Simplest way to encrypt a text file in java

Question

For my School project I had to show that I can utilize file handling within a program. For this I made a very simple login process that you can create an account on that wri

Answer 1

public class CryptoUtils {

    public static void encrypt(String key, File inputFile, File outputFile)
            throws CryptoException {
        doCrypto(Cipher.ENCRYPT_MODE, key, inputFile, outputFile);
    }

    public static void decrypt(String key, File inputFile, File outputFile)
            throws CryptoException {
        doCrypto(Cipher.DECRYPT_MODE, key, inputFile, outputFile);
    }

    private static void doCrypto(int cipherMode, String key, File inputFile,
            File outputFile) throws CryptoException {
        try {
            Key secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
            Cipher cipher = Cipher.getInstance(TRANSFORMATION);
            cipher.init(cipherMode, secretKey);

            FileInputStream inputStream = new FileInputStream(inputFile);
            byte[] inputBytes = new byte[(int) inputFile.length()];
            inputStream.read(inputBytes);

            byte[] outputBytes = cipher.doFinal(inputBytes);

            FileOutputStream outputStream = new FileOutputStream(outputFile);
            outputStream.write(outputBytes);

            inputStream.close();
            outputStream.close();

        } catch (NoSuchPaddingException | NoSuchAlgorithmException
                | InvalidKeyException | BadPaddingException
                | IllegalBlockSizeException | IOException ex) {
            throw new CryptoException("Error encrypting/decrypting file", ex);
        }
    }
}

---

package net.codejava.crypto;

import java.io.File;

public class CryptoException extends Exception {

    public CryptoException() {
    }

    public CryptoException(String message, Throwable throwable) {
        super(message, throwable);
    }

    public static void main(String[] args) {
        String key = "Mary has one cat1";
        File inputFile = new File("document.txt");
        File encryptedFile = new File("document.encrypted");
        File decryptedFile = new File("document.decrypted");

        try {
            CryptoUtils.encrypt(key, inputFile, encryptedFile);
            CryptoUtils.decrypt(key, encryptedFile, decryptedFile);
        } catch (CryptoException ex) {
            System.out.println(ex.getMessage());
            ex.printStackTrace();
        }
    }
}