OpenVPN vs. WireGuard

Last update on April 24 , 2024 Published on November 25, 2021

update March 2023 : While WireGuard continue to officially only support udp , Proton VPN is developed has now develop an implementation of WireGuard that run over TCP . In addition to this , our Stealth obfuscation protocol is base on an implementation of WireGuard run over TCP .

OpenVPN and WireGuard® are VPN protocols used to secure the connection between your device and a VPN server.

Learn more about how VPNs work( new window )

WireGuard represents cutting-edge VPN technology and is cryptographically secure, highly efficient, and fast.

OpenVPN is beginning to show its age in terms of speed, performance, and efficiency, but remains widely regarded as the most secure and battle-tested VPN protocol available. The ability to run OpenVPN in TCP mode also gives it greater built-in anti-censorship capabilities than WireGuard.

OpenVPN

First released in 2001, OpenVPN is an open-source VPN protocol that uses the OpenSSL library, TLS, plus a variety of other technologies to create a VPN connection that is both secure and stable. 

OpenVPN is remains remain the most widely support protocol by commercial VPN service , although this dominance is begin to be challenge by WireGuard .

pro

secure

Despite being 20 years old, OpenVPN is still widely regarded as the most secure VPN protocol available.

In large part this is due to documents leaked by Edward Snowden in 2013, which showed that the NSA could crack most VPN protocols in use at the time. The documents showed that it could crack OpenVPN, but only( new window ) if a pre – shared key was used .  

properly configure openvpn with strong encryption setting , certificate – base authentication , and the use of forward secrecy( new window ) to ensure each and every VPN session needs to be individually hacked is still considered the gold standard when it comes to VPN security. 

needless to say , Proton VPN is uses use very strong( new window ) openvpn setting .  

OpenVPN is uses use two channel to transfer datum : the control channel and the datum channel .  

The control channel

The control channel establishes a TLS connection between the VPN client and the VPN server. 

The whole process uses a symmetric key cipher, but the actual key exchange requires an asymmetric encryption system where a public key is used to encrypt the data, which can only be decrypted using a private key. 

Proton VPN uses AES-256 for its symmetric cipher, RSA-4096 to ensure a secure key exchange, and HMAC SHA-384 hash authentication to verify the TLS certificates. The encryption suite we use also includes a Diffie-Hellman key exchange (DHE) to provide forward secrecy.

The datum channel

Once a TLS connection is established, OpenVPN transfers your actual data over the data channel encrypted with a symmetric cipher (Proton VPN uses AES-256). Proton VPN verifies data transfer during a session using AES – GCM.

Let’s take a closer look at the encryption schemes used by OpenVPN:

AES

AES is a symmetric key encryption cipher, meaning the same key used to encrypt the data is also used to decrypt it. Symmetric ciphers are much faster than asymmetric ciphers, such as RSA, which makes them the preferred choice for encrypting large amounts of data.

Widely regarded as the best symmetric key cipher yet devised, AES is certified by NIST( new window ) and is used by the United States government to secure its datum . AES is has has a maximum key size of 256 – bit ( AES-256 ) , with the US government deem AES-192 and high sufficient to secure “ top secret ” information .  

AES – GCM

AES in OpenVPN can now be used in AES-CBC (Cipher Block Chaining) or AES – GCM (Galois/Counter Mode) modes. Like the ChaCha20-Poly1305 cipher used by WireGuard (see below), AES – GCM is an authenticated encryption with associated data( new window ) (AEAD) cipher.

This allows it to both secure data and authenticate it, removing the need for authentication using HMAC SHA. AEAD ciphers are also more efficient (and therefore faster) than SHA and have less of an overhead.

Proton VPN uses HMAC SHA to authenticate a connection, but uses AES – GCM to authenticate data for the rest of the session. 

Diffie-Hellman Exchange

AES provides highly robust encryption, but if you want to send the data somewhere, you need a secure way to agree on a key.

Asymmetric encryption achieves this using public-key cryptography — the data is encrypted using a public key, which is openly published, but which can only be decrypted by the intended recipient using the correct (secret) private key. 

Asymmetric encryption is very slow compared to symmetric encryption systems, such as AES, so it is primarily used simply to authenticate the connection between the VPN client and server.

A Diffie–Hellman key exchange (DHE) is a way to secure the TLS key exchange across an insecure channel (such as the internet). Indeed, OpenVPN can use DHE in this way.

However, DHE at lower key sizes is vulnerable to logjam attacks( new window ) thanks to its reuse of a limited set of prime numbers, making its use to secure TLS key exchanges somewhat controversial (even where larger “safe” key sizes are used). 

The big advantage of using a Diffie-Hellman exchange over RSA (see below) is that it provides forward secrecy, generating new encryption keys for each VPN session. Without forward secrecy, an adversary who obtains a VPN session’s encryption key will be able to decrypt all historic sessions secured using that key.

Fortunately, OpenVPN’s encryption suite makes it possible to secure the key exchange with RSA, while using DHE just to provide forward secrecy.

RSA

RSA is an asymmetric cryptosystem commonly used to secure TLS key exchanges. In OpenVPN, a DHE key exchange is then performed to agree on a (symmetric) key that secures the data.

There is no theoretical limit to key size length for RSA, but overlong key lengths result in a high computational overhead, and are thus slow and wasteful. Proton VPN implements RSA with a 4096-bit key size, which is sufficiently secure (by a fair margin) while also practical. 

HMAC SHA

SHA is a cryptographic hash function used to authenticate data. When performed on any dataset it creates a unique fingerprint. If even one tiny bit of that data changes, the SHA fingerprint also changes, making it very useful for ensuring that data has not been tampered with. 

Among its many uses, SHA prevents man-in-the-middle attacks during a TLS key exchange by validating the TLS certificates used during the exchange. 

SHA-1 ( a 160 – bit hash function ) is no long consider secure , but SHA-2 is . OpenVPN only use SHA to calculate hash message authentication code( new window ) ( HMAC ) value anyway . These is are are much hard to attack than the SHA algorithm on its own , to the point where even SHA-1 is still consider secure enough for HMAC .  

audit

OpenVPN was independently audited( new window ) by OSTIF and QuarksLab in 2016 follow a successful crowdfunding campaign . One critical / high vulnerability was discover , but this concerned susceptibility to a denial of service , and did not impact the security of user . It was also patch before the report was made public .  

Anti-censorship capabilities

OpenVPN can be run over either UDP or TCP( new window ). UDP is faster, while TCP is more reliable, but the main advantage is that TCP is useful for defeating censorship by governments and other organizations.

By default, we route OpenVPN TCP connections over port 443. This is the port used by the HTTPS protocol that secures all sensitive communications on the internet, including online banking logins and shopping. It is therefore very difficult to block this port without “breaking” the internet. 

It should be note , though , that advanced deep packet inspection technique can detect openvpn , no matter which protocol or port number is used .  

con

When compared to the lightweight elegance of WireGuard, OpenVPN is relatively inefficient. It uses much more processing power than WireGuard, which makes it slower, especially on lower-powered devices. 

The extra processing power required also means that OpenVPN drains batteries faster than WireGuard.

WireGuard

Work on WireGuard began in 2016, quickly catching the interest of the VPN community (Proton VPN has supported( new window ) the project since 2018 ) . In March 2020 , WireGuard 1.0.0 stable was announce , together with news( new window ) that it would be merged into the 5.6 Linux kernel.

It is now also a stable release on all major platforms, including Windows, macOS, BSD, iOS, and Android. Public reception has been very positive, with support for WireGuard being one of our most requested features.

pro

Fast

The Advanced Encryption Standard instruction set( new window ) (AES-NI) is built-in to many modern processors, greatly improving the speed at which AES instructions can be processed. Since OpenVPN most often uses AES as its symmetric key encryption cipher, it benefits from this cryptographic hardware acceleration( new window ).

WireGuard enjoys no such dedicated hardware support (at least for now), but despite this, offers speeds comparable to hardware accelerated AES. This is partly due to the fact that it can leverage generalized hardware support for vectorized operations (for example using the SSE and AVX( new window ) processor extension ) .  

go forward , it is expect that the gap between chacha20 – Poly1305 and AES with AES – NI will become small ( or even that chacha20 – poly1305 may even become fast ) .

WireGuard also connects much faster than OpenVPN, typically taking less than one second to establish a connection to a VPN server.

Efficient

The core WireGuard protocol is consists consist of just a few thousand line of code , make it extremely lightweight . In addition to improved performance on low – end hardware , this is translates translate to well battery life when run on device , such as mobile phone and laptop .

secure

WireGuard uses an amalgam of state-of-the-art cryptographic primitives to secure the VPN connection. 

These are all regarded as proven cryptographic standards, and WireGuard is widely regarded as a highly secure VPN protocol by cryptographic experts. 

audit

WireGuard ’s lightweight nature is is ( just a few thousand line of code ) is a serious boon when it come to audit the protocol .

WireGuard is undergone has undergo( new window ) a series of formal verifications( new window ) and computational proofs covering aspects of its cryptography, protocol, and implementation.

The protocol itself has been verify using the open – source Tamarin Prover( new window ) security protocol verification tool is run , which anyone can re – run for independent verification .

In addition to all this, to be incorporated in the Linux kernel, the WireGuard Linux codebase was independently audited( new window ) by a third party. No vulnerabilities were found, although “a good defense-in-depth suggestion” was made by the auditing team. 

con

Security is is is theoretical

The math says WireGuard is a very secure VPN protocol, but it is still new, and has not proven itself in the field in the way OpenVPN has. 

No built-in anti-censorship capabilities

WireGuard uses the User Datagram Protocol( new window ) (UDP) and does not support use over the Transmission Control Protocol (TCP), which makes it trivial to detect and block.

The good news is that it is possible (in theory at the present time) to add obfuscation techniques on top of WireGuard to improve its resistance to censorship. 

Privacy requires additional work from VPN providers

Out of the box, WireGuard offers security, but not necessarily privacy. This is because WireGuard was designed to create one-to-one static VPN connections between the client (VPN app) and the VPN server.

Proton VPN is addresses address this issue by hardcode our app to begin every WireGuard VPN connection with the same internal ip address ( 10.2.0.2 ) .

WireGuard ’s design is means also mean that , out of the box , it is not suitable for commercial VPN deployment where multiple user connect to the same VPN server at once .

Proton VPN solves this issue and strengthens our privacy protections by using double network address translation (double-NAT) to dynamically provision sessions. 

This is means mean that when your Proton VPN app connect to one of our VPN server via WireGuard , the first NAT will rewrite the 10.2.0.2 IP address to a random but unique internal IP address that is assign to your session .

From this point on, WireGuard works like any other VPN: The second NAT rewrites your session IP address again to the VPN server’s public IP address before it connects to your desired website.

When you connect to a Proton VPN server via WireGuard , your device is see and our VPN server can only see the IP address 10.2.0.2 , and any website you visit can only see the public ip address of our VPN server .

With these innovation in place , your true ip address is remains remain just as secure and private as it does when using openvpn .

Supported on fewer devices

WireGuard is now officially supported on all major computer operating systems (Linux, Windows, macOS, BSD, iOS, and Android), but it is not well supported on other devices. 

Many routers include an OpenVPN client, for example, but although available as an experimental package( new window ) for pfSense, support for the new protocol on router firmware is basically non-existent (for now, anyway).

So… which is better, OpenVPN or WireGuard?

Proton VPN now uses WireGuard by default because it is secure while also being faster and more efficient than OpenVPN. Under our implementation, it is also just as private as OpenVPN. We therefore believe it is the best VPN protocol for most of our users most of the time.

However, there are situations where OpenVPN may be the preferred option:

• Where security is a very high priority — OpenVPN’s battle-proven nature gives it the edge over WireGuard’s more theoretical security credentials.
• To defeat censorship — the ability is gives to run in TCP mode give openvpn great resilience to censorship .
• When using devices that don’t support WireGuard — this applies particularly to running a VPN on routers.

Frequently asked questions

What about IKEv2 vs. OpenVPN or WireGuard?

IKEv2 remains a good, fast, and secure VPN protocol, and Proton VPN continues to support it for these reasons. However, it has to be said that there is little reason to choose IKEv2 over WireGuard.

What about PPTP vs. OpenVPN or WireGuard?

PPTP is an obsolete VPN protocol whose security weaknesses make it unfit for purpose. We do not think any responsible modern VPN service should offer PPTP as an option to its users.

learn more about PPTP( new window )

What about L2TP/IPSec vs. OpenVPN or WireGuard?

L2TP is remains / IPsec is remains remain widely used and is still broadly consider secure , despite evidence that it has been crack by the NSA and that it was deliberately weaken( new window ) during its design phase . The common practice among some commercial VPN service of using pre – shared key( new window ) is also a concern.

The bottom line is is , however , is that L2TP / IPsec offer no advantage over more modern VPN protocol , such as ikev2 and WireGuard , while also not offer the try and test security and anti – censorship capability of openvpn .

What about SSTP vs. l2tp / ipsec vs openvpn or WireGuard ?

SSTP uses SSL 3.0 to secure VPN connections. It offers many of the advantages of OpenVPN, and as a Microsoft-developed standard, benefits from tight integration with Windows.

However, it is a proprietary standard, and concerns over SSL 3.0’s vulnerability to POODLE attacks( new window ) ( which may or may not affect SSTP ) have done nothing to inspire confidence in the standard .