We have a new series of articles on our blog, written by our engineers and developers. It's meant to provide insight into our work processes, to make them more transparent and to satisfy the curiosity of our community’s tech-savvy members.

The series started with our post about the migration from polyrepo to monorepo architecture (https://www.reddit.com/r/ProtonMail/comments/yxr419/a_closer_look_into_the_technical_challenges_of/ ). Now, we’d like to tackle a tricky one - email content search.

Cryptography is, as you know, at the heart of all our services. But occasionally, it hinders basic functionalities that everybody is accustomed with non-privacy-focused services. Email content search is perhaps the most obvious one, and likely the biggest pain point for a number of our users.

With encrypted search available on our web app and in works on Proton mobile apps, we decided to share a detailed account of the hard problem at the core of this functionality, and our approach to solving it: https://proton.me/blog/engineering-message-content-search.

Does this problem remind you of an equivalent challenge from your line of work - a situation in which one benefit offsets the other? If yes, let us know in the comments below.