With Proton Calendar, all of an event’s critical information, like the title, description, location, and attendees, are stored securely and privately with end-to-end encryption. Not even Proton can read your event details.
Elliptic curve cryptography
Proton Calendar leverages advanced, high-performance elliptic curve cryptography (ECC Curve25519) to secure your data. This happens automatically in the background without requiring any action from you.
Open source and independently audited
The Proton Calendar web app is fully open source, so the code is available for inspection. Our mobile apps' code will be open sourced next. Our apps have been independently audited to verify that they actually work as advertised.
It is possible to invite other people onto a shared Proton Calendar. We utilize a secure invitation protocol that cryptographically certifies that the person inviting you is who they say. If you send the invitation, it also lets the invited member cryptographically verify that it was you who invited them.
The signature of the data cryptographically ensures that each type of data was created and edited by the specified author and guarantees that nobody (not even Proton) has tampered with your events.
This cryptographic verification happens automatically in the background without requiring any action from you.