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Encrypt text with a password

A message in a chat stays with the messenger for ever. Encrypt it here instead: you get one line that can be pasted into any chat or email and read only with the password. Encryption and decryption happen in your browser, we see neither the text nor the password.

Pass the password to the recipient some other way, not the one the line itself travels by.

Neither the text nor the password goes anywhere: the page computes everything inside the tab and makes no network requests.

What the recipient sees

They get a line like 404T1.iVBORw0KGgo… and the password through another channel. They open this same page, switch to "Decrypt", paste the line and the password. Nothing else is needed: no sign-up, no program, no extension.

The line can be pasted anywhere, a chat, an email, a comment, a file description. It contains no spaces or line breaks, so neither messengers nor mail clients spoil it.

What is not protected here

The contents are hidden, but not the fact of the conversation. Who sent an encrypted line to whom and when is still visible, and no cipher changes that. Second: the password. If it travels by the same channel as the line, the point is lost, the whole idea rests on the fact that usually only one of the two is intercepted.

Nearby: encrypt a file, a note that burns after reading and a password generator.

The contents are closed; the road remains

Whom you write to and when is visible even without the contents. 404 VPN closes that part, and we keep no visit logs.

How it works →

FAQ

guest@404vpn:~$ cat text-crypt-faq.md
[01] $ Why one long line instead of a block with a frame? ▸
> Because a block falls apart when forwarded. Messengers wrap lines, mail clients add indents, forums collapse spaces, and the ciphertext stops decrypting while still looking intact. One line with no spaces survives all of that and pastes anywhere.
[02] $ How is this different from encrypting a file? ▸
> Only in convenience: the crypto is the same, AES-256-GCM with a key derived from the password through a million PBKDF2 rounds. A file is handy for passing a document, a line for a couple of sentences right inside a chat, without making the recipient download anything.
[03] $ What can someone who intercepts the conversation see? ▸
> That you sent an encrypted line, how long it was and roughly when. The contents, no. Encryption cannot hide the fact of the conversation: for that you need a different channel, not a different cipher.
[04] $ Can someone decrypt a line without the password? ▸
> No. Brute force is the only way, and it runs into the length of the password: key stretching makes every attempt expensive. A short dictionary password will be found; three or four unrelated words, practically not.
[05] $ Do you store the text or the password? ▸
> No. The page makes not a single network request while encrypting or decrypting, WebCrypto does it all inside the tab. You can check in the Network tab of the developer tools: pressing the button makes nothing appear there.