cast.c

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    1 /*      $FreeBSD: releng/5.1/sys/opencrypto/cast.c 104476 2002-10-04 20:31:23Z sam $    */
    2 /*      $OpenBSD: cast.c,v 1.2 2000/06/06 06:49:47 deraadt Exp $       */
    3 
    4 /*
    5  *      CAST-128 in C
    6  *      Written by Steve Reid <sreid@sea-to-sky.net>
    7  *      100% Public Domain - no warranty
    8  *      Released 1997.10.11
    9  */
   10 
   11 #include <sys/types.h>
   12 #include <opencrypto/cast.h>
   13 #include <opencrypto/castsb.h>
   14 
   15 /* Macros to access 8-bit bytes out of a 32-bit word */
   16 #define U_INT8_Ta(x) ( (u_int8_t) (x>>24) )
   17 #define U_INT8_Tb(x) ( (u_int8_t) ((x>>16)&255) )
   18 #define U_INT8_Tc(x) ( (u_int8_t) ((x>>8)&255) )
   19 #define U_INT8_Td(x) ( (u_int8_t) ((x)&255) )
   20 
   21 /* Circular left shift */
   22 #define ROL(x, n) ( ((x)<<(n)) | ((x)>>(32-(n))) )
   23 
   24 /* CAST-128 uses three different round functions */
   25 #define F1(l, r, i) \
   26         t = ROL(key->xkey[i] + r, key->xkey[i+16]); \
   27         l ^= ((cast_sbox1[U_INT8_Ta(t)] ^ cast_sbox2[U_INT8_Tb(t)]) - \
   28          cast_sbox3[U_INT8_Tc(t)]) + cast_sbox4[U_INT8_Td(t)];
   29 #define F2(l, r, i) \
   30         t = ROL(key->xkey[i] ^ r, key->xkey[i+16]); \
   31         l ^= ((cast_sbox1[U_INT8_Ta(t)] - cast_sbox2[U_INT8_Tb(t)]) + \
   32          cast_sbox3[U_INT8_Tc(t)]) ^ cast_sbox4[U_INT8_Td(t)];
   33 #define F3(l, r, i) \
   34         t = ROL(key->xkey[i] - r, key->xkey[i+16]); \
   35         l ^= ((cast_sbox1[U_INT8_Ta(t)] + cast_sbox2[U_INT8_Tb(t)]) ^ \
   36          cast_sbox3[U_INT8_Tc(t)]) - cast_sbox4[U_INT8_Td(t)];
   37 
   38 
   39 /***** Encryption Function *****/
   40 
   41 void cast_encrypt(cast_key* key, u_int8_t* inblock, u_int8_t* outblock)
   42 {
   43 u_int32_t t, l, r;
   44 
   45         /* Get inblock into l,r */
   46         l = ((u_int32_t)inblock[0] << 24) | ((u_int32_t)inblock[1] << 16) |
   47          ((u_int32_t)inblock[2] << 8) | (u_int32_t)inblock[3];
   48         r = ((u_int32_t)inblock[4] << 24) | ((u_int32_t)inblock[5] << 16) |
   49          ((u_int32_t)inblock[6] << 8) | (u_int32_t)inblock[7];
   50         /* Do the work */
   51         F1(l, r,  0);
   52         F2(r, l,  1);
   53         F3(l, r,  2);
   54         F1(r, l,  3);
   55         F2(l, r,  4);
   56         F3(r, l,  5);
   57         F1(l, r,  6);
   58         F2(r, l,  7);
   59         F3(l, r,  8);
   60         F1(r, l,  9);
   61         F2(l, r, 10);
   62         F3(r, l, 11);
   63         /* Only do full 16 rounds if key length > 80 bits */
   64         if (key->rounds > 12) {
   65                 F1(l, r, 12);
   66                 F2(r, l, 13);
   67                 F3(l, r, 14);
   68                 F1(r, l, 15);
   69         }
   70         /* Put l,r into outblock */
   71         outblock[0] = U_INT8_Ta(r);
   72         outblock[1] = U_INT8_Tb(r);
   73         outblock[2] = U_INT8_Tc(r);
   74         outblock[3] = U_INT8_Td(r);
   75         outblock[4] = U_INT8_Ta(l);
   76         outblock[5] = U_INT8_Tb(l);
   77         outblock[6] = U_INT8_Tc(l);
   78         outblock[7] = U_INT8_Td(l);
   79         /* Wipe clean */
   80         t = l = r = 0;
   81 }
   82 
   83 
   84 /***** Decryption Function *****/
   85 
   86 void cast_decrypt(cast_key* key, u_int8_t* inblock, u_int8_t* outblock)
   87 {
   88 u_int32_t t, l, r;
   89 
   90         /* Get inblock into l,r */
   91         r = ((u_int32_t)inblock[0] << 24) | ((u_int32_t)inblock[1] << 16) |
   92          ((u_int32_t)inblock[2] << 8) | (u_int32_t)inblock[3];
   93         l = ((u_int32_t)inblock[4] << 24) | ((u_int32_t)inblock[5] << 16) |
   94          ((u_int32_t)inblock[6] << 8) | (u_int32_t)inblock[7];
   95         /* Do the work */
   96         /* Only do full 16 rounds if key length > 80 bits */
   97         if (key->rounds > 12) {
   98                 F1(r, l, 15);
   99                 F3(l, r, 14);
  100                 F2(r, l, 13);
  101                 F1(l, r, 12);
  102         }
  103         F3(r, l, 11);
  104         F2(l, r, 10);
  105         F1(r, l,  9);
  106         F3(l, r,  8);
  107         F2(r, l,  7);
  108         F1(l, r,  6);
  109         F3(r, l,  5);
  110         F2(l, r,  4);
  111         F1(r, l,  3);
  112         F3(l, r,  2);
  113         F2(r, l,  1);
  114         F1(l, r,  0);
  115         /* Put l,r into outblock */
  116         outblock[0] = U_INT8_Ta(l);
  117         outblock[1] = U_INT8_Tb(l);
  118         outblock[2] = U_INT8_Tc(l);
  119         outblock[3] = U_INT8_Td(l);
  120         outblock[4] = U_INT8_Ta(r);
  121         outblock[5] = U_INT8_Tb(r);
  122         outblock[6] = U_INT8_Tc(r);
  123         outblock[7] = U_INT8_Td(r);
  124         /* Wipe clean */
  125         t = l = r = 0;
  126 }
  127 
  128 
  129 /***** Key Schedual *****/
  130 
  131 void cast_setkey(cast_key* key, u_int8_t* rawkey, int keybytes)
  132 {
  133 u_int32_t t[4], z[4], x[4];
  134 int i;
  135 
  136         /* Set number of rounds to 12 or 16, depending on key length */
  137         key->rounds = (keybytes <= 10 ? 12 : 16);
  138 
  139         /* Copy key to workspace x */
  140         for (i = 0; i < 4; i++) {
  141                 x[i] = 0;
  142                 if ((i*4+0) < keybytes) x[i] = (u_int32_t)rawkey[i*4+0] << 24;
  143                 if ((i*4+1) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+1] << 16;
  144                 if ((i*4+2) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+2] << 8;
  145                 if ((i*4+3) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+3];
  146         }
  147         /* Generate 32 subkeys, four at a time */
  148         for (i = 0; i < 32; i+=4) {
  149                 switch (i & 4) {
  150                  case 0:
  151                         t[0] = z[0] = x[0] ^ cast_sbox5[U_INT8_Tb(x[3])] ^
  152                          cast_sbox6[U_INT8_Td(x[3])] ^ cast_sbox7[U_INT8_Ta(x[3])] ^
  153                          cast_sbox8[U_INT8_Tc(x[3])] ^ cast_sbox7[U_INT8_Ta(x[2])];
  154                         t[1] = z[1] = x[2] ^ cast_sbox5[U_INT8_Ta(z[0])] ^
  155                          cast_sbox6[U_INT8_Tc(z[0])] ^ cast_sbox7[U_INT8_Tb(z[0])] ^
  156                          cast_sbox8[U_INT8_Td(z[0])] ^ cast_sbox8[U_INT8_Tc(x[2])];
  157                         t[2] = z[2] = x[3] ^ cast_sbox5[U_INT8_Td(z[1])] ^
  158                          cast_sbox6[U_INT8_Tc(z[1])] ^ cast_sbox7[U_INT8_Tb(z[1])] ^
  159                          cast_sbox8[U_INT8_Ta(z[1])] ^ cast_sbox5[U_INT8_Tb(x[2])];
  160                         t[3] = z[3] = x[1] ^ cast_sbox5[U_INT8_Tc(z[2])] ^
  161                          cast_sbox6[U_INT8_Tb(z[2])] ^ cast_sbox7[U_INT8_Td(z[2])] ^
  162                          cast_sbox8[U_INT8_Ta(z[2])] ^ cast_sbox6[U_INT8_Td(x[2])];
  163                         break;
  164                  case 4:
  165                         t[0] = x[0] = z[2] ^ cast_sbox5[U_INT8_Tb(z[1])] ^
  166                          cast_sbox6[U_INT8_Td(z[1])] ^ cast_sbox7[U_INT8_Ta(z[1])] ^
  167                          cast_sbox8[U_INT8_Tc(z[1])] ^ cast_sbox7[U_INT8_Ta(z[0])];
  168                         t[1] = x[1] = z[0] ^ cast_sbox5[U_INT8_Ta(x[0])] ^
  169                          cast_sbox6[U_INT8_Tc(x[0])] ^ cast_sbox7[U_INT8_Tb(x[0])] ^
  170                          cast_sbox8[U_INT8_Td(x[0])] ^ cast_sbox8[U_INT8_Tc(z[0])];
  171                         t[2] = x[2] = z[1] ^ cast_sbox5[U_INT8_Td(x[1])] ^
  172                          cast_sbox6[U_INT8_Tc(x[1])] ^ cast_sbox7[U_INT8_Tb(x[1])] ^
  173                          cast_sbox8[U_INT8_Ta(x[1])] ^ cast_sbox5[U_INT8_Tb(z[0])];
  174                         t[3] = x[3] = z[3] ^ cast_sbox5[U_INT8_Tc(x[2])] ^
  175                          cast_sbox6[U_INT8_Tb(x[2])] ^ cast_sbox7[U_INT8_Td(x[2])] ^
  176                          cast_sbox8[U_INT8_Ta(x[2])] ^ cast_sbox6[U_INT8_Td(z[0])];
  177                         break;
  178                 }
  179                 switch (i & 12) {
  180                  case 0:
  181                  case 12:
  182                         key->xkey[i+0] = cast_sbox5[U_INT8_Ta(t[2])] ^ cast_sbox6[U_INT8_Tb(t[2])] ^
  183                          cast_sbox7[U_INT8_Td(t[1])] ^ cast_sbox8[U_INT8_Tc(t[1])];
  184                         key->xkey[i+1] = cast_sbox5[U_INT8_Tc(t[2])] ^ cast_sbox6[U_INT8_Td(t[2])] ^
  185                          cast_sbox7[U_INT8_Tb(t[1])] ^ cast_sbox8[U_INT8_Ta(t[1])];
  186                         key->xkey[i+2] = cast_sbox5[U_INT8_Ta(t[3])] ^ cast_sbox6[U_INT8_Tb(t[3])] ^
  187                          cast_sbox7[U_INT8_Td(t[0])] ^ cast_sbox8[U_INT8_Tc(t[0])];
  188                         key->xkey[i+3] = cast_sbox5[U_INT8_Tc(t[3])] ^ cast_sbox6[U_INT8_Td(t[3])] ^
  189                          cast_sbox7[U_INT8_Tb(t[0])] ^ cast_sbox8[U_INT8_Ta(t[0])];
  190                         break;
  191                  case 4:
  192                  case 8:
  193                         key->xkey[i+0] = cast_sbox5[U_INT8_Td(t[0])] ^ cast_sbox6[U_INT8_Tc(t[0])] ^
  194                          cast_sbox7[U_INT8_Ta(t[3])] ^ cast_sbox8[U_INT8_Tb(t[3])];
  195                         key->xkey[i+1] = cast_sbox5[U_INT8_Tb(t[0])] ^ cast_sbox6[U_INT8_Ta(t[0])] ^
  196                          cast_sbox7[U_INT8_Tc(t[3])] ^ cast_sbox8[U_INT8_Td(t[3])];
  197                         key->xkey[i+2] = cast_sbox5[U_INT8_Td(t[1])] ^ cast_sbox6[U_INT8_Tc(t[1])] ^
  198                          cast_sbox7[U_INT8_Ta(t[2])] ^ cast_sbox8[U_INT8_Tb(t[2])];
  199                         key->xkey[i+3] = cast_sbox5[U_INT8_Tb(t[1])] ^ cast_sbox6[U_INT8_Ta(t[1])] ^
  200                          cast_sbox7[U_INT8_Tc(t[2])] ^ cast_sbox8[U_INT8_Td(t[2])];
  201                         break;
  202                 }
  203                 switch (i & 12) {
  204                  case 0:
  205                         key->xkey[i+0] ^= cast_sbox5[U_INT8_Tc(z[0])];
  206                         key->xkey[i+1] ^= cast_sbox6[U_INT8_Tc(z[1])];
  207                         key->xkey[i+2] ^= cast_sbox7[U_INT8_Tb(z[2])];
  208                         key->xkey[i+3] ^= cast_sbox8[U_INT8_Ta(z[3])];
  209                         break;
  210                  case 4:
  211                         key->xkey[i+0] ^= cast_sbox5[U_INT8_Ta(x[2])];
  212                         key->xkey[i+1] ^= cast_sbox6[U_INT8_Tb(x[3])];
  213                         key->xkey[i+2] ^= cast_sbox7[U_INT8_Td(x[0])];
  214                         key->xkey[i+3] ^= cast_sbox8[U_INT8_Td(x[1])];
  215                         break;
  216                  case 8:
  217                         key->xkey[i+0] ^= cast_sbox5[U_INT8_Tb(z[2])];
  218                         key->xkey[i+1] ^= cast_sbox6[U_INT8_Ta(z[3])];
  219                         key->xkey[i+2] ^= cast_sbox7[U_INT8_Tc(z[0])];
  220                         key->xkey[i+3] ^= cast_sbox8[U_INT8_Tc(z[1])];
  221                         break;
  222                  case 12:
  223                         key->xkey[i+0] ^= cast_sbox5[U_INT8_Td(x[0])];
  224                         key->xkey[i+1] ^= cast_sbox6[U_INT8_Td(x[1])];
  225                         key->xkey[i+2] ^= cast_sbox7[U_INT8_Ta(x[2])];
  226                         key->xkey[i+3] ^= cast_sbox8[U_INT8_Tb(x[3])];
  227                         break;
  228                 }
  229                 if (i >= 16) {
  230                         key->xkey[i+0] &= 31;
  231                         key->xkey[i+1] &= 31;
  232                         key->xkey[i+2] &= 31;
  233                         key->xkey[i+3] &= 31;
  234                 }
  235         }
  236         /* Wipe clean */
  237         for (i = 0; i < 4; i++) {
  238                 t[i] = x[i] = z[i] = 0;
  239         }
  240 }
  241 
  242 /* Made in Canada */
  243
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FreeBSD/Linux Kernel Cross Reference sys/opencrypto/cast.c

FreeBSD/Linux Kernel Cross Reference
sys/opencrypto/cast.c
