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A note that burns

A password sent through a messenger stays there for ever — in the history, in the backup, in the recipient’s cloud. Write it here instead: the text is encrypted right in your browser, you get a link, and after the first read the note is gone. The key lives in the link itself and never reaches our server.

Send the link to the recipient. It can be opened once.

Ready to write

What exactly we hold

A string we cannot read, and its name. The text is encrypted in your browser with AES-GCM, and the key is placed in the part of the link after the hash — by the design of the protocol that part is never sent to a server at all, only the browser sees it. The note’s name is a hash of the same secret, so nothing can be recovered from it either.

What it protects against: the secret does not stay in the correspondence for ever, does not end up in backups and does not resurface a year later in the chat history. What it does not protect against: someone who intercepted the link before the recipient. Even that you will notice, though — the recipient gets an already burned note.

Nearby: encrypt a file with a password, if the secret is not text, and a password generator.

The same principle in everything else

404 VPN keeps no visit logs, no DNS queries and no traffic contents. Not because we promise, but because there is nothing to hand over on request.

How it works →

FAQ

guest@404vpn:~$ cat note-faq.md
[01] $ Can you read my note? ▸
> No. The text is encrypted in your browser, and the key stays in the part of the link after the hash — browsers never send that part to a server, that is how the protocol is built. What we hold is a string and its name, which is itself derived from the key by hashing. We have nothing to decrypt it with.
[02] $ What if the wrong person opens the link? ▸
> Then they read the note — and the real recipient sees that it has already burned. There is some use in that: you find out at once that the link went astray. But a note protects you not from an intercepted link, it protects you from a secret living in a chat for ever.
[03] $ Why does the note not burn when a messenger shows a preview? ▸
> Because following the link does not burn it. Messengers and mail clients fetch addresses themselves to draw a card — if reading happened on arrival, the note would vanish before the recipient. So arriving only asks whether it exists; pressing the button burns it.
[04] $ How long does a note live if nobody opens it? ▸
> As long as you chose: an hour, a day or a week. When the term ends it is wiped from our disk, even if it was never read. We keep no copies and no backups.
[05] $ How is this different from disappearing messages in a messenger? ▸
> It does not require both sides to use the same messenger, and the secret never passes through the chat at all: what stays in the chat is only a link with nothing behind it any more. And you can send the link through one channel and mention it through another.