How to Send Encrypted Files on Mac

July 21, 2023

Sending Encrypted Files

My favourite free app for encrypting files and folders on Mac is Encrypto. However, if there’s one area where Encrypto falls short it’s sending files to other people. You see, for the recipient to be able to decrypt and read Encrypto files they will also need to install the app. That isn’t ideal.

What you really want is for your recipient to be able to decrypt your files using, say, a password, without the need to install anything at all. Even better if they can do that on any device, whether that be a Mac, PC, or even an iPhone or iPad .

The good news is there’s a free app that lets you do exactly that, and it’s called Keka. Keka is a free app that encrypts your files and zips them up into a single compressed folder, making them easy to send and reduces the overall file size in the process.

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How to Use Keka

If you google Keka, it should be the first result that pops up. When you open the website, you’ll likely be drawn to the App Store link.

I would recommend ignoring this link because Keka is not free on the App Store. You have to pay for it. However, if you go back to the website, there is another link, just below the App Store link, which lets you download a free version. I’m not entirely sure of the differences between the paid and free version. I suspect there might not be any, but this free version is perfect for our needs.

Having installed the app in the usual way, when you open it you’ll be presented with the main, albeit small, screen. There are several options here, but essentially you just want to add a password. This will be the password the recipient uses to decrypt and view the files you are sending them. Having added a password I recommend ticking the box to use 256-AES encryption. This will ensure your files are encrypted using a strong level of encryption the app offers.

Having ticked the box, it’s just a matter of dragging and dropping your files over the app. In my video I send a text file but you can send literally anything, within a reasonable size limit. Having added your files you’ll immediately see a warning which appears because you ticked the box to use 256 AES encryption.

The message is basically saying that some Mac and PCs might have trouble decrypting the files using the stronger level of encryption. This is not the case for Apple Silicon Macs running the latest versions of MacOS. Nor is it true of iPhones and iPads, which can all decrypt the files just fine. However, it is true of Windows PCs, which error when trying to decrypt 256-AES encrypted files.

So if you think the person receiving the file might be using a Windows PC or an old Mac, you might want to choose the option to use ‘legacy encryption’. Your file will still be encrypted using a password but it will just be encrypted using Keka’s weaker cipher.

You’ll be prompted to save your new encrypted Zip file and give it a file name. By default it’ll save your new file to the same directory as the original files. At this point you're all done with Keka, you can close the app, and send your files by whatever means suits you best.

Sending your Encrypted FIles

I’ll demonstrate 3 different ways of sending your encrypted file, starting with iMessage.

When the recipient receives the file via iMessage on their Mac, they just need to save it, then double click it. Your recipient will be prompted for the password and, having entered the password, the decrypted files will be extracted from the zip container.

It’s a similar result on iPhone. Your recipient will need to save the encrypted file to their Files app. Tapping on the file, they’ll be prompted for the password, and again the files will be decrypted and extracted from the zip file..

Finally you can also send your encrypted file as an email attachment. It’s worth remembering that whilst the attachment is encrypted, the actual email is not, so don’t be tempted to include the password in the contents of the email. An encrypted chat messaging app like Whatsapp or Signal is a better option for sending your password.

Having sent your file, your recipient just needs to download it and open it. Now, if your recipient is using a Windows PC, if you ticked the box to use strong encryption in Keka, Windows will not natively decrypt the file. Instead it will display a very unhelpful error.

You can either zip the file in Keka using legacy encryption or PC owners will need to install an application such as 7zip, which can decrypt the file just fine.