package code.kalter.longflight.crypto;

import java.io.IOException;
import java.io.InputStream;

/**
 * Шифровальный входной поток (обёртка для InputStream). Дешифровка:
 * xor -> xchgb
 *
 * @author KalterFive
 */
public class CIStream extends InputStream {

    private final InputStream istream;
    private final Random random;

    // key - ключ для ГПСЧ
    public CIStream(InputStream istream, int key) {
        this.istream = istream;
        this.random = new Random(key);
    }

    public int read() throws IOException {
        int b = istream.read();
        b ^= random.random(0xFF);
        b = (b << 4) | (b >> 4);
        return b;
    }

    public int available() throws IOException {
        return istream.available();
    }

    public void close() throws IOException {
        istream.close();
    }
}