void Blowfish_Encrypt_Buffer_CBC(BLOWFISH_CTX *ctx, void *buffer_,
                                 size_t length, void *iv_) {
  uint64_t *buffer = buffer_;
  uint64_t *iv = iv_;
  uint64_t lastcb = *iv;
  size_t i;

  for (i = 0; i < length / 8; ++i) {
    buffer[i] ^= lastcb;
    Blowfish_Encrypt(ctx, (uint32_t *)(buffer+i), (uint32_t *)(buffer+i)+1);
    lastcb = buffer[i];
  }
  *iv = lastcb;
}