WireGuard is a communication protocol and free and open-source software that implements encrypted virtual private networks (VPNs), and was designed with the goals of ease of use, high speed performance, and low attack surface. It aims for better performance and more power than IPsec and OpenVPN, two common tunneling protocols. The WireGuard protocol passes traffic over UDP.
In March 2020, the Linux version of the software reached a stable production release and was incorporated into the Linux 5.6 kernel, and backported to earlier Linux kernels in some Linux distributions. The Linux kernel components are licensed under the GNU General Public License (GPL) version 2; other implementations are under GPLv2 or other free/open-source licenses.
The name WireGuard is a registered trademark of Jason A. Donenfeld.
Protocol
WireGuard uses the following: Curve25519 for key exchange ChaCha20 for symmetric encryption Poly1305 for message authentication codes SipHash24 for hashtable keys BLAKE2s for cryptographic hash function HKDF for key derivation function UDP-based only
In May 2019, researchers from INRIA published a machine-checked proof of the WireGuard protocol, produced using the CryptoVerif proof assistant.
Optional Pre-shared Symmetric Key Mode
WireGuard supports pre-shared symmetric key mode, which provides an additional layer of symmetric encryption to mitigate future advances in quantum computing. This addresses the risk that traffic may be stored until quantum computers are capable of breaking Curve25519, at which point traffic could be decrypted. Pre-shared keys are "usually troublesome from a key management perspective and might be more likely stolen", but in the shorter term, if the symmetric key is compromised, the Curve25519 keys still provide more than sufficient protection.
Networking
WireGuard uses only UDP, due to the potential disadvantages of TCP-over-TCP. Tunneling TCP over a TCP-based connection is known as "TCP-over-TCP", and doing so can induce a dramatic loss in transmission performance (a problem known as "TCP meltdown"). TCP meltdown occurs when a TCP connection is stacked on top of another. The underlying layer may detect a problem and attempt to compensate, and the layer above it then overcompensates because of that, and this overcompensation causes said delays and degraded transmission performance.
WireGuard fully supports IPv6, both inside and outside of tunnel. It supports only layer 3 for both IPv4 and IPv6 and can encapsulate v4-in-v6 and vice versa.
Extensibility
WireGuard is designed to be extended by third-party programmes and scripts. This has been used to augment WireGuard with various features including more user-friendly management interfaces (including easier setting up of keys), logging, dynamic firewall updates, dynamic IP assignment, and LDAP integration.
Excluding such complex features from the minimal core codebase improves its stability and security. For ensuring security, WireGuard restricts the options for implementing cryptographic controls, limits the choices for key exchange processes, and maps algorithms to a small subset of modern cryptographic primitives. If a flaw is found in any of the primitives, a new version can be released that resolves the issue.
Reception
A review by Ars Technica found that WireGuard was easy to set up and use, used strong ciphers, and had a minimal codebase that provided for a small attack surface.
WireGuard has received funding from the Open Technology Fund. and donations from Mullvad, Private Internet Access, IVPN, the NLnet Foundation and OVPN.
Oregon senator Ron Wyden has recommended to the National Institute of Standards and Technology (NIST) that they evaluate WireGuard as a replacement for existing technologies.
Availability
Implementations
Implementations of the WireGuard protocol include: Donenfeld's initial implementation, written in C and Go. Cloudflare's BoringTun, a user space implementation written in Rust. Matt Dunwoodie's implementation for OpenBSD, written in C. Ryota Ozaki's wg(4) implementation, for NetBSD, is written in C. The FreeBSD implementation is written in C and shares most of the data path with the OpenBSD implementation. Native Windows kernel implementation named "wireguard-nt", since August 2021.
History
Early snapshots of the code base exist from 30 June 2016. Four early adopters of WireGuard were the VPN service providers Mullvad, AzireVPN, IVPN and cryptostorm.
On 9 December 2019, David Miller – primary maintainer of the Linux networking stack – accepted the WireGuard patches into the "net-next" maintainer tree, for inclusion in an upcoming kernel.