VPN Encryption Protocols & Standards explained

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With the increasing threats of cyber-attacks, the dire need for encryption and tough security measures increases with each passing day. In this complete VPN encryption protocols guide, let’s take an in-depth look at what encryption is and how various VPN encryption protocols use it in providing a secure VPN connection to their users. 

So, let’s get started.

What is Encryption?

Encryption is defined as a method of converting data from a readable format to an encoded and unreadable format with the help of different algorithms.

VPN encryption is a means of encrypting plaintext data such as online traffic to ensure that it shows up as indecipherable gibberish to anyone who tries to monitor your traffic and online activities.

VPN encryptions enable protecting sensitive information like bank account details, credit card numbers, and login credentials from cybercriminals. It does so because they won’t be able to spy on your internet connection when you use public Wi-Fi.

Besides this, VPN encryption also ensures that your internet activities can’t be monitored by advertisers, ISP, and the government.

What are the Encryption Keys?

A VPN encryption key is a randomly-generated string of bits used to encrypt and decrypt the data. Each encryption key is developed uniquely. The length of the encryption key is calculated in bits. The longer the key, the stronger the level of encryption is.

The size of the encryption is varying. For instance, it can be –bit, which allows only two possible combinations, or 256-bit, allowing 10^77 combinations.

There are two kinds of encryption keys that are used in the encryption and decryption process. One is known as the Public key, and the other is the Private Key.  The Public Key is available through a public directory, while the private key remains confidential and is known by the key owner. 

VPN Encryption Protocols:

A VPN protocol is a set of orders and instructions to exchange a secure and encrypted connection between the two systems. Commercial VPN services commonly support various VPN encryption protocols. Among all, there are five notable VPN protocols, which are as follows:

  • PPTP
  • L2TP/IPSec
  • SSTP
  • IKEv2
  • OpenVPN

Now, let’s discuss each VPN encryption protocols in detail:

Point-to-Point Tunneling Protocol (PPTP):

The PPTP is the standard protocol for corporate VPN networks. It requires both the GRE protocol and TCP port 1723. It is easy to firewall GRE, which makes it trouble-free to block the PPTP connections. Also, it is available as a standard protocol on every VPN-capable device and platform. 

PPTP is easy to set up, and you don’t need to install any additional software too. It shows that PPTP remains a popular choice for both business and commercial VPN services. Moreover, it has the benefit of requiring low computational overhead to implement; therefore, it provides a quick connection.

 As PPTP is only a VPN protocol, it depends on different authentication methods to provide security to the users. However, experts, after testing this protocol, conclude that PPTP is not secure at all. Though it is now found using a 128-bit encryption key, several security vulnerabilities were associated with it since it first came to light.

The most serious among them was the possibility of un-encapsulated MS-CHAP v2 Authentication. Using this feat, PPTP has been broken within two days. Secondly, it can easily get compromised by NSA and other intelligence agencies, although Microsoft has fixed this flaw but has recommended using either SSTP or L2TP/IPsec instead. 

Pros:

  • Easy to set up
  • Supported by all platforms

Cons:

  • Easily blocked
  • Low level of security
  • Compromised by NSA

L2TP/IPsec:

Layer 2 Tunneling Protocol (L2TP) is built-in in almost all the latest operating systems and capable VPN devices. The L2TP, on its own, does not provide any confidentiality and encryption to internet traffic, which passes through it. For this reason, it is implemented with the IPsec authentication suite (L2TP/IPsec). 

L2TP/IPsec can use any of the AES or 3DES ciphers. The 3DES is vulnerable to Meet-in-the-middle and Sweet32 collision attacks. The only problem with using this protocol is that it uses a limited number of ports. It results in complications when used behind the NAT firewalls. The reliance on fixed ports makes the protocol quite easy to block.

L2TP/IPsec captures the data twice, which ultimately slows down the connection. It is offset by the fact that both encryption and decryption occur in the kernel, and L2TP/IPsec also allows multi-threading, which OpenVPN doesn’t allow. Thus, L2TP/IPsec is much faster than OpenVPN.

The L2TP/IPsec using the AES cipher has no significant vulnerabilities. However, experts hinted that the standard being compromised by the NSA.

Regardless of some theoretical issues, L2TP/IPsec is secure if the openly published pre-shared keys are not used. Its built-in compatibility with many devices makes it the right choice.

Pros:

  • Supported by Microsoft
  • Very secure
  • Can surpass firewalls

Cons:

  • Don’t have high speed
  • Proprietary standard owned by Microsoft

Secure Socket Tunneling Protocol (SSTP):

Microsoft introduced the protocol in Windows Vista SP1. Even though it is now available for Linux and Mac OS X, it remains a Windows platform. It is a type of encryption protocol that uses SSL 3.0 and offers similar advantages to OpenVPN. SSTP can use TCP port 433 to avoid censorship. Moreover, tight integration with windows can make it quite comfortable to use.

SSTP gets configured with AES encryption. Therefore, it is much more secure and a better option than many other VPN protocols, particularly the PPTP protocol. It uses SSL v3 and avoids any NAT firewall blocking issues. 

It uses the same verification method as that of SSL/TLS. For any data or traffic to transmit at both ends of the connection, it must be verified with a secret key. In this way, you can establish a secure connection. 

But, SSTP is a proprietary standard owned by Microsoft. It means that the code is not open to public scrutiny. Another major issue associated with SSTP is that SSL v3.0 is vulnerable to a Poodle attack. Either this issue affects SSTP or not remains unclear, but again, it hardly inspires confidence. 

As a whole, SSTP provides many of the advantages of OpenVPN. But, being a proprietary Microsoft standard, it severely undermines its credibility.

Pros:

Cons:

  • Vulnerable to certain attacks

Internet Key Exchange version 2 IKEv2:

Cisco and Microsoft developed the IKEv2 protocol. It is not common as L2TP/IPSec doesn’t have support on a few platforms. However, it is considered good, if not superior, to L2TP/IPSec in terms of security, speed, stability, and ability to establish a connection.

It uses AES encryption, and the most significant advantage of using this protocol is its stability. IKEv2 continues to work mechanically after there’s an interruption in the connection. Moreover, it also includes a power outage, especially if you’re using it from your laptop. 

IKEv2 is a tunneling protocol. It becomes a VPN protocol when combined with an authentication suite like IPSec. It is an excellent choice for automatically re-establishing a VPN connection when users temporarily lose their internet connections. For instance, entering or leaving a train tunnel. 

Furthermore, because it supports the Mobility and Multihoming protocol, IKEv2 is resilient to changing networks. This characteristic makes it an excellent choice for cell phone users who regularly switch between home Wi-Fi and mobile connections, or even someone who moves between hotspots.

Pros:

  • Supports a wide range of encryption protocols
  • Easy to set up and use
  • Offers a high level of security

Cons:

  • Supports limited platforms
  • Firewalls can block it

OpenVPN:

It is an open-source technology that uses the OpenSSL library and TLS protocols, and a combination of other technologies to provide a reliable VPN solution. Several VPN services today use OpenVPN as the standard VPN protocol.

The major strength of OpenVPN lies in its configurability. Any platform does not support it; however, it is available on most of the platforms through third-party software. This protocol runs best on a UDP port, but it can also run on any other port as well. 

It also includes TCP port 443, and the regular HTTPS traffic uses it. Running OpenVPN over TCP port 443 makes it difficult to reveal the VPN connections apart from the type of secure connections frequently used by banks, email services, and other online retailers. In this way, OpenVPN becomes had to block.

Another advantage of using OpenVPN is that the OpenSSL library provides encryption, which supports several ciphers.

There are no severe vulnerabilities in OpenVPN, which can affect a user’s privacy. However, some weaknesses made OpenVPN servers potentially open to DoS attacks, but these were fixed in OpenVPN 2.4.2.

To sum up, OpenVPN is one of the most secure VPN protocol presents and supported across the VPN industry.

Pros:

  • Functions with different encryption methods
  • Provides high-level of security

Cons:

  • The setup process is technical
  • Depends on third parties for operating

OpenVPN Encryption:

OpenVPN encryption comprises two parts, i.e., control channel encryption and data channel encryption. The data channel encryption efficiently secures your data, while the control channel encryption secures the connection between the system and the VPN server.

The TLS encryption is another name for the control channel encryption. It is because TLS is the technology that negotiates the connection between the computer and the VPN server. It is the same technology that browsers use to negotiate a link to HTTPS encrypted sites.

Control channel encryption comprises of a cipher, hash authentication, and handshake encryption. However, data channel encryption only have a cipher and hash authentication.

Hopefully, now you might better understand what encryption is, VPN encryption protocols, and how to configure your VPN connection properly.