Two free ways to encrypt Google Drive files

This month marks the sixth anniversary of my Google Drive account. I've been aware since the beginning that the thousands of files I have uploaded to the service are stored unencrypted on Google's servers.

That hasn't prevented me from uploading plenty of sensitive information to Google Drive, including dozens of invoices that list my address and the amount of money I was billing for, although the invoices do not include any bank-account or Social Security numbers.

I could have easily encrypted the files using any number of free services. In last May's "Free services make Gmail, Google Drive, and Google search more private," I described the BoxCryptor program that adds an encrypted folder to Google Drive.

I recently discovered two free services that take different approaches to online encryption. With Fogpad, you create and edit text files via a basic online word processor. The files are encrypted on the client PC before being uploaded automatically to your Google Drive account.

Update on August 4, 2013: The Fogpad site was unavailable for several hours today, but as of 9:30 p.m. PDT the service is back online.

By contrast, the Tresorit cloud-storage service lets you download some or all of your Google Drive files, then encrypt them in the Windows-based Tresorit program as they are uploaded to your Tresorit account in the cloud. Tresorit offers 5GB of free online storage, and the company plans to release versions of the program for Macs and iOS devices.

Fogpad is the simpler of the two methods, but it encrypts text files only and requires that you create the file on the Fogpad.net site. Tresorit lets you transmit an encrypted version of the files stored in a folder on your Windows PC to the company's servers.

Both services encrypt the files on the client side, so the companies themselves are unable to decrypt the files you store on their servers. That doesn't guarantee the security of the data, however.

Last week, CNET's Declan McCullagh explained revelations by the Foreign Intelligence Surveillance Court in proceedings relating to requests by Microsoft and Google to disclose details about their interactions with government agencies.

It would appear that if data exists anywhere on the Internet, the U.S. government may request access to it, although major Internet service providers insist they do not honor every data request a government agency makes. The rule remains: If it's really sensitive, it doesn't belong anywhere online.

Password-protect the text files you store on Google Drive
When you click the big, red "Create a secure document" button on the main Fogpad page, you're prompted to sign into your Google account. The first time you do so, you're asked to grant the service access to your account.

You're then prompted to enter and confirm a password for the document.

Type your password twice and press Enter to open the Fogpad editing window. Click the title at the top of the window to give the file a name. It is saved automatically when you stop typing.

The text-editing options include the standard cut, copy, paste, find, replace, and format text. You can insert images, tables, lines, and special characters. Apply one of 15 formatting styles and 10 paragraph formats, including six levels of headings.

When you press the Back button you return to the main Google Drive window. The file name appears in the list, and the file type is labeled "undefined." No preview of the file appears when you select it.

Click Open > Fogpad and enter the file's password to open it in the Fogpad editor. In my testing, encrypted files wouldn't download, and when I shared a link to an encrypted file, the recipient was unable to open the file.

The Fogpad site's About page describes its 256-bit AES encryption as "military-grade cryptography" but offers no other details about the service's encryption methodology.

Transfer encrypted versions of your Google Drive files to another service
Where Fogpad encrypts Google Drive files one at a time, the Tresorit service goes the one-fell-swoop route: all the files in the folder you select are encrypted as you sync them with Tresorit's servers, and you control the encryption key, rather than Tresorit or anyone else, according to the company. The Tresorit site's security page provides details on the service's client-side encryption technique.

As I noted above, the Tresorit client is currently available only for Windows, but the company plans to release versions for the Mac and iOS devices. Also, Tresorit doesn't encrypt the files on the PC's hard drive; it encrypts the files only as they are transmitted to the company's servers and gives users control of the encryption key.

To download all your Google Drive files to a single zipped folder, check the box in the top-left corner of the list and select More > Download. Alternatively, check only the files you want to encrypt and transfer to Tresorit, and then choose More > Download.

A window shows the progress of the file zipping and download. You can have Google send you an e-mail when the download is complete.

After you download and install the Tresorit program, open the app and choose New Tresor in the bottom-left corner of the window. Click Browse and navigate to the folder containing the files you just downloaded from Google Drive. Click the Select Folder button, change the name of the Tresor (if you wish), and click Next.

You can share the Tresor with someone else, but that person has to download and install the program on their Windows PC. You're prompted to enter the recipient's e-mail address and to send them an invitation. Click Finish to create the Tresor and encrypt the files as they sync with the Tresorit cloud servers.

Subsequent syncs are performed automatically, or you can click the Sync Now button. You can also choose the option to disconnect from the computer.

The only settings available in the program let you sign out, uncheck the option to start Tresorit with Windows, and hide notifications (they're shown by default).

It took less than 30 minutes to download a 200MB Google Drive archive and upload it to a free Tresorit account. The files included Word documents, Excel spreadsheets, PowerPoint presentations, native Google files, text files, PDFs, and various image files.

When I tested Tresorit by sharing and synching folders between two PCs, some syncs took several minutes to complete while others were done in just a few seconds.

The files can be accessed only via the Tresorit program rather than through a browser. This restricts your ability to share files because the recipients have to download and install the Tresorit client. At least this limitation may prevent oversharing.

Tresorit offers 5GB of free storage. The company's support page indicates more storage and features are available for monthly fees, but it doesn't describe the features or state what the rates are.

The page suggests you contact Tresorit for more information, but the only e-mail address I could find on the English-language version of the site was on the Careers page and was addressed to the HR department. A request for information placed on the company's support forum went unanswered. The lack of contact information is troubling, to say the least.

Apart from the inability to contact the company, Tresorit ran without a hitch when I tested the program on a Windows 7 PC and a Windows 8 laptop. I felt confident enough in the encrypted Google Drive archive on Tresorit to delete the sensitive files I had stored in Google Drive.