Security tip #21 in our Christmas calendar is to delete data securely. When deleting data, it is important to make sure it’s completely wiped. Simply emptying the trash bin or running “rm” on a file doesn’t mean it’s fully deleted. The file can still be returned to its original state by very little work. In order to make it non-recoverable you should wipe your file with one pass, meaning you will overwrite it with 1’s before returning it to 0’s. Tools you can use to do this for Windows include sdelete, and shred for Linux. Those with a larger budget should of course consider a degauser, and those who simply want to completely destroy the entire hard drive should be sure to drive a screwdriver through the discs of the hard drive as burning or putting it in water won’t help you.