Equipping your PC with a firewall and antivirus tool may keep out most hackers, but doesn't guarantee your security. If someone gets physical access to your system (it's stolen, say, or a computer repair technician is snooping around) then the best internet security suite will be no use at all, and there's only one way to ensure you're protected: encryption.

Here are five free tools to encrypt your data to ensure they can't be accessed by hackers, no matter where they're stored.

Comodo Disk Encryption 1.2

Comodo Disk Encryption not only allows you to create a virtual encrypted drive that will hold your most confidential files but also lets users encrypt an entire partition of their hard drive. Comodo Disk Encryption then won't even let your system start until you've entered the password, and you can optionally require authentication with a USB memory key as well.

TrueCrypt 7.0a

TrueCrypt is a software system for establishing and maintaining an on-the-fly-encrypted volume (data storage device). On-the-fly encryption means that data is automatically encrypted or decrypted right before it is loaded or saved, without any user intervention. No data stored on an encrypted volume can be read (decrypted) without using the correct password/keyfiles or correct encryption keys. The entire file system is encrypted (such as file names, folder names, contents of every file, free space, meta data and so on).

AxCrypt 1.7 (32-bit)

AxCrypt is surprisingly straightforward in operation. It doesn't require any configuration, at all. If you want to encrypt a file, just right-click it, choose the new AxCrypt menu and select one of the Encrypt options, enter your passphrase, and that's it. The file will be protected with AES 128bit encryption, and no-one else is going to view it unless they know the passphrase.

Boxcryptor 1.0

The news that Dropbox is changing its terms and conditions to allow the company to hand over your backed up to the authorities if required has led to much murmurings of discontent. There's no doubt that online backup is increasingly popular - and for good reason - but if you're worried about the contents of your files falling into the wrong hands, you'll want to consider your options carefully. One answer is to use a program like Boxcryptor that allows the user to create an encrypted folder and then synchronise that folder with your online backup provider whoever it is.

SecretSync Beta 0.169

Alternatively, try SecretSync, which lets you copy your sensitive files to the SecretSync folder via its desktop or Start menu shortcut, and then they'll be encrypted. By storing the SecretSync folder in your Dropbox folder, you can back it up to your Dropbox account, secure in the knowledge that the data's encrypted in such a way that no third-party is going to get hold of it on Dropbox's say-so.