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We sugg=t a practical and economical way to generate random bits using a computer disk drive * a source of randomn-.It requirw no additiond hardware (given a system with a disk), and no user involvement. As a concrete example of performance, on a Sun Wtra-1 with a Seagate Cheetah disk, it generatw bits at a rate of either 5 bits per minute or 577 bits per minute depending on the physical phenomena that we use = a source of randomness. The generated bits are random by a theoretical argument, and *O pass a severe battery of statiaticrd twts.

Abstract. Most people consider frequent software updates a nuisance. However, we show how this common phenomenon can be turned into a feature that protects against software piracy. We define a protocol for "drop-in" upgrades of software that renders a large class of software piracy more traceable. A novel feature of our approach is a software aging technique by which we force the updates to occur, or else the software becomes decreasingly useful over time.