Productivity6 min read•
End-to-end encrypted calendar: why your schedule is more revealing than your files
A calendar exposes who you meet, when, where and how often. Here is what an encrypted calendar must protect, what metadata usually leaks, and how invitations still work.
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Three private surfaces. Same zero-knowledge architecture.
Your calendar is a map of your life Files sit still; calendars move. A year of entries reveals your employer, your clients, your doctors, your lawyer, your travel, your relationships and your negotiations. Yet calendars are usually the last thing anyone encrypts, because invitations are assumed to require a readable server.
What an encrypted calendar must actually protect - **Titles and descriptions** — the obvious part. - **Participants** — often stored in the clear even when the body is encrypted. - **Locations and attachments** — meeting rooms, addresses, agendas. - **Timing patterns** — the fact that you meet the same party weekly is itself sensitive.
How DRIVUNO approaches it Events are encrypted on your device with XChaCha20-Poly1305. Each event's key is sealed for every participant with X25519, so a shared meeting is readable by exactly the people invited. The server stores ciphertext, sealed key envelopes and the minimum scheduling structure required to deliver reminders.
Searching your own calendar works through blind indexes: your device computes HMAC tags for words in titles and participants, the server matches opaque tags, and your browser decrypts the matches.
Invitations across systems An invitation to someone outside your vault cannot be end-to-end encrypted, because their provider must read it to display it. The honest design is to make that boundary explicit: internal invitations stay sealed, external ones carry only what you choose to disclose.
Reminders without disclosure Notifications are generated from the encrypted event on your own devices. A push payload does not need to include a subject line to wake up an app that can decrypt it locally.
Why this pairs with encrypted mail and Rooms Meeting notes end up in documents, the agenda arrives by email, the debrief happens in a chat channel. Encrypting one and not the others just relocates the exposure. A single vault with one key hierarchy keeps the whole workflow — mail, calendar, documents, messaging, tasks — under the same guarantee.
Start free and put your schedule behind the same architecture as your files.
Try it in one click.
Three private surfaces. Same zero-knowledge architecture.