AES CBC vs GCM in Spring Boot: Which Mode Should You Choose?

for free reading -> https://erkanyasun.medium.com/aes-cbc-vs-gcm-in-spring-boot-which-mode-should-you-choose-1adb3de475ac?sk=a39c2504a0df4d1673633ea8dca06eb0

Encryption can be tricky in any Java-based application, including Spring Boot projects. If you’ve come across AES (Advanced Encryption Standard), you might be wondering about the difference between CBC (Cipher Block Chaining) and GCM (Galois/Counter Mode). Let’s do a quick overview, outline best practices, and highlight libraries you might use.

AES CBC (Cipher Block Chaining)

How it works

• Data is split into fixed-size blocks.
• Each block is XORed with the previous encrypted block, making it dependent on all previous blocks.
• Requires an Initialization Vector (IV) to kick things off.
• No built-in authentication — you often need an HMAC to ensure integrity.

Pros

• Widely supported and historically used in many applications.
• Straightforward to implement with standard Java libraries.

Cons

• Vulnerable to padding oracle attacks if not used correctly (e.g., no padding or partial checks).
• Lacks built-in authentication; you need an additional HMAC or MAC for integrity checks.

AES GCM (Galois/Counter Mode)