MainClass.java Source code

Introduction

Here is the source code for MainClass.java

Source

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.Security;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;

public class MainClass {
    static Cipher m_encrypter;

    static Cipher m_decrypter;

    public static void main(String args[]) throws Exception {
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());

        SecretKey key = KeyGenerator.getInstance("DES").generateKey();

        // for CBC; must be 8 bytes
        byte[] initVector = new byte[] { 0x10, 0x10, 0x01, 0x04, 0x01, 0x01, 0x01, 0x02 };

        AlgorithmParameterSpec algParamSpec = new IvParameterSpec(initVector);
        Cipher m_encrypter = Cipher.getInstance("DES/CBC/PKCS5Padding");
        Cipher m_decrypter = Cipher.getInstance("DES/CBC/PKCS5Padding");

        m_encrypter.init(Cipher.ENCRYPT_MODE, key, algParamSpec);
        m_decrypter.init(Cipher.DECRYPT_MODE, key, algParamSpec);

        FileInputStream fis = new FileInputStream("cipherTest.in");
        FileOutputStream fos = new FileOutputStream("cipherTest.out");
        int dataInputSize = fis.available();

        byte[] inputBytes = new byte[dataInputSize];
        fis.read(inputBytes);
        write(inputBytes, fos);
        fos.flush();
        fis.close();
        fos.close();

        String inputFileAsString = new String(inputBytes);
        System.out.println("INPUT FILE CONTENTS\n" + inputFileAsString + "\n");

        System.out.println("File encrypted and saved to disk\n");

        fis = new FileInputStream("cipherTest.out");

        byte[] decrypted = new byte[dataInputSize];
        read(decrypted, fis);

        fis.close();
        String decryptedAsString = new String(decrypted);

        System.out.println("DECRYPTED FILE:\n" + decryptedAsString + "\n");

    }

    public static void write(byte[] bytes, OutputStream out) throws Exception {
        CipherOutputStream cos = new CipherOutputStream(out, m_encrypter);
        cos.write(bytes, 0, bytes.length);
        cos.close();
    }

    public static void read(byte[] bytes, InputStream in) throws Exception {
        CipherInputStream cis = new CipherInputStream(in, m_decrypter);
        int pos = 0, intValue;

        while ((intValue = cis.read()) != -1) {
            bytes[pos] = (byte) intValue;
            pos++;
        }
    }

}