What Is AES-256?
AES (Advanced Encryption Standard) is a symmetric block cipher adopted by NIST in 2001. AES-256 uses a 256-bit key, meaning there are 2^256 possible key combinations — brute-forcing it would require more energy than exists in the observable universe.
AES operates on fixed 128-bit blocks through 14 rounds of transformations. It is used by the U.S. government to protect classified information up to TOP SECRET level.
AES-256 vs ChaCha20
Both provide 256-bit security. The key difference: AES requires dedicated hardware instructions (AES-NI) for safe, high-speed operation. Without hardware acceleration, software AES can be vulnerable to timing side-channel attacks. ChaCha20, used by WireGuard and VPNWG, is designed to be fast and secure in pure software.
AES-256 in the VPN Industry
AES-256-GCM is commonly used by OpenVPN and IKEv2. WireGuard's choice of ChaCha20-Poly1305 provides equal security with better performance on mobile devices. See our encryption comparison.