Security

How we protect your data

Meetarium is end-to-end encrypted: everything you enter is encrypted in your browser before it reaches our server. The server only stores ciphertext – and has no key for it.

1. The link is the key

When you create a poll, your browser generates a random secret (256 bits). It is in the link after the # sign. Browsers never send this part of an address to servers – it does not appear in any server log.

The browser derives everything else from the secret using HKDF-SHA-256. The invitation link is itself derived – the organiser link cannot be computed back from it.

What our server sees

  • a random identifier per poll
  • hashes of the access tokens
  • when something changed and how many records there are
  • the size of the records (padded to fixed blocks)

What it does not see

  • title, place and description
  • the suggested dates
  • names and answers of participants
  • comments and the chosen date
  • the keys themselves

2. Three kinds of links – roles without accounts

🔑Organiser linkchange suggestions, fix the date, remove answers, delete the poll – just for you
✉️Invitation linksee the dates and enter your own answer – for everyone invited; does not reveal the organiser link
✍️Edit linkchange your own answer on another device – just for you

3. Signed answers

Everyone invited has the same content key – so anyone could encrypt anything. That is why every change is also digitally signed: settings and suggestions with the organiser's key, each answer with its own key that the browser creates when it is first saved. Every person's browser checks all signatures. Other people's answers can neither be changed nor forged – not even by the server.

4. Check your calendar without handing it over

With “Check calendar” your browser reads a calendar file (.ics) from your device and suggests “no” for clashing dates. The file is not uploaded, not stored and never leaves your device. Only what you tick yourself in the end is transmitted.

5. Honest limits

Anyone with the invitation link sees all answers. As with any scheduling poll. Share it only with the people who are invited.
Organiser link lost = organising over. We cannot recover any key. The poll stays readable, but fixing the date and deleting only work with the organiser link.
You trust the program code. As with any encryption in the browser, the code comes from our server. A compromised server could deliver manipulated code. We use strict security rules (CSP), load no third-party scripts and publish the source code.
Metadata remains visible. The server sees when and how often a poll is used – but not what it contains.

Technology in brief

  • AES-256-GCM – encryption of every record, bound to poll, type and identifier
  • HKDF-SHA-256 – derivation of all keys from the secret in the link
  • ECDSA P-256 – signatures for settings and every single answer
  • Web Crypto API – the browser's built-in cryptography, no third-party library

Same result on every device: changes are encrypted individually and merged in the browser (“last change wins” per field). Gaps or a rolled-back state are noticed.

Create poll → Privacy policy