How Does Encryption Secure Your Data in VPNs? A Technical Dive

Virtual private network providers make a big deal about protecting you from cyber threats and all kinds of snoops by using the most advanced encryption available. But what does that mean exactly? What is encryption, and how does it let VPNs make do with their promises? Join us in taking a peek “under the hood” to discover how and why encrypting your data makes a world of difference. 

Putting the P in Private

A core VPN feature is routing a connection through any server in a worldwide network. It makes VPNs similar to proxies in that you can access content from country A as though you were in country B without geographical restrictions or compromising your IP address.

However, using a proxy server alone does nothing to protect the data you exchange and provides only limited anonymity. Conversely, encryption addresses two crucial problems internet users face today. 

On the one hand, encryption keeps your data safe. It prevents hackers who may be monitoring internet traffic from recognizing and exploiting crucial information like passwords, credit card numbers, or personal details.

On the other, using a VPN makes your online activities anonymous. Going online without a VPN’s protection exposes everything you do to your ISP. Connecting requires that each device have an identifiable IP address. Your ISP, advertisers, and criminals can use this address to profile you based on your activities.

Accessing the internet conventionally takes away your right to choose whether to disclose such information. VPNs restore that right, which wouldn’t be possible without encryption. 

What Is Encryption? 

Encryption is the act of scrambling data so that its real meaning becomes hidden. The original data looks like ordinary text or plaintext. Anyone who knows how to read can. Encrypting it turns the plaintext into cyphertext that looks like gibberish. Someone could still intercept and look it up, but they’d get no use out of it. Encryption is essential for limiting access to such data only to trusted parties who can unscramble or decrypt it with an agreed-upon key.

Think of encryption keys as specific bits of information senders use to encrypt data and provide a solution that allows only recipients to access it. VPNs use two encryption types.

Symmetric encryption is more straightforward since a single key can encrypt and decrypt data. It requires that both parties trust each other, though. Asymmetric encryption is more advanced and uses two connected keys. The recipient makes a public key available, which the sender uses to encrypt their data. This public key pairs with a private key only the recipient knows. That private key is the only means of decryption. 

How Do VPNs Encrypt Data? 

When using a VPN, all the data you exchange with the internet benefits from encryption. The process starts by connecting your VPN client to a remote server using a secure protocol. Most modern VPNs use OpenVPN protocol since it’s the most secure. However, users might also choose protocols like WireGuard for less latency & when gaming or IKEv2/IPsec when connecting from a mobile network.

The client, i.e., the VPN software running on your PC, phone, or router, then encrypts all the data you send. First, it establishes a link to a VPN server. They use asymmetric encryption to exchange public keys and verify connection security.

Symmetric encryption then adds an extra protective layer should the first one fail. A new key is created during this step for each connection. The VPN’s encryption algorithm uses that key to encrypt the data. Most VPNs use a form of AES-256, a cipher that splits any encrypted message into 256 blocks. It would take current supercomputers billions of years to crack, and a speedier method has yet to appear.

Your data is already useless to ISPs or hackers at this stage. It has to travel to the server for your request to go through, which requires splitting it into packets. Each packet gets another encryption layer during transit to stop any interception attempts. This establishes the secure "tunnel" VPNs often refer to.

The VPN server decrypts your request once it arrives and forwards it to websites, streaming services, etc. The request looks like it came from the VPN server’s address, while yours has no association with it. The recipient processes the request and sends a response to the VPN server, which encrypts it and sends it back to you. 

Make the Right Choice

Our explanation applies to reputable VPNs that take their customers' safety and anonymity seriously. Less scrupulous and especially free providers may not offer adequate protection. Worse yet, some actively harm users by providing weak or no encryption or selling the info they thought was safe to others. You may want to check out sources like the VPN comparison table for more information. 

Now that you know how VPN encryption works and benefits you, make sure you also go with a reputable provider that puts what you've learned into practice.