US 5,638,443 · Granted 1997-06-10

Xerox's 1997 Blueprint for Digital Rights Management

Imagine a digital file as a locked box with instructions on the outside. This patent describes a way to organize those instructions so that whenever someone tries to open the box, the system automatically checks what they're allowed to do with it. It's like a permission slip built into the file itself.

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The plain-English version

What it protects

The claim covers a system for organizing digital works into a tree-like structure where each piece has its own usage rights attached. What's protected here is the specific method of splitting a digital work into a description part (containing access rules and permissions) and a content part (the actual data), along with the way a repository or server checks those permissions whenever someone requests access. Anyone creating a digital file system that mimics this architecture of embedded rights-checking would potentially infringe.

Why it matters

This patent arrived at a pivotal moment in the mid-1990s when digital distribution was exploding but creators had no reliable way to control how their work was copied and shared. Xerox was staking out intellectual property around the core idea of baking access controls into the file structure itself—a foundational concept for what later became digital rights management (DRM) systems. It represents early thinking about how to make digital content behave like physical goods, with built-in rules about who can use it and how.

Real-world use

When you purchase an ebook and the retailer prevents you from copying it to unlimited devices, or when a streaming service limits how many screens can play simultaneously, those restrictions trace back to ideas like the one in this patent.

Original USPTO abstract

A system for controlling use and distribution of composite digital works. A digital work is comprised of a description part and a content part. The description part contains control information for the composite digital work. The content part stores the actual digital data comprising the composite digital work. The description part is logically organized in an acyclic structure, e.g. a tree structure. For a composite digital work each node of the acyclic structure represents an individual digital work or some distribution interest in the composite digital work. A node in the acyclic structure is comprised of an identifier of the individual work, usage rights for the individual digital work and a pointer to the digital work. Composite digital works are stored in repositories. A repository has two primary operating modes, a server mode and a requester mode. When operating in a server mode, the repository is responding to requests to access digital works. When operating in requester mode, the repository is requesting access to a digital work. A repository will process each request to access a composite digital work by examining the usage rights for each individual digital work found in the description part of the composite digital work.

Patent details

Publication number: US 5,638,443
Filing date: 1994-11-23
Grant date: 1997-06-10
Assignee: Xerox Corporation
Inventor(s): STEFIK; MARK J., BOBROW; DANIEL G., PIROLLI; PETER L. T.
CPC class: H04N21/44012

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