A trusted computer, for instance, would refuse to make unauthorized copies or to play audio or video selections for a user who has not paid for them. Although the techniques that render a system trustworthy are complex, the result is simple. At first, trusted security features would be bundled into a printer or handheld digital reader at some additional cost to the consumer, because they would provide the ability to access material of much higher value. Eventually the costs would fall as the technology became widely implemented. At Xerox and elsewhere, researchers have attempted to express the fees and conditions associated with any particular work in a formal language that can be precisely interpreted by trusted systems.
Digital rights fall into several natural categories.
Transport rights include permission to copy, transfer or loan. Render rights allow for playing and printing. Derivative-work rights include extracting and editing information and embedding it in other publications. Other rights govern the making and restoring of backup copies. Different intellectual works have different security requirements.