Hands-on: MiniLock’s powerful file encryption is dead simple to use

THE CREATOR OF Cryptocat, Nadim Kobeissi, is back with another easy-to-use encryption tool. This time it’s a free Chrome app called miniLock fao.pcworld.com/minilockl that aims to make it easy to create and share single encrypted files with others.

Similar to other encryption tools, miniLock relies on public-key cryptography. Under this scheme you have to share your public key with others so that they can encrypt files meant for you and only you.

But unlike many encryption tools, miniLock is very easy to understand and use.

The public key itself, dubbed your miniLock ID, is relatively short at around 45 characters. But it’s still too long to remember easily, so you’ll want to write it down or save it in a password manager such as LastPass or KeePass.

Implementation is key

The encryption scheme that miniLock employs is Curve25519 elliptic-curve cryptography, which is the same type of cryptography that Cryptocat uses. However, the problem with encryption tools often isn’t the strength of their encryption but how well the encryption is implemented.

Judging the quality of the cryptography is beyond the scope of this article. But on the miniLock site (minilock.iol.you can find a recent miniLock security audit by penetration-testing firm Cure53. The report gave miniLock a clean bill of health.

For anyone who wants to dive in right away, here’s a quick hands-on tour of miniLock on a Windows 8.1 PC.

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Generating your ID

To get started, visit the Chrome Web Store (ao.pcworld.com/ minilockappland install miniLock as you would any other Chrome app. Then you can either launch it right from the Chrome Web Store or via the Chrome App Launcher (go.pcworld.com/chromeapplaunchl in yourtaskbar, if you’ve installed that.

When it starts up, miniLock will ask you to sign in with your email address and a passphrase. The app will use these two pieces of information to generate your miniLock ID, which should take only a second or two.

In my tests, miniLock was fairly picky about passphrases. I tried using a ten-character randomly generated passphrase with capital and lowercase letters, numbers, and special characters. That should make for a fairly solid password if you ask me—but for miniLock it wasn’t strong enough.

Instead, the app suggested that I use one of its auto-generated passphrases, which consist of a series of random dictionary words. To make things easier, I used one of the passphrases generated by miniLock, but you could also write your own. Just make sure it’s unique and memorable enough that you won’t forget it. Otherwise, storing it in a password manager will be important. As with other encryption tools, if you lose that passphrase, you won’t be able to unlock any files sent to you with that miniLock ID.

Now that you have your own ID set up, let’s encrypt a file to see how it works. Make sure you back up the test file in unencrypted form just in case something goes wrong.

To choose a file, either tap the file-drop area in the miniLock window or drag a file from File Explorer and drop it in the miniLock window. You’ll then see the miniLock window flip around and reveal space for entering up to four miniLock IDs.

By default, your miniLock ID will appear at the top, as you are the person encrypting the file.

Below that, you have the option to add another three people you want to be able to access the encrypted the file—assuming you have their miniLock ID. If you wanted to send this file to one person and didn’t want to have access to it yourself, you could just click the X to the far right of your miniLock ID to remove your key.

You also have an option underneath the filename to have miniLock create a random filename something you might do if you want to be really secretive about what you’re sending.

Once the IDs for every recipient are ready to go, tap the arrow at the bottom of the window to start the encryption process. Depending on the size of the file, it could take a few seconds ora few minutes to finish.

After the encryption is done, the app will tell you “Your encrypted file is ready” in small letters below the filename. Next, click on the filename to save the file to your PC via Chrome’s downloads manager.

Now that you have an encrypted file, you can send it to the intended recipients any way you like: email, instant message, USB key,

Facebook—the choices are seemingly endless.


Decrypting a file is even easier than encrypting. Once you receive your miniLock-encrypted file via email (or whatever method), download it to your PC and drop it into the miniLock window. As long as you are signed in to miniLock and the file is encrypted with your miniLock ID, the file will be automatically decrypted. Then you can save it to your PC the same way you did with the encrypted file.

That’s about all there is to miniLock. The only drawback that some people might find is that you have to sign-in every time you open the app. MiniLock does not save your login across user sessions. That was likely a conscious choice to protect your privacy. Still, some people may find the constant logins to be a drawback.

7Review earns Amazon affiliate commissions from qualifying purchases. You can support the site directly via Paypal donations ☕. Thank you!
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