IOUtils.readFully(in, iv);
decryptor.setIv(iv);
// All encrypted blocks will have a nonzero IV length. If we see an IV
// length of zero, this means the encoding context had 0 bytes of
// plaintext to encode.
decryptor.reset();
in = decryptor.createDecryptionStream(in);
}
onDiskSizeWithoutHeader -= Bytes.SIZEOF_BYTE + ivLength;
}