Course

The "Secure.java" code snippet provided in this challenge demonstrates the encryption of a string using the AES algorithm in GCM mode. The method `encryptStr` decodes a Base64 string to generate a secret key and uses a fixed initialization vector (IV) composed of null bytes for encryption. The `encrypt` method sets up the cipher in AES/GCM/NoPadding mode and returns the encrypted byte array.

However, a critical security flaw exists in the use of a fixed IV. GCM mode relies on the randomness of the IV (or nonce) to ensure the security of the encryption. A fixed IV undermines this security, allowing an attacker with access to multiple encrypted messages to potentially decrypt them using XOR operations. This highlights the importance of using a random IV in secure encryption practices.