SHR_O(i[n]);
  70                 SHR_I(o[2]);
  71                 SHR_O(i[n]);
  72                 SHR_I(o[3]);
  73                 }
  74         }
  75 }
  76
  77 /******************************************************************************/
  78
  79 static void sbox128x(uint8_t box, void* w){
  80         uint8_t sb[16];
  81         uint8_t i,t,x;
  82         box &= 0x0f;
  83         /* load sbox */
  84         for(i=0; i<8; ++i){
  85                 t = pgm_read_byte(sbox + box*8 + i);
  86                 sb[2*i+0]=t>>4;
  87                 sb[2*i+1]=t&0xf;
  88         }
  89         uint8_t o[16];
  90         ip(o, w);
  91
  92         for(i=0; i<16; ++i){
  93                 t = ((uint8_t*)o)[i];
  94                 x = sb[t>>4];
  95                 x <<= 4;
  96                 x |= sb[t&0xf];
  97                 ((uint8_t*)o)[i] = x;
  98         }
  99         fp(w, (uint32_t*)o);
 100 }
 101
 102 void sbox128(void * w, uint8_t box){
 103         sbox128x(box&0x7, w);
 104 }
 105
 106 void inv_sbox128(void * w, uint8_t box){
 107         sbox128x(((box&0x7)|0x8), w);
 108 }