Java String Encryption for Secure 2D Barcodes

Overview

The objective is to encrypt a string to be displayed in a 2D barcode (PDF-417) in a manner that prevents unauthorized access to the data upon scanning. The encryption should meet specific criteria:

• Simplicity
• No complex infrastructure (RSA, PKI, key pairs)

Approach

Block Ciphers:

Begin by selecting a symmetric key Block Cipher, such as AES 256, known for its high security.

Encryption Modes:

Utilizing a suitable Encryption Mode is crucial. Avoid ECB mode due to its vulnerability to data patterns. Consider CTR or CBC modes for better security.

Nonces and IVs:

Generate unique random Nonces (Initialization Vectors) for each encryption to prevent repetitive IV usage, which compromises security.

Hashing:

To protect against data manipulation, consider using GCM mode, which includes a hash signature to verify the integrity of the encrypted message.

Implementation

Google Tink Library:

For secure and simplified implementation, leverage Google's Tink library, which offers AES-GCM encryption and manages key generation securely.

AES-GCM Mode:

Set the encryption mode to "AES/GCM/NoPadding" to benefit from its hashing and authentication features.

Key Generation:

UseTink's key generation methods instead of relying on user input (passwords) to ensure sufficient entropy and security.

Android Considerations:

Be mindful of potential reverse engineering when storing passwords in plaintext for Android apps. Consider Asymmetric Cryptography for increased security.

Conclusion

Following these guidelines and utilizing the Google Tink library enables you to securely encrypt strings for 2D barcodes, protecting sensitive data from unauthorized access upon scanning.