Many attorneys are using cloud computing to make their practices mobile and easier to access from various locations. There are definite concerns about the security and privacy of files stored in the cloud. Those concerns, however, are secondary to whether you properly secure your work computer and encrypt your files.
Any computer you use for work should have password protection. When you boot up, or try to wake up your computer, make sure you require a password. To change your security settings on a mac, simply go into system preferences>security>and check “require password to wake this computer from sleep or screen saver.”
You may also want to go into system preferences>energy saver. You can set your computer to sleep after short periods of inactivity. Lastly, consider setting up a “hot corner” which will automatically put the computer to sleep. This can be done under system preferences> desktop & screen saver>hot corners. Get in the habit of using the hot corners to put your computer to sleep (and therefore password protected) when you are away from it.
On a mac, go into system preferences>security>FileVault and turn it on. This will take a long time, so I advise doing this in the evening when you leave work, or when you do not need your computer for a few hours. FileVault encrypts your entire home directory. Every time you boot up or shut down your computer, all of your files are encrypted and can only be viewed after entering the password.
FileVault will slow a computer down, and there are reports that it can still be hacked. This, of course, would require that someone steals the computer and has the capabilities to hack into it. FileVault is not the perfect encryption software, but it is free, and by most accounts, it is relatively secure. At a minimum, it adds another level of security to your files.