Applied Cryptography Engineer

Job description

A better internet, where privacy is the default, is possible. Building this better internet might seem daunting or even unthinkable, but at Proton, this is what we do every day.
Proton was founded in 2014 by a group of scientists who met at the European Organization for Nuclear Research (CERN). Our first product, Proton Mail, is now the world’s largest encrypted email service. Subsequent Proton products, such as Proton VPN, Proton Calendar, and Proton Drive, give our users full control over how and with whom their data is shared.
Today, Proton makes privacy universally accessible. Journalists from outlets like The Guardian and The New York Times, some of the world’s largest organizations, and people in more than 180 countries have signed up for over 70 million accounts. Our diverse and dynamic team is made up of more than 400 members representing over 40 different nationalities. While we are based in Geneva, Switzerland, we have offices in Zurich, Prague, London, Vilnius, Skopje, Taipei, and many more employees working remotely around the world.
Join one of Europe’s fastest-growing companies to help us solve challenging problems and build new products that will reach hundreds of millions of people. We want to create more than just one of the world’s most impactful tech companies; we want to create a new internet that serves the interests of all people. We need you, your voice, your ideas, and your ambition to make it happen.

Purpose of the role

At ProtonMail, we have prioritized the research and development better cryptographic tools and processes. We currently maintain OpenPGP.js, the world's most widely used JavaScript cryptography library, as well as a cryptography library written in Go that is used by our mobile and desktop applications. In addition to maintaining and expanding these libraries, ongoing cryptography-related projects include building a key verification system, source code verification, and preparing for post-quantum crypto. All this work is meant to be compatible with and contribute to the wider OpenPGP community.


What you will do

  • Maintain and add new features to our cryptography libraries
  • Ensure that the libraries and our usage of cryptography are secure
  • Help integrate the cryptography libraries into our products
  • Write high quality, tested, and documented code
  • Follow and improve high engineering standards and best practices

Job requirements

  • Strong background in computer science (algorithms, data structure, software design, reliability, maintainability, etc)
  • Knowledge of JavaScript and/or Go (the two languages in which our cryptography libraries are written)
  • Strong English communication skills
  • Experience with secure application development, a good understanding of security best practices, and a keen eye for potential vulnerabilities
  • High-level knowledge of cryptographic building blocks, including what they guarantee and when and how to use them

Bonus points for:

  • Low-level knowledge of crypto primitives, how they work, and how to securely implement them
  • Experience developing crypto libraries
  • Experience with Rust
  • Experience reading, implementing and perhaps even writing RFC-style specifications
  • B.S. and/or M.S. in Computer Science or Mathematics (or equivalent)

Why you should join Proton
  • Be part of a movement - Proton is not just a product or service but a community-driven movement united by a shared vision of online freedom. Our services are open source, audited, and supported by community contributions. We give back to our community by maintaining core encryption libraries and supporting organizations that advance the same goals as us. Proton is free, open source, neutral, independent, and community first, while remaining financially sustainable.
  • Work with smart and dedicated people - Our team is diverse, collaborative, and tight-knit, with people coming from all walks of life. Many members of our team spent time at the world’s top academic institutions, including MIT, Harvard, Stanford, Princeton, Caltech, Cambridge, and ETH.
  • Join a strong brand - Our encrypted email service – Proton Mail - has grown to be a staple of online security and privacy. Proton has been featured in multiple popular television and film productions, such as Mr. Robot, Knives Out, Sounds of Metal, and more.
  • Grow with us - We’re one of Europe’s fastest-growing companies. Our growth gives you limitless career and educational opportunities as well as the opportunity to work side-by-side with many world-leading experts in their fields.
  • Have your voice heard - We value your opinion and encourage you to speak up and share your ideas and thoughts. At Proton, no problem is someone else’s problem. We collectively strive to do the right thing and be the undisputed best in the world at everything we do.
  • Benefits – these vary by location and type of contract but expect support on your vacation, parental leave, refreshment if working from the office, learning and development opportunities, equity for shared success, flexible working hours and remote work, company events, and team-building activities.


Proton uses the Recruitee recruitment platform for a more effective hiring process and a better candidate experience. Your data will always be kept confidential and is not shared with any third parties. You will receive emails from the email address careers@protonmail.recruitee.com or other addresses on the protonmail.recruitee.com domain as part of the recruitment process.

Proton does not accept unsolicited resumes from any sources other than directly from a candidate. Proton will not pay a fee for any placement resulting from the receipt of an unsolicited offer, even in a situation where Proton employs the relevant candidate. 
By applying to a role at Proton, you acknowledge that we will process and store your personal data for at least the duration of the hiring process and as necessary to enter a contractual relationship with you.