private void init() throws IOException {
if (xts != null) {
return;
}
this.size = base.size() - HEADER_LENGTH;
boolean newFile = size < 0;
byte[] salt;
if (newFile) {
byte[] header = Arrays.copyOf(HEADER, BLOCK_SIZE);
salt = MathUtils.secureRandomBytes(SALT_LENGTH);
System.arraycopy(salt, 0, header, SALT_POS, salt.length);
DataUtils.writeFully(base, 0, ByteBuffer.wrap(header));
size = 0;
} else {
salt = new byte[SALT_LENGTH];
DataUtils.readFully(base, SALT_POS, ByteBuffer.wrap(salt));
if ((size & BLOCK_SIZE_MASK) != 0) {
size -= BLOCK_SIZE;
}
}
AES cipher = new AES();
cipher.setKey(SHA256.getPBKDF2(encryptionKey, salt, HASH_ITERATIONS, 16));
encryptionKey = null;
xts = new XTS(cipher);
}