The security corner

Encrypt and decrypt a file with a password

Drop a file in and give a password: you walk away with a strongbox nobody can open without it. Drop a strongbox in, give the password, and you get the original file back, with its name.

Any type of file100 MB per file

Drop a file, or a strongbox to openAny type of file. Nothing will be sent: neither the file nor the password.Choose a file

This file is beyond what this tool does

This tool needs JavaScript to work, and that is precisely because it works ON YOUR DEVICE: without JavaScript, your file would have to be sent to a server. The instructions and the limits of the tool, however, can be read without JavaScript, just below.

How this is built

Your file never leaves your device

This tool works entirely inside your browser. Not one byte of your file is sent anywhere, and nothing is kept once the tab is closed.

Checkable in ten seconds, without taking our word for it:

Open your browser's inspector: the F12 key (or Ctrl+Shift+I, or Cmd+Option+I on a Mac).
Go to the “Network” tab, then clear the list.
Process a file on this page. The list stays empty: no request goes out.
To go further: cut your connection and do it again. The tool still works.

This absence of requests is also checked BY MACHINE before every release: a lock drives a real browser, processes a real file, and refuses to publish if a single byte goes out.

The proof page, step by step and in pictures

Going further

InstructionsHow it works

This tool does not look at the contents of your file: it encrypts bytes. There is therefore no list of formats. It only looks at the first six bytes, to know whether it has a strongbox to open rather than a file to lock.

VerifyThe proof, step by step

The network inspector check, explained one gesture at a time, with screenshots.

The cornerThe security corner

The other tools in this corner of the workshop.

UnderstandHow this is built

The formats actually handled, browser by browser, and what we ruled out.