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What Makes a VPN Secure?

Updated on October 7, 2015

Keeping Data Secure

The internet has become an integral tool in both the business world and in our personal lives. More and more of us are using the internet to work from home or while we are on the go. We are also using the internet to manage our finances with online banking, to keep in contact with friends and family, and to shop for products and services. With so much of our lives depending on the internet it is hugely important that we keep private or personal data away from snoopers and prying eyes. Whether you want to connect securely to your office network from home or simply want to keep your personal data secure, a good option is to use a VPN. But how exactly does using a VPN keep your data secure?


What is a VPN?

A VPN is a ‘virtual private network’. It allows you to use a public network, like the internet, but with the security of a private network. Because of the security measures in place with a VPN it can be difficult for a hijacker to take control of the data your computer is transmitting and even if they could take control they would be unable to understand or do anything with the data. The reason for this is because of the two main security measures used by VPNs – tunnelling and encryption.


Encryption & Cryptography

Encryption, and by extension cryptography, has been used for thousands of years – it is not a new concept though the techniques have changed over the centuries. Cryptography, the practice and study of secure communication, involves the conversion of messages into an incomprehensible format at one end, by the sender, and the conversion back to a comprehensible form at the other end, by the recipient. Early forms of encryption were done by hand but mechanical encryption devices were invented by the early 20th century. Today, encryption and decryption is done by computers. You can use encryption to protect files on your computer and stop people from accessing things they shouldn’t – with encryption only a machine or individual with the right ‘decoder’ can access the data.


Symmetric Key vs. Public Key

With a VPN the data being transmitted and received is encrypted to stop any unauthorised access and stop hijackers from being able to use your data. Computer encryption uses ‘keys’ to encrypt and decrypt information. An encryption key is essentially a small piece of text code that tells the computer what it needs to do to encode or decode the data. There are two main types of encryption – symmetric-key and public-key. With symmetric key encryption the sender and the recipient use the same key to encrypt and decrypt the data. If you use symmetric key encryption a method of exchanging the key in a secure way must be used.

Public key encryption, on the other hand is particularly well suited for transmitting information over the internet. With this system each computer has a public key, which is known to everyone, and a private key, which is only known to that specific computer. The public key is used to encrypt the data and the corresponding private key is used to decrypt it. So, the sender will use the recipient’s public key encrypt the information they want to send, the recipient will then use their private key, that only they know, to decrypt it. As it is impossible to work out the private key if you know the public key it means that public keys do not always have to be exchanged in secure environments.



Though encryption is an important part of VPN security it is best used in conjunction with another security measure – tunnelling. Through the use of tunnelling a private network is effectively created within a public network like the internet. When a computer sends data it breaks the data down into packets – this means that any email you send is broken down into packets when it is sent and any webpage you view is received in packet form by your computer. With tunnelling the packets that your computer is sending and receiving are ‘encapsulated’. Encapsulation is where a packet is placed inside another packet before it is sent over the internet. Encapsulating packets gives them an extra layer of security by ‘hiding’ the contents from public view. The encapsulated packets are essentially moving inside a virtual tunnel – hence the name.

Virtual Private Networks will use a combination of encryption and tunnelling to hide your data from public view and to encode it – using both these measures means that your data is much more secure than if you sent it without a VPN. In order to use encryption and tunnelling a VPN will utilise different ‘protocols’. A protocol is an agreed-upon format for sending and receiving data and it is what tells your computer when to use encryption or encapsulation. The protocols most commonly used by VPNs are IPsec, L2TP and PPTP amongst others.


Security Protocols

IPsec is a protocol used to encrypt data. It has two modes of operation – transport mode and tunnelling mode. In transport mode the protocol will only encrypt the packet message while in tunnelling mode the protocol encrypts the whole data packet. Often VPNs will use IPsec in tunnelling mode and it can be used in combination with other security protocols. Some VPNs will use IPsec as the complete security protocol, while others may use IPsec just as the encryption protocol. L2TP (or Layer 2 Tunnelling Protocol) and PPTP (Point-to-Point Tunnelling Protocol) are both protocols used in the tunnelling process. There are differences between the two protocols but in basic terms they both encapsulate data and create ‘tunnels’. Neither L2TP nor PPTP can encrypt data so they are both often used in conjunction with an encryption protocol like IPsec.

What Makes a VPN Secure?

Virtual Private Networks are a useful way of keeping personal or confidential data secure from unauthorised access. VPNs are used by offices and individuals alike and are often quick and simple to set up. What keeps your data secure are the security protocols that encrypt and encapsulate the data – these protocols allow your data to be sent securely over a private network, encoded and hidden from public view.

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    tom tomesian 4 years ago from usa

    nice post.