We’re happy to announce that the Proton Mail iOS app is now fully open source.
We believe in transparency, the power of community, and building a more private and secure future for all. That’s why our web app has been open source since 2015(neues Fenster), and it’s why we have contributed to the open source community by maintaining cryptographic libraries for the JavaScript(neues Fenster) and Go(neues Fenster) programming languages.
Now we’re taking the next step by open sourcing our iOS app. You can find the code on our Github page(neues Fenster).
Why open source?
At Proton, security is our overriding priority, particularly because of the many dissidents and activists who use our service(neues Fenster). Our emphasis on security extends to all areas of our work, from our use of end-to-end encryption(neues Fenster), to the way we engineer our applications. As part of our commitment to security, we are putting all of our software through rigorous, independent third-party audits.
Already there are third-party audits for OpenPGPjs(neues Fenster) and GopenPGP(neues Fenster), our open source cryptographic libraries. Earlier this year, we engaged the renowned security firm SEC Consult(neues Fenster) to conduct an independent audit of Proton Mail’s iOS application. We are now making our iOS app open source now that it has been independently vetted. For more information, read the full iOS app audit report(neues Fenster).
Open source provides transparency and accountability to the Proton community. Allowing people to see and review our code increases trust in both the security of the platform and our commitment to develop a more secure and private Internet. By making our code available to the world, and with the help of our bug bounty program(neues Fenster), we can leverage the global Proton community to make our software as secure as possible.
Open source at Proton Mail
We strongly believe in open source, and we are committed to open sourcing all of our client software. Our web app has been open source(neues Fenster) since 2015, and since we made our iOS app open source, we have published the code for our desktop Bridge app(neues Fenster), our Android app(neues Fenster), and all the Proton VPN apps(neues Fenster).
This means that all Proton apps that are out of beta are open source.
In addition to making our iOS app open source, we have also documented and published our iOS security model(neues Fenster). This is important to us because raw code without documentation can be almost unintelligible sometimes, and a documented security model will assist in rigorous assessment and review of our code by the public. Our iOS trust model(neues Fenster) is also available on our Github page.
There has been a recent increase in state-sponsored malware attacking iOS, and in some cases specifically targeting Proton Mail users. Our iOS security model also highlights exactly what we are doing to give Proton users a higher level of security compared to typical apps. In particular, we have implemented safeguards which allowed the Proton Mail iOS app to protect against a recent malware targeting Tibetans and Uyghurs (see our security advisory(neues Fenster)).
Making our code freely accessible to the developer community also encourages innovation in the field of privacy tech. Developers are free to implement and build upon the methods that we have documented and published. We believe that when developers work together to solve real-world privacy challenges, everyone benefits, and we hope that the publication of our code will result in safer and more robust iOS apps.
We’re excited to share our code, and we look forward to hearing your feedback on Github or directly via email at [email protected].
Best Regards,
The Proton Mail Team
You can get a free secure email account(neues Fenster) from Proton Mail here.
We also provide a free VPN service(neues Fenster) 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(neues Fenster). Thank you for your support.
