How Does Encryption Work in VPNs?

Keeping secrets has always been crucial to have an advantage over enemies, competitors, or criminals. It’s also a key to maintaining your privacy.

During any communication, confidential information must be protected from being read. This is where ciphering comes in. All sorts of ciphers and a long list of mathematical tricks were invented throughout history to prevent information theft.

We have previously discussed how VPNs route your traffic through another IP address to make you near anonymous. But have you wondered how a VPN encrypts your traffic? How does it protect your communication from discovery and potential interception?

In this article, we’ll see what happens in a nutshell, how VPN encryption works, and how TuxlerVPN does it better to protect your privacy.

Does VPN Encrypt Data?

Yes, of course! Any service that proudly names itself ‘VPN’ must necessarily use encryption. What if it doesn’t? Well, if you try to make a cup of tea without water – can you call it ‘tea’? So yes, VPNs do encrypt data by definition.

The ‘P’ in VPN stands for ‘private.’ It means that the network (and the tunnel) must not be subject to unauthorized access. This brings about the necessity of data flow protection, therefore encryption. So if a system doesn’t offer such safety, naming it ‘VPN’ is misleading.

VPN Encryption: Why Do You Need It?

Before we dive into the miracles of VPN encryption, let’s first understand its importance in online security.

As we have noted before on the TuxlerVPN blog, a VPN has two chief purposes. The first one (and the more important one) is to hide your web location (i.e., the IP address) by routing all your traffic through another IP. This separates you from your web activity, thus making you anonymous to an extent. 

Secondly, a VPN should cover your web traffic so that your communication stays protected and “unreadable” should there be an interception. Your ISP, law enforcement agencies, or cyber frauds may have reasons to intercept your communication and access your web activities. VPN encryption should thwart any such attempts.

VPN Encryption: How Does It Work?

The process of encryption involves scrambling an input such as your web traffic, an email communication, or file information into an unreadable format. This is called a ciphertext, and it blocks illegal and unspecified access. In a VPN, this ciphertext then travels through a tunnel (this is where the routing takes place) and reaches your destination, where it’s decrypted for consumption by the recipient. 

This process of scrambling content into ciphertext is governed by the protocol used by the VPN. As we have discussed before, there are several types of VPN protocols, such as OpenVPN, PPTP, and WireGuard. These protocols also influence the authentication required to carry out encryption and decryption. This is done using an encryption key or an algorithm – a series of numbers used to encrypt and decrypt the content of a communication.

Some of the most common encryption algorithms are DES, RSA, and AES. Out of these, AES is the most advanced and secure. Many VPN services use it. It uses three key lengths: 128, 192, and 256 bits. The longer the key, the more secure encryption is because it takes longer to guess the key. All these types offer very strong protection, but the 256-bit safety is considered military-grade and redundantly tough.

There is still a lot more technical operation that goes behind the encryption models of VPNs. But the premise involves using a VPN protocol to govern the encryption and decryption of your web traffic to move it securely over the web.

How strong is the VPN encryption?

To give an idea of how strong modern encryption is, let’s consider how long it would take to succeed in a brute-force attack on AES-128. There are 2¹²⁸ possible keys, and a hacker just has to keep trying them one by one. Let’s think he harnesses a supercomputer capable of trying a billion billion keys every second, which is currently pure science fiction. But let’s add even more: a lottery winner’s luck, so that odds of one in a million is enough. Then it would take…

2128109109106606024365= 10 790 283 years.

With unbelievable luck and huge technological advantage – over ten million years to crack a single code! And it’s about the weaker variant. No wonder the underlying algorithm (Rijndael) was the winner of the 1997-2000 competition organized by the US government’s National Institute of Standards and Technology (NIST). Nowadays, it is considered the best VPN encryption there is. Other methods are still in use. For example, the Blowfish algorithm is default in the popular OpenVPN protocol.

As you see, brute force attacks are pointless. However, mathematicians have been striving to find smarter ways to exploit any weaknesses of popular encryption methods. So far, without much luck – and it’s been over 20 years. Several academic attacks have been reported, but they are impractical. If we assume that a ‘breach’ makes AES 1000 times easier to crack, then it still would take 10 000 years. It’s enough to publish a paper that’s interesting for experts. It’s very far from enough to claim that AES is truly broken.

VPN encryption types

There is one point where the above strength cannot be applied. To explain it, we must introduce the two types of modern encryption.

1. Symmetric cryptography. Here encryption and decryption require the same cryptographic key. It must be kept private, known only to the two sides of the connection. It’s like sending a letter in a locked chest, where the sender and receiver must possess identical keys. If they’re compromised, then the message isn’t safe anymore and can’t be trusted. What if someone grabbed it, opened it, changed the contents, and then sent it further? An example here is AES. Such ciphers are relatively fast. But they have an inherent flaw. When establishing a secure connection, the keys cannot be safely distributed without a secure connection already existing.
2. Asymmetric cryptography. It uses two kinds of keys. The public one is used only for encryption when sending the message. It’s safe to disclose it to anyone. The second key is private and used only for decryption when receiving the transfer. Only one endpoint of the connection, like an encrypted VPN app, can know this key. To maintain security, it cannot be sent anywhere, ever. The two keys are mathematically related, but it’s almost impossible to calculate the private one based on the public one. The underlying principle is large number factorization. You can multiply two large prime numbers very fast. But finding the factors when knowing their product is extremely time-consuming. An example of an asymmetric cryptography algorithm is RSA, used in the TLS protocol. These methods are significantly slower than symmetric ones. But they don’t need an existing secure link to set up the connection.

Many secure network protocols use both types of cryptography. The asymmetric one is employed during the handshake – the preparation phase. Its point is to generate and safely exchange the secret key for the upcoming symmetric encryptions. Then, the actual communication can begin. It uses symmetric cryptography for speed. The key is trustworthy because it was distributed via a temporarily existing secure connection. Such cryptographic cooperation is especially useful in VPN systems. 

VPN encryption protocols

Every VPN system employs a set of rules to manage data transfer safely and efficiently. It’s called a VPN protocol. As already pointed out, it must incorporate both tunneling and encryption. Despite such requirements, not all tunneling protocols in modern VPNs are encrypted. How can this be?

Many solutions apply more than one protocol to sustain a VPN connection. One is responsible for constructing the tunnel, other secure it with authentication and encryption. Such systems include:

1. PPTP with PPP (Point-to-Point Tunneling Protocol with Point-to-Point Protocol). It was historically important in the oldest VPN solutions. Later it had been found too insecure to be trusted by modern respectable VPNs.
2. L2TP/IPSec (Layer 2 Tunneling Protocol/Internet Protocol Security). IPSec encrypts every IP packet, thus securing the system. This technology superseded PPTP and nowadays is regarded as safe.
3. IKEv2/IPSec (Internet Key Exchange version 2 with IPSec, abbreviated to IKEv2). This combination is often applied on mobile devices. Its auto-reconnect feature allows it to sustain the connection when changing the network.

There are also technologies working as a single protocol with security features included. For example, OpenVPN is known for its openness, safety, and configurability. Its encryption parameters are highly configurable, but this protocol requires more expertise than others to set up. WireGuard is one of the newest VPN technologies. It was designed with several goals: high performance, ease of use, quick setup, and top security. In 2020, it was incorporated into Linux.

When you use your VPN app (be it on Windows or Mac), a lot is happening with your data transfer. Modern encryption algorithms are an impressive achievement of human thought. Whole generations of very smart people have been striving to create ingenious processes. They have evolved to be fast as a blink of an eye and strong like an underground vault from Fallout Shelter. Their mathematical intricacies are very complicated, yet software developers create applications that hide the complexity behind a user-friendly interface. Thanks to the cooperation between academics and programmers, you can enjoy surfing the Internet easily and safely!

If you are looking for options, consider TuxlerVPN’s residential IPs and military-grade encryption. Download today!

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