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/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2023 Apryse Group NV
    Authors: Apryse Software.

    This program is offered under a commercial and under the AGPL license.
    For commercial licensing, contact us at https://itextpdf.com/sales.  For AGPL licensing, see below.

    AGPL licensing:
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero 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 Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see .
 */
package com.itextpdf.kernel.crypto;


public class ARCFOUREncryption {

    
    private byte[] state = new byte[256];
    private int x;
    private int y;

    /**
     * Creates a new instance of ARCFOUREncryption
     */
    public ARCFOUREncryption() {
    }

    public void prepareARCFOURKey(byte[] key) {
        prepareARCFOURKey(key, 0, key.length);
    }

    public void prepareARCFOURKey(byte[] key, int off, int len) {
        int index1 = 0;
        int index2 = 0;
        for (int k = 0; k < 256; ++k) {
            state[k] = (byte) k;
        }
        x = 0;
        y = 0;
        byte tmp;
        for (int k = 0; k < 256; ++k) {
            index2 = (key[index1 + off] + state[k] + index2) & 255;
            tmp = state[k];
            state[k] = state[index2];
            state[index2] = tmp;
            index1 = (index1 + 1) % len;
        }
    }

    public void encryptARCFOUR(byte[] dataIn, int off, int len, byte[] dataOut, int offOut) {
        int length = len + off;
        byte tmp;
        for (int k = off; k < length; ++k) {
            x = (x + 1) & 255;
            y = (state[x] + y) & 255;
            tmp = state[x];
            state[x] = state[y];
            state[y] = tmp;
            dataOut[k - off + offOut] = (byte) (dataIn[k] ^ state[(state[x] + state[y]) & 255]);
        }
    }

    public void encryptARCFOUR(byte[] data, int off, int len) {
        encryptARCFOUR(data, off, len, data, off);
    }

    public void encryptARCFOUR(byte[] dataIn, byte[] dataOut) {
        encryptARCFOUR(dataIn, 0, dataIn.length, dataOut, 0);
    }

    public void encryptARCFOUR(byte[] data) {
        encryptARCFOUR(data, 0, data.length, data, 0);
    }
}