CryptoUtil.java

/*
Project: Simple Password Vault in Java
Structure:
- src/
  - CryptoUtil.java
  - PasswordVault.java
  - Main.java
- vault.txt (created automatically)
*/

// CryptoUtil.java
import javax.crypto.*;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

public class CryptoUtil {
    private static final String ALGORITHM = "AES";

    public static String encrypt(String data, String key) throws Exception {
        SecretKey secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] encVal = cipher.doFinal(data.getBytes());
        return Base64.getEncoder().encodeToString(encVal);
    }

    public static String decrypt(String encryptedData, String key) throws Exception {
        SecretKey secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        byte[] decodedValue = Base64.getDecoder().decode(encryptedData);
        byte[] decValue = cipher.doFinal(decodedValue);
        return new String(decValue);
    }
}