AES-256

AES-256 is the Advanced Encryption Standard using a 256-bit key. It is a symmetric cipher — the same key encrypts and decrypts — and is trusted across the industry for everything from TLS and VPNs to disk encryption. The 256 refers to the key length; a longer key means an astronomically larger space of possibilities, making brute force infeasible with any foreseeable technology. AES is a block cipher, so it is paired with a mode of operation (commonly GCM, which also authenticates the data) to encrypt streams of real-world traffic safely.

A VPN profile's protocol determines its cipher. WireGuard uses ChaCha20-Poly1305, not AES-256. AES-based configurations need authenticated encryption and sound key handling. Forward secrecy addresses later long-term-key compromise under its assumptions; leaked traffic keys remain dangerous. See the WireGuard protocol reference.

ChaCha20-Poly1305 and AES-GCM provide authenticated encryption in different protocols. Forward secrecy depends on key exchange and secret handling, not AES key length. For the s4m VPN, check the issued protocol and client configuration; long-term-key compromise and traffic-key disclosure are different risks.