The Great Zero Challenge

[Dan Beale-Cocks]

Why, whenever hard drive deletion is mentioned, do sensible people 
forget anything they know about attack models and cost-benefit?

You cannot prove that data on a disc that has been over written is 
unrecoverable, but that won't matter for most users.  Anyone who thinks 
CESG is going to attack their hard drive will have enough money to 
over-write, degaus and then grind all hard drives.  Anyone else will be 
satisfied with a single overwrite of all zeros,  especially if that's 
done using ATA commands.