A specific digital rights management (DRM) system designed for digital document protection is presented in some detail. Following some background information on document protection, the various technical measures employed by this DRM system are discussed. These technical measures include a variety of tamper-resistance methods, controlled execution techniques, encryption, digital watermarking and other techniques. The discussion of specific security features is followed by a discussion of several other current and developing DRM systems and technologies. Comments and conjectures on the limitations and future directions of the technology are made throughout.