com.l2jfree.tools.math.ScrambledKeyPair.java Source code

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Here is the source code for com.l2jfree.tools.math.ScrambledKeyPair.java

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/*
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package com.l2jfree.tools.math;

import java.math.BigInteger;
import java.security.KeyPair;
import java.security.interfaces.RSAPublicKey;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class ScrambledKeyPair {
    private final static Log _log = LogFactory.getLog(ScrambledKeyPair.class);

    private KeyPair pair;
    private byte[] scrambledModulus;

    public ScrambledKeyPair(KeyPair Pair) {
        pair = Pair;
        scrambledModulus = scrambleModulus(((RSAPublicKey) pair.getPublic()).getModulus());
    }

    private byte[] scrambleModulus(BigInteger modulus) {
        byte[] retScrambledModulus = modulus.toByteArray();

        if (retScrambledModulus.length == 0x81 && retScrambledModulus[0] == 0x00) {
            byte[] temp = new byte[0x80];
            System.arraycopy(retScrambledModulus, 1, temp, 0, 0x80);
            retScrambledModulus = temp;
        }
        // step 1 : 0x4d-0x50 <-> 0x00-0x04
        for (int i = 0; i < 4; i++) {
            byte temp = retScrambledModulus[0x00 + i];
            retScrambledModulus[0x00 + i] = retScrambledModulus[0x4d + i];
            retScrambledModulus[0x4d + i] = temp;
        }
        // step 2 : xor first 0x40 bytes with last 0x40 bytes
        for (int i = 0; i < 0x40; i++) {
            retScrambledModulus[i] = (byte) (retScrambledModulus[i] ^ retScrambledModulus[0x40 + i]);
        }
        // step 3 : xor bytes 0x0d-0x10 with bytes 0x34-0x38
        for (int i = 0; i < 4; i++) {
            retScrambledModulus[0x0d + i] = (byte) (retScrambledModulus[0x0d + i] ^ retScrambledModulus[0x34 + i]);
        }
        // step 4 : xor last 0x40 bytes with first 0x40 bytes
        for (int i = 0; i < 0x40; i++) {
            retScrambledModulus[0x40 + i] = (byte) (retScrambledModulus[0x40 + i] ^ retScrambledModulus[i]);
        }
        if (_log.isDebugEnabled())
            _log.debug("Modulus was scrambled");

        return retScrambledModulus;
    }

    public KeyPair getPair() {
        return pair;
    }

    public void setPair(KeyPair pair) {
        this.pair = pair;
    }

    public byte[] getScrambledModulus() {
        return scrambledModulus;
    }

    public void setScrambledModulus(byte[] scrambledModulus) {
        this.scrambledModulus = scrambledModulus;
    }
}