AEAD
Authenticated encryption with associated data
It encrypts the plaintext for confidentiality and authenticates both the ciphertext and associated data sent in the clear, so decryption fails if either was changed (RFC 5116).
- Also called
- authenticated encryption
- Defined in
- RFC 5116
Covered in
AEAD records: AES-GCM nonces, associated data and key limits
Build an encrypted record whose tag binds ciphertext to the intended tenant, record, purpose and format, keep nonces unique within each key’s usage limit, and verify the design with actual AES-GCM.
Choose cryptographic algorithms and parameters by job
A sourced quick reference for October 2026: which algorithm and parameters to use for encryption, hashing, passwords, MACs, signatures, key agreement, key derivation, randomness and TLS, the matching APIs in Node.js, Python, Java, Go and .NET, and where post-quantum migration stands.
Padding oracle attacks
Use a byte-level CBC example to see how a tiny validity signal becomes plaintext information, then design verification that checks more than the error message.
Practice: AES-GCM nonce reuse lab: Fix a nonce allocator that breaks after restart · Insecure randomness lab: Generate unguessable API keys · Local project: Bind ciphertext to the correct record