How to Encrypt Strings in Java for Barcode Security

How can I easily encrypt a string in Java for use in a 2D barcode (PDF-417) while ensuring secure but simple decryption?

Encrypting strings in Java is crucial for ensuring that sensitive information remains protected, especially when using formats like PDF-417 for barcodes. The goal is to adopt a simple encryption method that’s easy to implement, yet securely hides the data from unauthorized users. Below, we’ll explore a straightforward approach using the AES algorithm, which doesn't require complex infrastructure like RSA key pairs or PKI.

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class SimpleEncryption {
    private static final String ALGORITHM = "AES";
    
    public static byte[] encrypt(String data, String key) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        return cipher.doFinal(data.getBytes());
    }

    public static String decrypt(byte[] encryptedData, String key) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        return new String(cipher.doFinal(encryptedData));
    }
} 
// Example Usage: 
String key = "1234567890123456"; // 16 chars for AES-128 
byte[] encrypted = encrypt("Hello World!", key);
String decrypted = decrypt(encrypted, key);  // matches "Hello World!"

Causes

• Need for data confidentiality when using barcodes.
• Protection against unauthorized access to sensitive information.
• Requirement for simple encryption and decryption process.

Solutions

• Use the AES (Advanced Encryption Standard) for string encryption, which involves symmetric key encryption.
• Utilize the Java Cryptography Architecture (JCA) for easy implementation without complex overhead.
• Provide a simple key for decryption that can be shared with authorized companies.

Mistake: Using an inadequate key size for AES.

Solution: Make sure to use a key of at least 128 bits (16 characters). For better security, use 256 bits.

Mistake: Hardcoding sensitive keys in source code.

Solution: Store keys securely, for example, using environment variables or secure key management services.

Mistake: Not using a secure random generator for keys.

Solution: Use KeyGenerator or secure random libraries to generate keys dynamically.