AEAD
also: Authenticated Encryption with Associated Data
AEAD (Authenticated Encryption with Associated Data) is a cryptographic mode that simultaneously encrypts data and verifies its authenticity and integrity, protecting against tampering.
AEAD combines encryption and authentication into a single operation, ensuring that data is both confidential and authentic. Unlike traditional modes that encrypt first then authenticate separately, AEAD does both at once, making it faster and reducing implementation errors.
Common AEAD modes include AES-GCM (Galois/Counter Mode), AES-CCM, and ChaCha20-Poly1305. You provide plaintext, an encryption key, and optionally "associated data" (headers or metadata that authenticate but aren't encrypted). The cipher outputs ciphertext plus an authentication tag.
Example: HTTPS/TLS 1.3 uses AES-256-GCM to encrypt and authenticate every packet. If an attacker modifies even one bit of ciphertext, the authentication tag will be invalid and the decryption will fail, preventing silent corruption.