/**
* Decrypt one block of data. The encrypted data is taken from <code>dest[i..i+7]</code> and
* plaintext is written to <code>source[j..j+7]</code>.
*/
public void decrypt(byte[] source, int i, byte[] dest, int j) {
long block = makeLong(source, i, 8);
block = pickBits(block, IP);
block = subDecrypt(block);
block = pickBits(block, FP);
writeBytes(block, dest, j, 8);
}
/** Return the key-bits for this key as an array of 8 bytes. */
public byte[] getKey() {
byte[] a = new byte[8];
writeBytes(key, a, 0, 8);
return a;
}