What Is Encryption? A Beginner's Guide to AES-256 and VPN Security
Learn how encryption works, the difference between symmetric and asymmetric encryption, and how WireGuard's ChaCha20 cipher keeps your Nexun VPN traffic private.
What encryption actually does
Encryption converts readable data into an unreadable scramble that only someone with the correct key can decode. Every time you connect to a website over HTTPS or use a VPN, encryption is running silently in the background. Without it, anyone on the same network -- a cafe Wi-Fi, a hotel router, or your ISP -- could read your traffic in plain text.
Symmetric vs asymmetric encryption
Symmetric encryption uses one shared key to both lock and unlock data. It is fast and ideal for bulk data like VPN tunnels. AES-256, the gold standard used in banking and government systems, is symmetric -- a 256-bit key creates so many possible combinations that brute-forcing it would take longer than the age of the universe. Asymmetric encryption uses a key pair: a public key anyone can use to encrypt, and a private key only you hold to decrypt. It is used during the handshake phase of secure connections to exchange symmetric keys safely.
How a VPN encrypts your traffic
When you connect through a VPN, your device and the VPN server first perform an asymmetric handshake to agree on a shared session key. After that, all your traffic is wrapped in a symmetric encrypted tunnel. An ISP or eavesdropper sees only encrypted packets addressed to the VPN server -- they cannot read the destination URLs, your login data, or anything you send or receive.
WireGuard and ChaCha20: what Nexun uses
Nexun is built on WireGuard, a modern VPN protocol designed to replace older, heavier alternatives. Instead of AES-256, WireGuard uses ChaCha20-Poly1305 -- a cipher that is equally secure but faster on devices that lack dedicated AES hardware, such as budget Android phones and older ARM processors. ChaCha20 is also resistant to timing attacks that can sometimes weaken AES in software implementations. The result is strong encryption with lower battery drain and faster connection times.
Why local privacy laws make encryption essential
The GDPR, which applies across the EU, treats encryption as a key technical measure for protecting personal data. Article 32 explicitly requires organizations to implement 'appropriate technical measures' including encryption where feasible. Dutch law reinforces this through the Autoriteit Persoonsgegevens, which has fined companies for transmitting personal data without proper encryption. For everyday users, this legal context matters: it means your ISP and any service you use should be encrypting your data -- and a VPN adds a layer of protection in cases where they fall short.
FAQ
Is AES-256 stronger than ChaCha20?
Both are considered equally secure for practical purposes. AES-256 has a longer track record, while ChaCha20 performs faster on devices without hardware acceleration and is less vulnerable to certain timing attacks. Nexun uses ChaCha20 via WireGuard because it offers strong security with better performance across a wide range of devices.
Can my ISP see what I do when I use Nexun?
No. When connected to Nexun, your ISP only sees encrypted traffic between your device and the Nexun server. They cannot see which websites you visit, what you download, or any content you send or receive. Your real IP address is also hidden from the sites you visit.
Does encryption slow down my internet connection?
Modern VPN encryption has minimal impact on speed for most users. WireGuard is specifically designed to be lightweight -- its codebase is roughly 4,000 lines compared to tens of thousands for older protocols. On fast connections, the speed difference is usually imperceptible. On older hardware or mobile devices, ChaCha20 is particularly efficient and preserves battery life better than alternatives.