I bought a fairly powerful neodymium magnet a while back, and I wondered if I could use it to thoroughly wipe a hard drive from the outside simply by moving the magnet around the body of the drive. This would be primarily for wiping small laptop drives. Large hard drives are easy enough to dismantle and remove the platters, so wiping those platters with the magnet and then destroying them isn't a problem.
And while we're on the subject, are flashdrives ferrous based? IOW, could I erase those with the magnet as well?
Many thanks for your help and thoughts on the subject of drive security.