Proton
protonmail-openpgpjs-protonmail-security-audit

Proton Mail’s open-source encryption library, OpenPGPjs, has passed an independent security audit

At Proton Mail, our goal is to make encryption as widespread and accessible as possible. We believe a key step toward that is having well-maintained, robust, and secure open source encryption libraries(new window). This is the goal of our efforts on the OpenPGPjs encryption(new window) library, which is today used by hundreds of applications (including Proton Mail) serving millions around the world. As the maintainer of OpenPGPjs, we are responsible for making sure the library is up to date and secure, as well as offering basic support to developers who wish to use it.

In March 2018, we released Version 3.0 of OpenPGPjs(new window). With this major update, OpenPGPjs is even more powerful, secure, and efficient. As part of this update, the OpenPGPjs developer community commissioned an independent security audit from the well-respected security firm Cure53(new window). Independent security audits are an important way to ensure there are no vulnerabilities that could be exploited by attackers.

Summer 2018 Security Audit Coverage

The version 3.0 release brought many new features and improvements, such as support for elliptic curve cryptography(new window) (ECC), which uses smaller signing and encryption keys compared with RSA cryptography(new window) (what Proton Mail uses now), making it a faster and more efficient alternative.

The new version also adds compression, which reduces the size of data before encryption to save space (and time) during encryption and transmission. OpenPGPjs now also offers support for AEAD(new window) (Authenticated Encryption with Associated Data). This protocol provides confidentiality, integrity, and authenticity guarantees on encrypted data, so that when you decrypt data, you can be sure this was the exact same data encrypted by your sender, and you can be sure that it was indeed encrypted by that sender. For those who are interested, you can find the full technical details of OpenPGPjs Version 3.0 here(new window).

The Cure53 team focused on a couple of these new features while also taking a closer look at some key aspects of OpenPGPjs’ crypto implementations. In particular, the audit focused on the following:

  • AEAD encrypted packets
  • EAX, GCM, OCB
  • CMAC
  • All cryptographic primitive implementations: AES, AES-EAX, AES-GCM, AES-CBC, ED25519, C25519, ECDSA, HMAC, P256, P384, P521, SECP256K1
  • Prime number handling
  • Date support in signatures
  • Cryptographic API exposure via different providers

OpenPGPjs Audit Results

We are pleased to receive a highly positive result from the audit. No major issues were discovered. In their summary, Cure53 provided the following feedback(new window):

“Tested cryptographic implementations were top notch and excellent quality given the platform. The only limitations come from the platform itself (JavaScript/web), which do not allow for side channel resistance or reliable constant time operations. Overall however this is an exceptional library for JavaScript cryptography.”

As OpenPGPjs forms the foundation of Proton Mail’s encryption, this result provides extra certainty that Proton Mail’s cryptography is properly protecting users as intended. Working with the open source community is an important part of what we do at Proton Mail, and we will continue to build out the OpenPGPjs library. We are grateful to the Proton community for supporting us in these efforts.

Sign up and get a free secure email account from Proton Mail.

We also provide a free VPN service(new window) to protect your privacy.

Proton Mail and Proton VPN are funded by community contributions. If you would like to support our development efforts, you can upgrade to a paid plan or donate. Thank you for your support!

Related articles

An illustration of a laptop with chains and a padlock on the screen to represent a ransomware attack
A ransomware attack is a serious threat for an organization. Here's what they are, how to avoid them, and 11 of the most well-known incidents.
Is Google Calendar private
This article explores what’s at stake when you use Google Calendar, and how using Proton Calendar gives you control over your data.
The cover image for a blog advertising the new Proton Pass switch campaign
Switch from your current password manager to Proton Pass and we’ll pay for the remainder of your contract. Learn how to switch.
An image showing Proton Drive's open-source code in GitHub
Proton Drive’s desktop apps are open source, meaning you can review the code of any Proton Drive app for yourself.
how to create a business email account
This article explains how to create a business email account that’s secure by default using Proton Mail.
A cover image for a Proton blog about how to safely share your wifi password - image shows a wifi symbol with a button saying 'share' with a key symbol
Is it safe to share Wi-Fi passwords in a text? Here’s how to share your Wi-Fi password easily and securely on any device, from any location.