Open a locked file

Someone locked a file or message with a passphrase and sent it to you. Open it here with that passphrase. Nothing is uploaded: everything happens in this page, on your device. Rather not trust a web page? Open it another way.

Drop the locked file here, or

Passphrase, or your private key if the file was locked for a key

Rather not trust this page?

You do not have to. A file locked with Cipherwind uses the open age format, so it opens without this page and without Cipherwind. Pick whichever you trust most.

1. Use a tool that is not ours (best if you do not trust us)

Install the free age program on your computer, then open the file with it. Nothing here is involved.

Install it: Windows winget install FiloSottile.age, Mac brew install age, Debian or Ubuntu sudo apt install age. Other systems and downloads: the age releases page.
A locked file, with a passphrase. It asks for the passphrase (typing is not shown) and writes the unlocked file under the name you give. Use the file's real ending, for example photo.jpg:
```
age --decrypt -o photo.jpg locked-file.age
```
A locked file made for your key. Save your private key (the line that starts with AGE-SECRET-KEY-1) in a text file called key.txt:
```
age --decrypt -i key.txt -o photo.jpg locked-file.age
```
A locked message. Copy everything from -----BEGIN AGE ENCRYPTED FILE----- to -----END AGE ENCRYPTED FILE----- into a file called message.txt, then:
```
age --decrypt message.txt
```

2. Use the Cipherwind app on Android

It does the same job on your phone, with no web page involved: the Cipherwind page has the Google Play link.

3. Check this page, then use it offline

This page is one file. It loads nothing from the internet and sends nothing back; its security policy forbids it, and that is enforced by your browser.

Save the page (Ctrl+S, or Share, then Save, on a phone) as open.html.
Work out the saved file's fingerprint and compare it with the one published on the Cipherwind page (under "Opens without the app"). If they match, it is the page we published and nobody changed it. Windows (PowerShell):
```
Get-FileHash open.html -Algorithm SHA256
```
Mac:
```
shasum -a 256 open.html
```
Linux:
```
sha256sum open.html
```
Turn off Wi-Fi and mobile data, open your saved copy, and unlock the file. With no connection, nothing can leave your device.

Whichever way you open it, the passphrase must come to you by a different route than the file, and an unlocked file is as private as wherever you save it.

How this works and what to check

The file is locked in the open age format (an .age file). This page unlocks it with a key made from your passphrase, using a slow step (scrypt) so a guessed passphrase is costly to try. The result is only ever held in this browser tab.

The page loads no outside code and sends nothing; you can disconnect from the internet before using it, or save the page and open the saved copy.

If the passphrase is wrong, or the file was changed on its way to you, it will not open. Ask the sender for the passphrase again, by a different route than the file.

The same files also open with the free age command-line tool (age --decrypt file.age) and with the Android app.

Very large files need a browser that can save straight to disk (Chrome, Edge); others keep the unlocked file in memory first.