lib/cbc.c

   1 #include <stdlib.h>
   2 #include <string.h>
   3
   4 #include "cbc.h"
   5 #include "rijndael.h"
   6
   7 rijndaelcbc *rijndaelcbc_init(unsigned char *key, int keybits, unsigned char *iv, int decrypt) {
   8   rijndaelcbc *ret = (rijndaelcbc *)malloc(sizeof(rijndaelcbc) + RKLENGTH(keybits) * sizeof(unsigned long));
   9   if(!ret)
  10     return NULL;
  11
  12   memcpy(ret->prevblock, iv, 16);
  13
  14   if(decrypt) {
  15     ret->nrounds = rijndaelSetupDecrypt(ret->rk, key, keybits);
  16   } else {
  17     ret->nrounds = rijndaelSetupEncrypt(ret->rk, key, keybits);
  18   }
  19
  20   return ret;
  21 }
  22
  23 void rijndaelcbc_free(rijndaelcbc *c) {
  24   free(c);
  25 }
  26
  27 unsigned char *rijndaelcbc_encrypt(rijndaelcbc *c, unsigned char *ptblock) {
  28   int i;
  29   unsigned char *p = c->prevblock, *p2 = c->scratch;
  30   for(i=0;i<16;i++)
  31     *p2++ = *p++ ^ *ptblock++;
  32
  33   rijndaelEncrypt(c->rk, c->nrounds, c->scratch, c->prevblock);
  34   return c->prevblock;
  35 }
  36
  37 unsigned char *rijndaelcbc_decrypt(rijndaelcbc *c, unsigned char *ctblock) {
  38   int i;
  39   unsigned char *p = c->prevblock, *p2 = c->scratch;
  40
  41   rijndaelDecrypt(c->rk, c->nrounds, ctblock, c->scratch);
  42
  43   for(i=0;i<16;i++)
  44     *p2++^=*p++;
  45
  46   memcpy(c->prevblock, ctblock, 16);
  47   return c->scratch;
  48 }
  49