AES-GCM
More info
- Creator
- McGrew & Viega
- Released
- Type
- AEAD mode
- Spec
- NIST SP 800-38D
- Wikipedia
- en.wikipedia.org
AES in Galois/Counter Mode — authenticated encryption with associated data (AEAD) that delivers confidentiality and integrity in a single operation.
Counter mode for parallelisable encryption + GHASH for the MAC. Default AEAD in TLS 1.2/1.3, IPsec, SSH and Signal. NIST SP 800-38D. Key sizes 128/256 bits; nonce must be unique per key — reuse a nonce and the entire authentication collapses (the classic footgun).
Alternatives: ChaCha20-Poly1305 is often faster in pure software on CPUs without AES-NI (phones, embedded), and AES-GCM-SIV is nonce-misuse-resistant.