tfctr.c

   1 #include <string.h>
   2 #include "tfdef.h"
   3
   4 void tf_ctr_crypt(const void *key, void *ctr, void *out, const void *in, size_t sz)
   5 {
   6         const TF_BYTE_TYPE *uin = in;
   7         TF_BYTE_TYPE *uout = out;
   8         TF_UNIT_TYPE x[TF_NR_BLOCK_UNITS], y[TF_NR_BLOCK_UNITS];
   9         TF_UNIT_TYPE *uctr = ctr;
  10         const TF_UNIT_TYPE *ukey = key;
  11         size_t sl = sz, i;
  12
  13         if (sl >= TF_BLOCK_SIZE) {
  14                 do {
  15                         memcpy(x, uin, TF_BLOCK_SIZE);
  16                         uin += TF_BLOCK_SIZE;
  17                         data_to_words(x, TF_BLOCK_SIZE);
  18
  19                         ctr_inc(uctr, TF_NR_BLOCK_UNITS);
  20                         tf_encrypt_rawblk(y, uctr, ukey);
  21                         for (i = 0; i < TF_NR_BLOCK_UNITS; i++) y[i] ^= x[i];
  22
  23                         data_to_words(y, TF_BLOCK_SIZE);
  24                         memcpy(uout, y, TF_BLOCK_SIZE);
  25                         uout += TF_BLOCK_SIZE;
  26                 } while ((sl -= TF_BLOCK_SIZE) >= TF_BLOCK_SIZE);
  27         }
  28
  29         if (sl) {
  30                 memset(x, 0, TF_BLOCK_SIZE);
  31                 memcpy(x, uin, sl);
  32                 data_to_words(x, TF_BLOCK_SIZE);
  33
  34                 ctr_inc(uctr, TF_NR_BLOCK_UNITS);
  35                 tf_encrypt_rawblk(y, uctr, ukey);
  36                 for (i = 0; i < TF_NR_BLOCK_UNITS; i++) y[i] ^= x[i];
  37
  38                 data_to_words(y, TF_BLOCK_SIZE);
  39                 memcpy(uout, y, sl);
  40         }
  41
  42         memset(x, 0, TF_BLOCK_SIZE);
  43         memset(y, 0, TF_BLOCK_SIZE);
  44 }