AES Symmetric Encryption
Encrypt and decrypt sensitive data with AES/CBC/PKCS5Padding using Java's javax.crypto API.
Symmetric vs Asymmetric Encryption
Symmetric encryption uses the same key for encrypt and decrypt (fast, suitable for bulk data). Asymmetric uses a public/private key pair (slower, used for key exchange and signatures). AES is the standard symmetric cipher.
AES Modes: CBC vs GCM
AES has several modes. AES/CBC/PKCS5Padding is common but lacks authentication. AES/GCM/NoPadding provides both encryption and authentication (AEAD) — strongly preferred for new code.