Пример #1
0
static int _tweak_uncrypt(const unsigned char *C, unsigned char *P, unsigned char *T, symmetric_xts *xts)
{
   unsigned long x;
   int err;

   /* tweak encrypt block i */
#ifdef LTC_FAST
   for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {
      *(LTC_FAST_TYPE_PTR_CAST(&P[x])) = *(LTC_FAST_TYPE_PTR_CAST(&C[x])) ^ *(LTC_FAST_TYPE_PTR_CAST(&T[x]));
   }
#else
   for (x = 0; x < 16; x++) {
      P[x] = C[x] ^ T[x];
   }
#endif

   err = cipher_descriptor[xts->cipher].ecb_decrypt(P, P, &xts->key1);

#ifdef LTC_FAST
   for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {
      *(LTC_FAST_TYPE_PTR_CAST(&P[x])) ^= *(LTC_FAST_TYPE_PTR_CAST(&T[x]));
   }
#else
   for (x = 0; x < 16; x++) {
      P[x] = P[x] ^ T[x];
   }
#endif

   /* LFSR the tweak */
   xts_mult_x(T);

   return err;
}
Пример #2
0
/**
  GCM multiply by H
  @param gcm   The GCM state which holds the H value
  @param I     The value to multiply H by
 */
void gcm_mult_h(const gcm_state *gcm, unsigned char *I)
{
   unsigned char T[16];
#ifdef LTC_GCM_TABLES
   int x;
#ifdef LTC_GCM_TABLES_SSE2
   asm("movdqa (%0),%%xmm0"::"r"(&gcm->PC[0][I[0]][0]));
   for (x = 1; x < 16; x++) {
      asm("pxor (%0),%%xmm0"::"r"(&gcm->PC[x][I[x]][0]));
   }
   asm("movdqa %%xmm0,(%0)"::"r"(&T));
#else
   int y;
   XMEMCPY(T, &gcm->PC[0][I[0]][0], 16);
   for (x = 1; x < 16; x++) {
#ifdef LTC_FAST
       for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
           *(LTC_FAST_TYPE_PTR_CAST(T + y)) ^= *(LTC_FAST_TYPE_PTR_CAST(&gcm->PC[x][I[x]][y]));
       }
#else
       for (y = 0; y < 16; y++) {
           T[y] ^= gcm->PC[x][I[x]][y];
       }
#endif /* LTC_FAST */
   }
#endif /* LTC_GCM_TABLES_SSE2 */
#else
   gcm_gf_mult(gcm->H, I, T);
#endif
   XMEMCPY(I, T, 16);
}
Пример #3
0
/**
  CTR encrypt software implementation
  @param pt     Plaintext
  @param ct     [out] Ciphertext
  @param len    Length of plaintext (octets)
  @param ctr    CTR state
  @return CRYPT_OK if successful
*/
static int _ctr_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_CTR *ctr)
{
   int x, err;

   while (len) {
      /* is the pad empty? */
      if (ctr->padlen == ctr->blocklen) {
         /* increment counter */
         if (ctr->mode == CTR_COUNTER_LITTLE_ENDIAN) {
            /* little-endian */
            for (x = 0; x < ctr->ctrlen; x++) {
               ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255;
               if (ctr->ctr[x] != (unsigned char)0) {
                  break;
               }
            }
         } else {
            /* big-endian */
            for (x = ctr->blocklen-1; x >= ctr->ctrlen; x--) {
               ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255;
               if (ctr->ctr[x] != (unsigned char)0) {
                  break;
               }
            }
         }

         /* encrypt it */
         if ((err = cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key)) != CRYPT_OK) {
            return err;
         }
         ctr->padlen = 0;
      }
#ifdef LTC_FAST
      if ((ctr->padlen == 0) && (len >= (unsigned long)ctr->blocklen)) {
         for (x = 0; x < ctr->blocklen; x += sizeof(LTC_FAST_TYPE)) {
            *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)ct + x)) = *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)pt + x)) ^
                                                           *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)ctr->pad + x));
         }
       pt         += ctr->blocklen;
       ct         += ctr->blocklen;
       len        -= ctr->blocklen;
       ctr->padlen = ctr->blocklen;
       continue;
      }
#endif
      *ct++ = *pt++ ^ ctr->pad[ctr->padlen++];
      --len;
   }
   return CRYPT_OK;
}
Пример #4
0
/** Process data through f9-MAC
  @param f9       The f9-MAC state
  @param in       Input data to process
  @param inlen    Length of input in octets
  Return CRYPT_OK on success
*/
int f9_process(f9_state *f9, const unsigned char *in, unsigned long inlen)
{
   int err, x;

   LTC_ARGCHK(f9 != NULL);
   LTC_ARGCHK(in   != NULL);

   /* check structure */
   if ((err = cipher_is_valid(f9->cipher)) != CRYPT_OK) {
      return err;
   }

   if ((f9->blocksize > cipher_descriptor[f9->cipher].block_length) || (f9->blocksize < 0) ||
       (f9->buflen > f9->blocksize) || (f9->buflen < 0)) {
      return CRYPT_INVALID_ARG;
   }

#ifdef LTC_FAST
   if (f9->buflen == 0) {
       while (inlen >= (unsigned long)f9->blocksize) {
           for (x = 0; x < f9->blocksize; x += sizeof(LTC_FAST_TYPE)) {
              *(LTC_FAST_TYPE_PTR_CAST(&(f9->IV[x]))) ^= *(LTC_FAST_TYPE_PTR_CAST(&(in[x])));
           }
           cipher_descriptor[f9->cipher].ecb_encrypt(f9->IV, f9->IV, &f9->key);
           for (x = 0; x < f9->blocksize; x += sizeof(LTC_FAST_TYPE)) {
              *(LTC_FAST_TYPE_PTR_CAST(&(f9->ACC[x]))) ^= *(LTC_FAST_TYPE_PTR_CAST(&(f9->IV[x])));
           }
           in    += f9->blocksize;
           inlen -= f9->blocksize;
       }
   }
#endif

   while (inlen) {
      if (f9->buflen == f9->blocksize) {
         cipher_descriptor[f9->cipher].ecb_encrypt(f9->IV, f9->IV, &f9->key);
         for (x = 0; x < f9->blocksize; x++) {
            f9->ACC[x] ^= f9->IV[x];
         }
         f9->buflen = 0;
      }
      f9->IV[f9->buflen++] ^= *in++;
      --inlen;
   }
   return CRYPT_OK;
}
Пример #5
0
/** Process data through XCBC-MAC
  @param xcbc     The XCBC-MAC state
  @param in       Input data to process
  @param inlen    Length of input in octets
  Return CRYPT_OK on success
*/
int xcbc_process(xcbc_state *xcbc, const unsigned char *in, unsigned long inlen)
{
   int err;
#ifdef LTC_FAST
   int x;
#endif

   LTC_ARGCHK(xcbc != NULL);
   LTC_ARGCHK(in   != NULL);

   /* check structure */
   if ((err = cipher_is_valid(xcbc->cipher)) != CRYPT_OK) {
      return err;
   }

   if ((xcbc->blocksize > cipher_descriptor[xcbc->cipher].block_length) || (xcbc->blocksize < 0) ||
       (xcbc->buflen > xcbc->blocksize) || (xcbc->buflen < 0)) {
      return CRYPT_INVALID_ARG;
   }

#ifdef LTC_FAST
   if (xcbc->buflen == 0) {
       while (inlen > (unsigned long)xcbc->blocksize) {
           for (x = 0; x < xcbc->blocksize; x += sizeof(LTC_FAST_TYPE)) {
              *(LTC_FAST_TYPE_PTR_CAST(&(xcbc->IV[x]))) ^= *(LTC_FAST_TYPE_PTR_CAST(&(in[x])));
           }
           cipher_descriptor[xcbc->cipher].ecb_encrypt(xcbc->IV, xcbc->IV, &xcbc->key);
           in    += xcbc->blocksize;
           inlen -= xcbc->blocksize;
       }
   }
#endif

   while (inlen) {
      if (xcbc->buflen == xcbc->blocksize) {
         cipher_descriptor[xcbc->cipher].ecb_encrypt(xcbc->IV, xcbc->IV, &xcbc->key);
         xcbc->buflen = 0;
      }
      xcbc->IV[xcbc->buflen++] ^= *in++;
      --inlen;
   }
   return CRYPT_OK;
}
Пример #6
0
/**
  Add AAD to the GCM state
  @param gcm       The GCM state
  @param adata     The additional authentication data to add to the GCM state
  @param adatalen  The length of the AAD data.
  @return CRYPT_OK on success
 */
int gcm_add_aad(gcm_state *gcm,
               const unsigned char *adata,  unsigned long adatalen)
{
   unsigned long x;
   int           err;
#ifdef LTC_FAST
   unsigned long y;
#endif

   LTC_ARGCHK(gcm    != NULL);
   if (adatalen > 0) {
      LTC_ARGCHK(adata  != NULL);
   }

   if (gcm->buflen > 16 || gcm->buflen < 0) {
      return CRYPT_INVALID_ARG;
   }

   if ((err = cipher_is_valid(gcm->cipher)) != CRYPT_OK) {
      return err;
   }

   /* in IV mode? */
   if (gcm->mode == LTC_GCM_MODE_IV) {
      /* IV length must be > 0 */
      if (gcm->buflen == 0 && gcm->totlen == 0) return CRYPT_ERROR;
      /* let's process the IV */
      if (gcm->ivmode || gcm->buflen != 12) {
         for (x = 0; x < (unsigned long)gcm->buflen; x++) {
             gcm->X[x] ^= gcm->buf[x];
         }
         if (gcm->buflen) {
            gcm->totlen += gcm->buflen * CONST64(8);
            gcm_mult_h(gcm, gcm->X);
         }

         /* mix in the length */
         zeromem(gcm->buf, 8);
         STORE64H(gcm->totlen, gcm->buf+8);
         for (x = 0; x < 16; x++) {
             gcm->X[x] ^= gcm->buf[x];
         }
         gcm_mult_h(gcm, gcm->X);

         /* copy counter out */
         XMEMCPY(gcm->Y, gcm->X, 16);
         zeromem(gcm->X, 16);
      } else {
         XMEMCPY(gcm->Y, gcm->buf, 12);
         gcm->Y[12] = 0;
         gcm->Y[13] = 0;
         gcm->Y[14] = 0;
         gcm->Y[15] = 1;
      }
      XMEMCPY(gcm->Y_0, gcm->Y, 16);
      zeromem(gcm->buf, 16);
      gcm->buflen = 0;
      gcm->totlen = 0;
      gcm->mode   = LTC_GCM_MODE_AAD;
   }

   if (gcm->mode != LTC_GCM_MODE_AAD || gcm->buflen >= 16) {
      return CRYPT_INVALID_ARG;
   }

   x = 0;
#ifdef LTC_FAST
   if (gcm->buflen == 0) {
      for (x = 0; x < (adatalen & ~15); x += 16) {
          for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
              *(LTC_FAST_TYPE_PTR_CAST(&gcm->X[y])) ^= *(LTC_FAST_TYPE_PTR_CAST(&adata[x + y]));
          }
          gcm_mult_h(gcm, gcm->X);
          gcm->totlen += 128;
      }
      adata += x;
   }
#endif


   /* start adding AAD data to the state */
   for (; x < adatalen; x++) {
      gcm->X[gcm->buflen++] ^= *adata++;

      if (gcm->buflen == 16) {
         /* GF mult it */
         gcm_mult_h(gcm, gcm->X);
         gcm->buflen = 0;
         gcm->totlen += 128;
      }
   }

   return CRYPT_OK;
}
Пример #7
0
/**
  CBC decrypt
  @param ct     Ciphertext
  @param pt     [out] Plaintext
  @param len    The number of bytes to process (must be multiple of block length)
  @param cbc    CBC state
  @return CRYPT_OK if successful
*/
int cbc_decrypt(const unsigned char *ct, unsigned char *pt, unsigned long len, symmetric_CBC *cbc)
{
   int x, err;
   unsigned char tmp[16];
#ifdef LTC_FAST
   LTC_FAST_TYPE tmpy;
#else
   unsigned char tmpy;
#endif

   LTC_ARGCHK(pt  != NULL);
   LTC_ARGCHK(ct  != NULL);
   LTC_ARGCHK(cbc != NULL);

   if ((err = cipher_is_valid(cbc->cipher)) != CRYPT_OK) {
       return err;
   }

   /* is blocklen valid? */
   if (cbc->blocklen < 1 || cbc->blocklen > (int)sizeof(cbc->IV) || cbc->blocklen > (int)sizeof(tmp)) {
      return CRYPT_INVALID_ARG;
   }

   if (len % cbc->blocklen) {
      return CRYPT_INVALID_ARG;
   }
#ifdef LTC_FAST
   if (cbc->blocklen % sizeof(LTC_FAST_TYPE)) {
      return CRYPT_INVALID_ARG;
   }
#endif

   if (cipher_descriptor[cbc->cipher].accel_cbc_decrypt != NULL) {
      return cipher_descriptor[cbc->cipher].accel_cbc_decrypt(ct, pt, len / cbc->blocklen, cbc->IV, &cbc->key);
   } else {
      while (len) {
         /* decrypt */
         if ((err = cipher_descriptor[cbc->cipher].ecb_decrypt(ct, tmp, &cbc->key)) != CRYPT_OK) {
            return err;
         }

         /* xor IV against plaintext */
         #if defined(LTC_FAST)
         for (x = 0; x < cbc->blocklen; x += sizeof(LTC_FAST_TYPE)) {
            tmpy = *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)cbc->IV + x)) ^ *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)tmp + x));
            *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)cbc->IV + x)) = *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)ct + x));
            *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)pt + x)) = tmpy;
         }
    #else
         for (x = 0; x < cbc->blocklen; x++) {
            tmpy       = tmp[x] ^ cbc->IV[x];
            cbc->IV[x] = ct[x];
            pt[x]      = tmpy;
         }
    #endif

         ct  += cbc->blocklen;
         pt  += cbc->blocklen;
         len -= cbc->blocklen;
      }
   }
   return CRYPT_OK;
}
Пример #8
0
/**
  Add IV data to the GCM state
  @param gcm    The GCM state
  @param IV     The initial value data to add
  @param IVlen  The length of the IV
  @return CRYPT_OK on success
 */
int gcm_add_iv(gcm_state *gcm,
               const unsigned char *IV,     unsigned long IVlen)
{
   unsigned long x, y;
   int           err;

   LTC_ARGCHK(gcm != NULL);
   if (IVlen > 0) {
      LTC_ARGCHK(IV  != NULL);
   }

   /* must be in IV mode */
   if (gcm->mode != LTC_GCM_MODE_IV) {
      return CRYPT_INVALID_ARG;
   }

   if (gcm->buflen >= 16 || gcm->buflen < 0) {
      return CRYPT_INVALID_ARG;
   }

   if ((err = cipher_is_valid(gcm->cipher)) != CRYPT_OK) {
      return err;
   }


   /* trip the ivmode flag */
   if (IVlen + gcm->buflen > 12) {
      gcm->ivmode |= 1;
   }

   x = 0;
#ifdef LTC_FAST
   if (gcm->buflen == 0) {
      for (x = 0; x < (IVlen & ~15); x += 16) {
          for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
              *(LTC_FAST_TYPE_PTR_CAST(&gcm->X[y])) ^= *(LTC_FAST_TYPE_PTR_CAST(&IV[x + y]));
          }
          gcm_mult_h(gcm, gcm->X);
          gcm->totlen += 128;
      }
      IV += x;
   }
#endif

   /* start adding IV data to the state */
   for (; x < IVlen; x++) {
       gcm->buf[gcm->buflen++] = *IV++;

      if (gcm->buflen == 16) {
         /* GF mult it */
         for (y = 0; y < 16; y++) {
             gcm->X[y] ^= gcm->buf[y];
         }
         gcm_mult_h(gcm, gcm->X);
         gcm->buflen = 0;
         gcm->totlen += 128;
      }
   }

   return CRYPT_OK;
}
Пример #9
0
/* Test store/load macros with offsets */
int store_test(void)
{
  unsigned char buf[256];
  int y;
  ulong32 L, L1;
  ulong64 LL, LL1;
#ifdef LTC_FAST
  int x, z;
#endif

  for (y = 0; y < 4; y++) {
      L  = 0x12345678UL;
      L1 = 0;
      STORE32L(L, buf + y);
      LOAD32L(L1, buf + y);
      if (L1 != L) {
         fprintf(stderr, "\n32L failed at offset %d\n", y);
         return 1;
      }
      STORE32H(L, buf + y);
      LOAD32H(L1, buf + y);
      if (L1 != L) {
         fprintf(stderr, "\n32H failed at offset %d\n", y);
         return 1;
      }
  }

  for (y = 0; y < 8; y++) {
      LL = CONST64 (0x01020304050607);
      LL1 = 0;
      STORE64L(LL, buf + y);
      LOAD64L(LL1, buf + y);
      if (LL1 != LL) {
         fprintf(stderr, "\n64L failed at offset %d\n", y);
         return 1;
      }
      STORE64H(LL, buf + y);
      LOAD64H(LL1, buf + y);
      if (LL1 != LL) {
         fprintf(stderr, "\n64H failed at offset %d\n", y);
         return 1;
      }
  }

/* test LTC_FAST */
#ifdef LTC_FAST
  y = 16;

  for (z = 0; z < y; z++) {
     /* fill y bytes with random */
     yarrow_read(buf+z,   y, &yarrow_prng);
     yarrow_read(buf+z+y, y, &yarrow_prng);

     /* now XOR it byte for byte */
     for (x = 0; x < y; x++) {
         buf[2*y+z+x] = buf[z+x] ^ buf[z+y+x];
     }

     /* now XOR it word for word */
     for (x = 0; x < y; x += sizeof(LTC_FAST_TYPE)) {
        *(LTC_FAST_TYPE_PTR_CAST(&buf[3*y+z+x])) = *(LTC_FAST_TYPE_PTR_CAST(&buf[z+x])) ^ *(LTC_FAST_TYPE_PTR_CAST(&buf[z+y+x]));
     }

     if (memcmp(&buf[2*y+z], &buf[3*y+z], y)) {
        fprintf(stderr, "\nLTC_FAST failed at offset %d\n", z);
        return 1;
     }
  }
#endif
  return 0;
}
Пример #10
0
/**
  Process data in a PMAC stream
  @param pmac     The PMAC state
  @param in       The data to send through PMAC
  @param inlen    The length of the data to send through PMAC
  @return CRYPT_OK if successful
*/
int pmac_process(pmac_state *pmac, const unsigned char *in, unsigned long inlen)
{
   int err, n;
   unsigned long x;
   unsigned char Z[MAXBLOCKSIZE];

   LTC_ARGCHK(pmac != NULL);
   LTC_ARGCHK(in   != NULL);
   if ((err = cipher_is_valid(pmac->cipher_idx)) != CRYPT_OK) {
      return err;
   }

   if ((pmac->buflen > (int)sizeof(pmac->block)) || (pmac->buflen < 0) ||
       (pmac->block_len > (int)sizeof(pmac->block)) || (pmac->buflen > pmac->block_len)) {
      return CRYPT_INVALID_ARG;
   }

#ifdef LTC_FAST
   if (pmac->buflen == 0 && inlen > 16) {
      unsigned long y;
      for (x = 0; x < (inlen - 16); x += 16) {
          pmac_shift_xor(pmac);
          for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
              *(LTC_FAST_TYPE_PTR_CAST(&Z[y])) = *(LTC_FAST_TYPE_PTR_CAST(&in[y])) ^ *(LTC_FAST_TYPE_PTR_CAST(&pmac->Li[y]));
          }
          if ((err = cipher_descriptor[pmac->cipher_idx].ecb_encrypt(Z, Z, &pmac->key)) != CRYPT_OK) {
             return err;
          }
          for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
              *(LTC_FAST_TYPE_PTR_CAST(&pmac->checksum[y])) ^= *(LTC_FAST_TYPE_PTR_CAST(&Z[y]));
          }
          in += 16;
      }
      inlen -= x;
   }
#endif

   while (inlen != 0) {
       /* ok if the block is full we xor in prev, encrypt and replace prev */
       if (pmac->buflen == pmac->block_len) {
          pmac_shift_xor(pmac);
          for (x = 0; x < (unsigned long)pmac->block_len; x++) {
               Z[x] = pmac->Li[x] ^ pmac->block[x];
          }
          if ((err = cipher_descriptor[pmac->cipher_idx].ecb_encrypt(Z, Z, &pmac->key)) != CRYPT_OK) {
             return err;
           }
          for (x = 0; x < (unsigned long)pmac->block_len; x++) {
              pmac->checksum[x] ^= Z[x];
          }
          pmac->buflen = 0;
       }

       /* add bytes */
       n = MIN(inlen, (unsigned long)(pmac->block_len - pmac->buflen));
       XMEMCPY(pmac->block + pmac->buflen, in, n);
       pmac->buflen  += n;
       inlen         -= n;
       in            += n;
   }

#ifdef LTC_CLEAN_STACK
   zeromem(Z, sizeof(Z));
#endif

   return CRYPT_OK;
}
Пример #11
0
/**
  CBC encrypt
  @param pt     Plaintext
  @param ct     [out] Ciphertext
  @param len    The number of bytes to process (must be multiple of block length)
  @param cbc    CBC state
  @return CRYPT_OK if successful
*/
int cbc_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_CBC *cbc)
{
   int x, err;

   LTC_ARGCHK(pt != NULL);
   LTC_ARGCHK(ct != NULL);
   LTC_ARGCHK(cbc != NULL);

   if ((err = cipher_is_valid(cbc->cipher)) != CRYPT_OK) {
       return err;
   }

   /* is blocklen valid? */
   if (cbc->blocklen < 1 || cbc->blocklen > (int)sizeof(cbc->IV)) {
      return CRYPT_INVALID_ARG;
   }

   if (len % cbc->blocklen) {
      return CRYPT_INVALID_ARG;
   }
#ifdef LTC_FAST
   if (cbc->blocklen % sizeof(LTC_FAST_TYPE)) {
      return CRYPT_INVALID_ARG;
   }
#endif

   if (cipher_descriptor[cbc->cipher].accel_cbc_encrypt != NULL) {
      return cipher_descriptor[cbc->cipher].accel_cbc_encrypt(pt, ct, len / cbc->blocklen, cbc->IV, &cbc->key);
   } else {
      while (len) {
         /* xor IV against plaintext */
         #if defined(LTC_FAST)
         for (x = 0; x < cbc->blocklen; x += sizeof(LTC_FAST_TYPE)) {
            *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)cbc->IV + x)) ^= *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)pt + x));
         }
    #else
         for (x = 0; x < cbc->blocklen; x++) {
            cbc->IV[x] ^= pt[x];
         }
    #endif

         /* encrypt */
         if ((err = cipher_descriptor[cbc->cipher].ecb_encrypt(cbc->IV, ct, &cbc->key)) != CRYPT_OK) {
            return err;
         }

         /* store IV [ciphertext] for a future block */
         #if defined(LTC_FAST)
         for (x = 0; x < cbc->blocklen; x += sizeof(LTC_FAST_TYPE)) {
            *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)cbc->IV + x)) = *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)ct + x));
         }
    #else
         for (x = 0; x < cbc->blocklen; x++) {
            cbc->IV[x] = ct[x];
         }
    #endif

         ct  += cbc->blocklen;
         pt  += cbc->blocklen;
         len -= cbc->blocklen;
      }
   }
   return CRYPT_OK;
}