Despite marketing claims to the contrary, the only sure way to eliminate data from a hard disk is to destroy the disk.
Claims by Robin Hood Software, the British developer of Evidence Eliminator, that its software is effective against forensic examination have been treated with scepticism by the rest of the industry.
Matthew Dalton, IT manager at law firm Phillips Fox, said he couldn't see how it could be done. "There's residual magnetism on a disk and it's physically there -- software can only go back to what's been written to the disk. I'd be very dubious about anything short of degaussing the hard drive." Degaussing is the practice of applying a strong magnet to the drive.
Evidence Eliminator cites a study by British data recovery specialist Vogon in which Vogon tested a variety of data-deletion methods, ranging from software to use of a hammer and electric sander. Evidence Eliminator said the test endorsed its software as effective against forensic searches of hard drives.
But Vogon boss Gordon Stevenson said "there is fact, fiction and marketing, and Evidence Eliminator's statement is somewhere between the latter two".
Stevenson said Vogon's test showed a cheap sander was more effective than the $NZ100 software. "Anyone who believes they have written software to eliminate 100 per cent of the evidence from a hard disk is technically naive."
Auckland data recovery company Computer Forensics said that Vogon was right to say data cannot be eliminated by software alone. "But you have to look at it from a practical point of view," said managing director Brian Eardley-Wilmot. "There are conventional, software-based data-wiping techniques and then there are the exotic ones.
"Using software tools and operating within the normal ambit of the PC, you can have a file on disk and its components can be totally overwritten. For normal conventional purposes, it can't be recovered.
"But there are exotic ways of recovering data that are very expensive and quite time-consuming, which involve peeling back the layers of overwrites and include sophisticated magneto-resistive techniques."