Privacy notice and terms

Privacy notice

Who is responsible

Melvin Erk, Cothmannstraße 5-7/22, 1120 Vienna, Austria, contact@kaiserbyte.com. The full details are in the imprint.

What KUVRT is

Messages, media and files are encrypted on your device, and only the people in a conversation, on their own devices, can read them. The server holds sealed envelopes until they arrive and deletes them. There are no accounts, email addresses or phone numbers: your identity is a key made on your device, backed by a recovery phrase that only you hold. KUVRT is built so that we cannot read your messages and do not learn your name or your contacts' names.

What the server processes, why, and for how long

• Sealed envelopes and media pieces in transit, with the technical data needed to deliver them, to deliver your messages (Art. 6(1)(b) GDPR). Deleted when fetched, at the latest after 45 days; the record of whether one was delivered is kept at most 45 days longer. When you add a device, the sealed handover between your two devices waits on the server for at most ten minutes; a short code you share instead of your invite link holds that link for ten minutes. Both serve to connect you (Art. 6(1)(b)).
• Your identity record: public keys, the signed list of your devices, prekeys, and the encrypted identity card that only your recovery phrase can open, to make your identity reachable and restorable (Art. 6(1)(b)). Kept while your identity exists. When you delete it, a tombstone stays for good - its public keys, the signed delete statement, the history of its key changes and, for a deletion made by an older version of the app, its last list of devices - so your own devices can check the deletion for themselves.
• The removals a deletion sends to your contacts and your other devices, sealed so that only the server can open their outer layer, to carry out the deletion (Art. 6(1)(b)). Held until delivered, at the latest 45 days.
• The public key log: random identifiers, public keys and device counts, with when each changed and whether an identity was deleted, public and permanent, so that every KUVRT app can verify keys automatically and a substituted key leaves evidence (Art. 6(1)(b) and (f), the interest being tamper-evident verification). It identifies nobody.
• Push notifications, if you turn them on: the notification address your browser issues, handed to your browser maker's push service, which may be outside the EU, with a wake-up that carries no message content (Art. 6(1)(a)). Kept while enabled; an address the push service has stopped accepting is kept, sealed, until your device replaces it or you switch notifications off, so the device knows to make a new one. This address is kept apart from everything else on the server. After a device is removed or the identity deleted, the address is deleted as soon as that reaches the push part of the server, and in any case 60 days after it was last used. Outside the EU your data may be protected less well than here; switching notifications on is your consent to that (Art. 49(1)(a)), and switching them off in the settings withdraws it.
• Access logs: a daily-salted hash of your IP address, the operation, its status and timing, for security and abuse prevention (Art. 6(1)(f)). Seven days; rate-limiting counters live in memory only, are dropped after a day without use and are gone when the server restarts. Totals for running the service - messages posted and delivered, connections and requests, each minute - say nothing about anyone and are kept 30 days, and by the hour for two years.
• App versions: each time the app opens, it tells the server its version number. The server counts the opens of each version per hour, in memory only, with nothing about who or which device opened it, so that we can see an update arrive safely (Art. 6(1)(f), the interest being running updates safely). Kept for 24 hours and gone when the server restarts.
• Messages you send us with "Write to us": the text, a picture if you add one, and the technical details if you leave them on. They are stored without your identity, so we can look into the problems you report (Art. 6(1)(f), the interest being fixing what goes wrong). Deleted after 90 days at the latest.
• Email you send us at contact@kaiserbyte.com - a question, a report or a request about your rights - and our answer, so that we can reply and deal with it (Art. 6(1)(c) and (f), the interest being answering you). Kept as long as the matter and our legal duties need.
• Tips: Stripe Payments Europe, Limited, Ireland, processes the payment on its own page, under its own notice, and sends you a receipt. We receive the amount, the email address you gave Stripe and the payment details Stripe shows a seller, such as the type of card, its last digits and its country, and keep them for seven years (Art. 6(1)(c), § 132 BAO). Not tipping shares nothing.

Cookies and tracking

The app sets one cookie, kuvrt_had, once this browser holds a KUVRT. It holds only the value 1 - nothing about you, your identity or your device - goes back only to kuvrt.com/had and never to the server that carries messages, is not logged, lasts 400 days and is removed whenever you erase KUVRT in the app. It lets KUVRT tell you that the browser deleted its data, instead of greeting you as someone new. No tracking, no analytics service, no automatic crash reporting, no third-party scripts, fonts or images; the count of app versions and the totals above are the only counts of how KUVRT is used. Technical details leave your device only when you copy them yourself or send them to us with "Write to us".

Recipients

Hetzner Online GmbH, Gunzenhausen, Germany, hosts the server under a data processing agreement. Email reaches our mail provider in the EU. Notifications reach your browser maker's push service, tips reach Stripe.

Your rights

Access, rectification, erasure, restriction, portability and objection. Erasure and portability are self-service in the app: delete your identity, export your data. The complaint authority is the Austrian Datenschutzbehörde, Barichgasse 40-42, 1030 Vienna.

Changes

This page carries a version and a date at the top. Material changes are pointed out in the app.

Terms

• KUVRT is free and provided as is. There is no warranty of any kind, and no promise that it is available, that a message arrives, or that anything is kept.
• Any part of it may be changed, paused or stopped at any time, with a notice in the app where that is possible.
• Limits on size, rate and volume apply and may change, and traffic that harms the service or the people using it may be limited or blocked.
• We can neither read nor moderate what people send, so nothing is filtered, reviewed, ranked or decided about automatically. To report illegal content, write to contact@kaiserbyte.com and describe what happened; a screenshot helps. We cannot read anybody's chats, so we act on what you send us. Blocking the sender stops everything from them at once.
• You are responsible for what you send, for what you use KUVRT for, and for keeping your recovery phrase. Use KUVRT only in ways that are lawful where you are and under Austrian law.
• KUVRT is for people aged 16 and over.
• Your device is the boundary: whoever holds your recovery phrase is you, and anything on an unlocked device can be read. KUVRT is delivered by our server every time you open it, so what runs in your browser depends on that server. The network can see when a device talks to KUVRT and how much, never what is written. Our server can also tell which of the random identities it holds exchange messages, and when - never what is written. It holds no names, phone numbers or email addresses for them.
• Nothing you lose can be restored: your messages exist on your own devices and nowhere else.
• We are liable for intent and gross negligence, and for personal injury. Liability for slight negligence is excluded.
• Austrian law applies. If you use KUVRT as a consumer, you keep the protection that the mandatory law of the country where you live gives you, and you can go to its courts. Creating an identity means accepting these terms; if you no longer agree, you can delete your identity at any time.