/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.security;
import org.h2.util.Bits;
/**
* A pseudo-encryption algorithm that makes the data appear to be
* encrypted. This algorithm is cryptographically extremely weak, and should
* only be used to hide data from reading the plain text using a text editor.
*/
public class Fog implements BlockCipher {
private int key;
@Override
public void encrypt(byte[] bytes, int off, int len) {
for (int i = off; i < off + len; i += 16) {
encryptBlock(bytes, bytes, i);
}
}
@Override
public void decrypt(byte[] bytes, int off, int len) {
for (int i = off; i < off + len; i += 16) {
decryptBlock(bytes, bytes, i);
}
}
private void encryptBlock(byte[] in, byte[] out, int off) {
int x0 = Bits.readInt(in, off);
int x1 = Bits.readInt(in, off + 4);
int x2 = Bits.readInt(in, off + 8);
int x3 = Bits.readInt(in, off + 12);
int k = key;
x0 = Integer.rotateLeft(x0 ^ k, x1);
x2 = Integer.rotateLeft(x2 ^ k, x1);
x1 = Integer.rotateLeft(x1 ^ k, x0);
x3 = Integer.rotateLeft(x3 ^ k, x0);
Bits.writeInt(out, off, x0);
Bits.writeInt(out, off + 4, x1);
Bits.writeInt(out, off + 8, x2);
Bits.writeInt(out, off + 12, x3);
}
private void decryptBlock(byte[] in, byte[] out, int off) {
int x0 = Bits.readInt(in, off);
int x1 = Bits.readInt(in, off + 4);
int x2 = Bits.readInt(in, off + 8);
int x3 = Bits.readInt(in, off + 12);
int k = key;
x1 = Integer.rotateRight(x1, x0) ^ k;
x3 = Integer.rotateRight(x3, x0) ^ k;
x0 = Integer.rotateRight(x0, x1) ^ k;
x2 = Integer.rotateRight(x2, x1) ^ k;
Bits.writeInt(out, off, x0);
Bits.writeInt(out, off + 4, x1);
Bits.writeInt(out, off + 8, x2);
Bits.writeInt(out, off + 12, x3);
}
@Override
public int getKeyLength() {
return 16;
}
@Override
public void setKey(byte[] key) {
this.key = (int) Bits.readLong(key, 0);
}
}