[Windows] 3 free programs to easily encrypt files stored in cloud storage (Dropbox, SkyDrive, Google Drive, Box, etc.) [Mac OS X, iOS, Android]

I’m sure many dotTechies use cloud storage service, at least sparingly if not frequently. One of the major concerns with cloud storage is the safety and privacy of data; no one wants their files, documents, etc. in the wrong hands. The best way to combat these concerns is to simply not use cloud storage. However, I’m sure that isn’t an option for some people. The second best way to address these concerns is by using encryption.

Encryption helps insure that even if your files are accessed by an unauthorized person, they won’t be able be able to open/read them (assuming you used a strong password and proper encryption). There are plenty of encryption programs out there, such as dotTech’s favorite TrueCrypt and AxCrypt. However, most encryption programs don’t have the cloud storage model in mind. They can be used to protect files stored in cloud storage yes, but they aren’t specifically designed for cloud storage files. So if you use cloud storage, you probably want to check out an encryption program specifically designed to help streamline encryption of files you are going to store in the cloud. That is why we have put together a list of three programs which can be used to do just that.


In terms of encryption, all of the following programs are nothing unique; they encrypt files just like other encryption utilities. What makes these programs different is the fact that they make it easy to encrypt files before uploading to cloud storage; they streamline the process.

That said, let’s being…

NOTE: All three of the following programs require that you must download the desktop program of your cloud storage service. They work by using cloud storage folders, so you need a program of whatever cloud storage service you use to use these programs — you cannot be one of those people that only uses cloud storage through the web.


BoxCryptor is a program that works by creating an encrypted “drive” (aka folder) inside a target folder. All files put inside that BoxCryptor drive are automatically encrypted using AES-256 and your selected password before the files are uploaded. The idea here is you must download the desktop program of the cloud storage service you want to use (you *must* download the desktop program of your cloud storage service, otherwise you cannot use BoxCryptor) and then have BoxCryptor create its encrypted drive inside the folder of the cloud storage service. From that point forward, when you want to store a file on your cloud storage service but want to store it encrypted, simply save the file in the BoxCryptor subfolder you created earlier and BoxCryptor encrypts the file before it is uploaded to the cloud storage service you are using.

The key to note with BoxCryptor is it stores files on your local computer as unencrypted; if you browse the files stored inside BoxCryptor’s encrypted drive, you will find that the files are not encrypted. What BoxCryptor does is it ensures files are encrypted when they are on stored on your cloud storage — it does on-the-fly encryption when files are uploaded. This means you can update/use/edit the files stored inside BoxCryptor’s encrypted drive on your local computer like normal; modified files will be synced properly with encryption. This also means you are still able to upload unencrypted files to your cloud storage service — files that you put in your cloud storage service’s folder but not in the BoxCrypt subfolder.

BoxCryptor has official support for Dropbox, Google Drive, SugarSync, Skydrive, and Box — it will automatically detect their folders on your computer if stored in default location. However, BoxCryptor also has the ability to be pointed to a custom folder meaning it may work with other cloud storage services, too.

With the free version of BoxCryptor you can only have one encrypted drive — and thus it can only be used with one cloud storage service; the free version also won’t encrypt filenames and is for non-commercial use only. If you want to encrypt filenames and want unlimited encrypted drives, you need to upgrade for $44.99 to BoxCryptor Unlimited or $99.99 if you want business use.

BoxCryptor is available on Windows, Mac OS X, Windows RT, Android, and iOS. Take note the mobile versions of the program don’t have as many features as the desktop versions.


CryptSync is similar to BoxCryptor in the sense that it requires you to download the desktop program for the cloud storage service you want to use. However, CryptSync works differently.

How CryptSync works is you pick two folders. CryptSync syncs the files from folder A (“original folder”) to folder B (“encrypted foldeR”), ensuring all files in folder B are the same as folder A (including new and updated files). The catch is files in folder A remain unencrypted while files in folder B are encrypted by CryptSync. The idea here is for you designate your cloud storage’s folder (e.g. Dropbox folder) as folder B, so all files you add/update in folder A are synced with the cloud storage service you are using but are synced in encrypted form. This means files on your computer are unencrypted on folder A but encrypted on the cloud storage service’s server.

The key to note about CryptSync is it syncs from folder A -> folder B, not the other way around. This means you are still allowed to upload unencrypted files to your cloud storage service — just place them directly into folder B as opposed to into folder A.

The best part about CryptSync is that it uses 7-zip to encrypt files which means not only is AES-256 being used but you can also easily decrypt encrypted files without CryptSync — you just need 7-zip or any other archive tool that can open encrypted 7z archives.

CryptSync does not have specific support for any cloud storage services; it works with any and all cloud storage services that have desktop programs with folders. This includes Dropbox, Google Drive, SugarSync, Skydrive, and Box. You can also, potentially, use it for non-cloud storage purposes (such as maybe a networked folder).

CryptSync is completely free for everyone to use (it is open source) and you are not restricted on the number of folders you can use it with. In other words, you can use it with multiple different cloud storage services if you desire. And, it gives you the option to encrypt file names, if you want.


CloudFogger is very similar to BoxCryptor but with one major difference: CloudFogger does not create an encrypted subfolder, it encrypts all the files inside your cloud storage folders.

CloudFogger works by you designating a cloud storage folder (if CloudFogger does not automatically detect it) and performing on-the-fly encryption (using AES-256) of all files inside that folder when the files are uploaded to cloud storage. Like BoxCryptor, the files are in unencrypted format on your computer but are encrypted when stored in the cloud.

CloudFogger can work with as many folders/cloud storage services as you want and it is free for all to use. There is no official list of supported cloud storage services but it is known to work with Dropbox, Google Drive, Box, and SkyDrive. In theory, CloudFogger will work with any cloud storage service that has a desktop program with folder — it allows you to manually designate cloud folders, if CloudFogger is unable to find them on its own.

One feature of CloudFogger that is different than both BoxCryptor and CryptSync is the fact that it can be used as a traditional file encryption tool: you can use CloudFogger to encrypt individual files (non-cloud storage files), just like what AxCrypt does. CloudFogger adds an entry in right-click context menu to make this easy.

It is important to note CloudFogger requires you to create a (free) account before you can use it. With this account comes a caveat: your files are being synced to CloudFogger’s servers (in encrypted format, according to the developer) along with your respective cloud storage. Why is the developer storing your files on his/her server? I’m not sure but it may have to do with the fact that CloudFogger wants you to be able to access your files on all your devices UPDATE: CloudFogger does not store your files on their own servers. CloudFogger has Windows, Mac OS X, iOS, and Android versions. (iOS and Android versions can only view files, not upload.)


BoxCryptor, CryptSync, and CloudFogger are all great programs. However, if I were to pick out of BoxCryptor, CryptSync, and CloudFogger, I’d probably pick CryptSync because

  • It is open source and free for all to use, without restrictions (i.e. it does not limit you to just one folder like BoxCryptor’s free version);
  • It does not store your files on the developer’s server (like CloudFogger);
  • It uses 7-zip to encrypt files, making it easy to decrypt if ever necessary;
  • I really like the idea of having two folders for cloud storage, one folder which you can store all the files you want to be encrypted and other folder you can store the files you don’t want to be encrypted.

However, BoxCryptor and CloudFogger are viable options, too. You can download all three programs from the links below.

Version reviewed: 1.5

Supported OS: Windows, Mac OS X, Android, iOS

BoxCryptor homepage

Version reviewed: 1.4

Supported OS: Windows, Mac OS X, Android, iOS

CloudFogger homepage

Version reviewed: 1.0.5

Supported OS: Windows

CryptSync homepage

Related Posts

  • Gwen

    For anyone considering using CryptSync, please read ticket #136 on its SourceForge page. There are unpatched security vulnerabilities.


  • pubi

    With CryptSync – despite its name – you loose the cloud syncing service’s sync part… It then becomes an online encrypted backup. It is because CryptSync makes a one-direction sync: regular files to encrypted files and then the encrypted files will be uploaded. If another user edit the files from the cloud on a different device it then will be synced back to the encrypted folder but not to the original regular files folder.

  • Jay

    Copy . com offers (15GB + 5GB + 2 GB = 22GB) for free


    This is the best free cloud storage as of now.

  • Kanti

    Wouldn’t using CryptSync mean you will have duplicate storage on your PC and thus taking up double the space on your PC?

  • chucklw

    RE: Crypt Sync,

    There are 2 versions available for download,
    CryptSync-1.0.9.msi and CryptSync64-1.0.9.msi.

    do I use the “…64” for windows 64 bit?



  • Ashraf

    [@Roo] Yes that is what I meant. I’m surprised no one has yet to point out that typo… Thanks! Fixed now.

  • Roo

    [@Roo] Oops, nevermind — I didn’t notice this was already addressed in a prior comment — would be good to update the article though!

  • Roo

    In your conclusion, did you mean to say that CryptSync DOES NOT store its files on the developer server?

  • Jon

    I also want to say that there seems to be an equivalent of cryptsync for mac http://www.greenworldsoft.com/

    There is another option of using local encryption program (such as axcrypt) and then using a separate file sync program. But cryptsync does both of these tasks combined quite well for backup purposes.

  • Jon

    Yes, it should read “It does NOT store files on the developer’s server”

  • Vaards


    Hand made! ;)

  • ben

    20 GB of cloud storage at copy.com with this link.

    I know that there are many links out there. Why hould you use my? Well, it is as good as every other referral link out there since it gives you 5GB extra storage (so you get 20 GB). BUT it was created with love and you will make me very happy. :cool:

    With this link you get 20 GB cloud storage, so you (and me too) gain 5 GB extra compared to the default registration. Thx.


  • Skum4j

    I think the best is dropbox and copy.
    Dropbox give only 2,5 GB on start but interface is very good – GET START DROPBOX http://db.tt/jqef8Cnx or Copy.com give 20 GB on start :) https://copy.com?r=lFR3pg

  • art


    AFPhy6 , if you don’t see the reason for encryption just Google up Edward Snowden, you’ll be amazed.

  • Liam

    Copy.com give 15Gb to start with plus 5Gb for each referral, so possible to get tons of free storage!

    Start with 20Gb by using my link


  • Vaards

    Copy.com is offering three times more (seems limited time) pressing and sharing refferals. So, whooping 20 GBs!

    And first testing with my account makes feeling – extremely good service.

    Enjoy your 20 Gigs: https://copy.com?r=rn2dqd

  • M S

    I am also curious if any encryption programs for cloud storage , or the cloud storage folders themselves, can run off a flash drive like a portable app.
    Why? Because (one scenario) that way, students could use encrypted cloud storage on any campus computer, not just their person computers.

  • M S

    Ashraf, have you had a chance to test Cryptsync on Copy.com ? I’m waiting to read about your copy.com tests before I start using cloud storage (encrypted, of course). Thanks!

  • Gerry

    [@AFPhy6] You might want to try Copy.Com at the moment it is offering 5 GB free and if you follow the link you get an etra 5 GB, share the love. https://copy.com?r=UGKJyY

  • Godel

    “[CryptSync] It does store your files on the developer’s server (like CloudFogger);”

    More correction needed. ;)

  • AFPhy6


    EXCELLENT point, Ashraf! Files you wish to share with others are very likely to be unencrypted. Thanks for making that point. Since I have not been using the cloud storage services at all, I had not considered that aspect.

  • Ashraf

    [@Brian] Odd. I swear I read otherwise. I suppose I should have properly double-checked. Thanks, fixing article now.

  • Brian


    According to their knowledge base article entitled, “What type of encryption does Cloudfogger use?” they don’t store files on their server:

    “Also, we do not store or have access to your encrypted data. Your data is encrypted on your client and stored at your cloud storage service which means that there is a physical layer between the encryption service and the storage location of your data.”

  • Ashraf

    [@AFPhy6] I agree that for storage purposes, everything on the cloud should be encrypted. My thinking is some people will want to share some files with others. Using encryption when sharing files is a bit annoying.

    [@chucklw] I believe BoxCryptor and CloudFogger both allow access on Android, but I haven’t tried it myself so I’m not sure.

    [@Godel] I’m 100% sure — I read it on CloudFogger’s own website, although I can’t think of where off the top of my head. If I find it, I’ll link it to you.

  • Godel

    With this account comes a caveat: your files are being synced to CloudFogger’s servers (in encrypted format, according to the developer) along with your respective cloud storage. Why is the developer storing your files on his/her server?

    Umm, are you sure this is the case? I’ll admit Cloudfogger don’t make it any easier by NOT HAVING A COMPLETE AND COHERENT MANUAL for us to read (and yes, I was shouting).

    I was under the impression the Cloudfogger account was mainly about sharing credentials for syncing, which in itself might be some cause for concern.

  • chucklw

    Happy April Fools Day!
    So, where do you really live?

    As far as cloud storage, are these files accessible from Android devices on any of these products?
    The impression I get is no, but wanted to check.

    Thanks, as always,


  • AFPhy6

    I picked up an academic “cloud storage” account so long ago now I’ve lost track of the exact time… maybe twelve years ago. Totally lost track of that account. Recently I have grabbed a couple “free Gb” accounts, but something has held me back all this time, and these products address that number one concern.

    I will probably grab a copy of CryptSync for the reasons you delineate above, Ashraf, and test it out. It is very very important, whenever encryption is involved, to have full control of the encryption methodology, and the open source model assures that I will. Only time will tell whether CryptSync is sufficiently convenient for me to actually start using the cloud, but this sounds like the right track for me.

    Thanks, Ashraf, for getting this program out in front of us today.

    I know that some don’t see the reason for encryption at all, but if you have ever had a twinge of concern that Google (for example) tracks sites you visit, I suggest that you ought to have concern about the storing unencrypted files in the cloud for exactly the same reasons, and even unencrypted filenames only. (Consider how military spies piece together significant information from many disparate nearly insignificant parts.) I would not choose to store anything in the cloud without encryption, so in this I disagree with Ashraf.