What is Advanced Encryption Standard (AES)?
Advanced Encryption Standard cryptography is the NIST-standardized symmetric block cipher derived from Rijndael. FIPS 197 specifies AES-128, AES-192, and AES-256; each transforms 128-bit blocks, while the suffix identifies the secret-key length. AES applies a defined sequence of substitutions, permutations, and key-dependent transformations under the same secret key for encryption and decryption. The algorithm alone does not specify key exchange, key storage, padding, a mode of operation, nonce or initialization-vector handling, or message authentication. Those surrounding choices determine whether a system provides only confidentiality or also detects manipulation. AES encryption is reversible with the key, whereas Hashing is a one-way integrity-oriented primitive; the terms are not interchangeable.
What is Advanced Encryption Standard (AES) used for?
AES protects storage, databases, backups, application payloads, Transport Layer Security (TLS), and Virtual Private Network (VPN) or IPsec traffic. Deployment decisions must pair the cipher with an appropriate mode. GCM provides authenticated encryption when its nonce requirements are met, XTS addresses storage-sector encryption, and legacy CBC designs require separate, correctly composed integrity protection. Security also depends on cryptographically secure key generation, KMS or HSM protection, access separation, rotation, recovery, and nonce or IV uniqueness. Implementations should use maintained cryptographic libraries with side-channel defenses rather than bespoke code. Choosing AES-256 does not compensate for exposed keys, repeated nonces, weak entropy, missing authentication, or excessive decrypt privileges; leadership assurance must cover the complete cryptographic system.
