AES-GCM
AES in Galois/Counter Mode
It is the most widely used AEAD, and every message under one key needs a unique 96-bit nonce: a repeated nonce exposes the XOR of the two plaintexts and lets an attacker forge tags, and with random nonces one key should encrypt at most 2^32 messages.
- Also called
- GCM · Galois/Counter Mode · AES-256-GCM · AES-128-GCM
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.
ECB mode: why it leaks patterns and what to use instead
Derive exactly what ECB reveals and why a longer key cannot fix it, find where ECB enters real code, and replace it with an authenticated mode.
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