tftweakapi.c

   1 #include <string.h>
   2 #include "tfdef.h"
   3 #include "tfcore.h"
   4
   5 void tf_tweak_set(void *key, const void *tweak)
   6 {
   7         TF_UNIT_TYPE *ukey = key;
   8         TF_UNIT_TYPE *twe = ukey+TF_TWEAK_WORD1;
   9         TF_UNIT_TYPE c = THREEFISH_CONST;
  10         size_t x;
  11
  12         for (x = 0; x < TF_NR_BLOCK_UNITS; x++) c ^= ukey[x];
  13         ukey[x] = c;
  14
  15         if (!tweak) {
  16                 memset(twe, 0, (TF_NR_TWEAK_UNITS+1)*TF_SIZE_UNIT);
  17                 return;
  18         }
  19
  20         memcpy(twe, tweak, TF_NR_TWEAK_UNITS*TF_SIZE_UNIT);
  21         data_to_words(twe, TF_NR_TWEAK_UNITS*TF_SIZE_UNIT);
  22         ukey[TF_TWEAK_WORD3] = ukey[TF_TWEAK_WORD1] ^ ukey[TF_TWEAK_WORD2];
  23 }