Cloud storage services such as Dropbox, Google Drive, and SugarSync are convenient, efficient--and notoriously insecure. Files are rarely encrypted, data transfer is typically not protected, and companies are usually able to access your files (even if they state they won't, they may be legally compelled to do so).
Documents such as business plans or other sensitive files (say, a copy of your birth certificate) should be protected. You can utilize a special, ultra-secure provider such as Wuala or Tresorit, or you can encrypt files yourself before uploading them to larger storage services, such as Dropbox.
Price: 5GB Free; Plans starting from 20GB for $4/month
Platforms: Windows, Linux, iOS, Android
Wuala is a secure cloud storage service offered by storage company LaCie. This service differs from mainstream cloud storage providers in two ways:
Client-side encryption of files: All of your files are encrypted locally on your device before being sent to the cloud, which ensures that even on a non-encrypted transfer, no readable data would leak out. This process is more secure than a secure transfer, mainly because it means that nobody except you ever has access to your data.
Zero-knowledge password policy: Only you know your password, and therefore only you can access your account. Wuala's employees cannot see your password, nor can they see your data except in raw form (how many files you have and how much storage space they take up). So even if the government came knocking on Wuala's door and asked them to turn over your files, they simply wouldn't be able to do so. Nor will you be able to get to your stuff if you forget your password, so keep it carefully.
Security aside, Wuala operates like the cloud storage services you're used to. Simply download Wuala's application and the service will install a special sync folder to your device, where you can drag and drop files to store both locally and in the cloud. Wuala also offers backup and versioning, which means you'll be able to access previous versions of files or restore files should you accidentally delete them. Like other cloud storage providers, Wuala offers 5GB of storage for free. Pricing plans start at 20GB for $4 per month.
Price: 5GB Free; Plans starting from 100GB for $7/month
Platforms: Windows, Mac OS X, iOS, Android
Tresorit is a cloud storage provider that claims to offer "a truly secure cloud storage service." Security features include client-side encryption, secure data transfer, and secure data centers that are equipped with physical security measures against intrusion as well as uninterruptible power and backup systems.
Like Wuala, Tresorit encrypts your data on your local machine to help ensure that your files are protected at all times. It, too, practices a zero-knowledge password policy, which means that nobody in the company can ever access your password or decryption keys. Of course, the drawback of such a policy is that if you forget your password, you're basically out of luck (you'll have to create a new account, and you'll lose all of your data in the cloud).
Tresorit's main difference from Wuala, and other mainstream cloud storage services, is the ability to turn any folder on your device into a secure "tresor." What this means is that you do not have to drag and drop files into a special sync folder. Instead, you can simply right-click on an existing folder and "tresor it." This is especially convenient if you're digitally organized and you'd prefer not to rearrange your files into one sync-able folder.
Tresor offers 5GB of space for free. An additional 100GB will cost you 5 euros, or just under $7, per month.
McAfee Personal Locker
Price: 1GB free with a subscription to McAfee LiveSafe
Platforms: Windows 8, iOS, Android
McAfee's Personal Locker is a cloud storage vault that you manage via your smartphone or Windows 8 device. It can store up to 1GB of data, which you can access from anywhere--but only after you've jumped through a series of security hoops.
The app requires voice recognition, biometric data (facial recognition), and a PIN to verify your identity before giving you access to your files. Every. Single. Time. You can choose to set certain files as low priority (you'll only have to enter a PIN to access them), but where's the fun in that?
While definitely not the sort of service you want to use for everyday cloud storage, Personal Locker would work well for sensitive documents that you may need to access from anywhere, such as legal documents, medical records, or copies of your passport or birth certificate. Personal Locker is free with a subscription to McAfee LiveSafe, which costs $80 per year.
Encrypt files locally
Switching to a different cloud storage provider can be frustrating, time-consuming, and potentially a bad financial decision especially when providers such as Copy offer 20GB of free storage right off the bat. If you'd rather not start from scratch, you can still use client-side encryption to keep your files safe and secure, while continuing to use your insecure, mainstream cloud storage provider. Free applications such as TrueCrypt, for instance, will let you encrypt your files inside your Dropbox folder. You'll need TrueCrypt installed on any device you want to access the files from, too. For more tips on encrypting your files, check out our guide on how to encrypt (almost) anything.