Personal Web Tech LLC v. NRT LLC

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: PersonalWeb Technologies, LLC (Texas) and Level 3 Communications, LLC (Delaware)
  • Defendant: NRT LLC (Delaware) and NRT NEW YORK LLC d/b/a Citi Habitats (Delaware)
  • Plaintiff’s Counsel: Stubbs, Alderton & Markiles, LLP
• Case Identification: 5:18-cv-05201, N.D. Cal., 10/04/2018
• Venue Allegations: Venue is alleged to be proper because the Defendants are Delaware limited liability companies, which the complaint asserts makes them residents of any judicial district in Delaware. The case was subsequently transferred to the Northern District of California by the Judicial Panel on Multidistrict Litigation for consolidated pretrial proceedings.
• Core Dispute: Plaintiff alleges that Defendant’s website and associated content delivery systems infringe four patents related to using content-based identifiers to locate, manage, and control access to data in distributed computer networks.
• Technical Context: The technology relates to content-based addressing, a method for identifying data files by their content rather than their name or location, which is foundational to modern cloud computing and content delivery networks for improving efficiency and data integrity.
• Key Procedural History: The complaint notes that PersonalWeb has previously enforced the patents-in-suit against third parties, resulting in settlements and non-exclusive licenses.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 6,928,442 - "Enforcement and Policing of Licensed Content Using Content-Based Identifiers"

The Invention Explained

• Problem Addressed: In distributed data processing systems, conventional methods of identifying data by name and location are inefficient and unreliable. The same data can have different names, or different data can have the same name, leading to data duplication and difficulty in verifying data integrity without context. (Compl. ¶¶15-16; ’442 Patent, col. 1:11-2:42).
• The Patented Solution: The invention proposes a system where data items are identified by a "substantially unique" identifier, termed a "True Name," which is generated by applying a cryptographic hash function (such as MD5 or SHA) to the content of the data item itself. (Compl. ¶¶17-18). This content-based identifier is independent of the data's name or location, ensuring that identical data items have identical identifiers and allowing for verification and management of data across a distributed network. (’442 Patent, col. 13:1-14:15).
• Technical Importance: This approach provided a method to manage data in expanding networks, reduce duplicate data, and control access to information based on its actual content, a key challenge in the development of large-scale distributed systems. (Compl. ¶16).

Key Claims at a Glance

• The complaint asserts independent claim 10 and dependent claim 11. (Compl. ¶58).
• Claim 10 includes the following essential elements:
  • A method in a system of distributed files across a plurality of computers.
  • Obtaining a name for a data file, where the name is based at least in part on a function of the data comprising the file's contents.
  • Using at least the name to determine whether a copy of the data file is present on at least one of the computers.
  • Determining whether a copy of the data file present on a computer is an unauthorized or unlicensed copy.
• The complaint does not explicitly reserve the right to assert additional dependent claims.

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U.S. Patent No. 7,802,310 - "Controlling Access to Data in a Data Processing System"

The Invention Explained

• Problem Addressed: The patent addresses the challenge of controlling access to and distribution of data in a networked environment, where data may be stored on or requested by various computers (e.g., servers, clients, caches). (’310 Patent, col. 1:12-2:46).
• The Patented Solution: The invention describes methods and systems for controlling content distribution using content-dependent names. When a device requests a data item, the request includes the item's content-dependent name. A controlling computer (e.g., an origin server) compares this name against a set of values to determine if the content is "unauthorized or unlicensed" and, based on that determination, either permits or denies access to the content. (’310 Patent, Abstract; col. 30:31-31:12).
• Technical Importance: The technology provides a framework for access control in distributed systems that is tied to the data's content, not its location, enabling more robust management of information across complex networks. (Compl. ¶20).

Key Claims at a Glance

• The complaint asserts independent method claim 20 and independent system claim 69. (Compl. ¶66).
• Claim 20 includes the following essential elements:
  • Controlling distribution of content from a first computer to another in response to a request.
  • The request includes a content-dependent name of a data item, based on a hash function of the item's data.
  • Based on the content-dependent name, the first device permits access if the content is not determined to be unauthorized or unlicensed.
  • Alternatively, it does not permit access if the content is determined to be unauthorized or unlicensed.
• Claim 69 recites a system operable to perform a similar method. (Compl. ¶¶70-72).
• The complaint does not explicitly reserve the right to assert additional dependent claims.

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U.S. Patent No. 7,945,544 - "Similarity-Based Access Control of Data in a Data Processing System"

• Technology Synopsis: This patent describes a method for determining a "digital key" for a file composed of one or more parts. The key is generated by first applying a function to the content of each part to get "part values," and then applying a second function to those part values. This hierarchical key generation allows for similarity-based access control and efficient data management. (Compl. ¶79).
• Asserted Claims: The complaint asserts claims 46, 48, 52, and 55. (Compl. ¶76). Claim 46 is an independent method claim.
• Accused Features: The accused features include Defendant's alleged two-step process of generating content-based fingerprints for individual asset files (part values) and then generating a content-based ETag for the webpage base file that includes the URIs of those asset files (the final digital key). (Compl. ¶79).

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U.S. Patent No. 8,099,420 - "Accessing Data in a Data Processing System"

• Technology Synopsis: This patent claims a system for managing access to data items in a network. For a given data item, the system determines one or more content-dependent digital identifiers. It then uses a database of identifiers to selectively permit or deny access to the data item, ensuring that it is not made available without authorization. (Compl. ¶¶90-91).
• Asserted Claims: The complaint asserts claims 25, 26, 27, 29, 30, 32, 34-36, and 166. (Compl. ¶87). Claim 166 is an independent system claim.
• Accused Features: The accused system is Defendant's network of web servers, which allegedly use databases of ETag values associated with file URIs to determine whether a requesting computer (e.g., a browser cache) is authorized to access cached content or must retrieve new content. (Compl. ¶92).

III. The Accused Instrumentality

Product Identification

• Defendant’s website located at "aptsandlofts.com" and the associated system and method for providing webpage content. (Compl. ¶32).

Functionality and Market Context

• The complaint alleges that Defendant’s system uses content-based identifiers to manage caching and efficiently distribute webpage content across a network of origin servers, intermediate cache servers, and end-user browser caches. (Compl. ¶¶33, 59). Specifically, the system is alleged to generate content-based "ETag" values for webpage files by applying a hash function to the file's contents. (Compl. ¶¶34, 43, 45). Additionally, it allegedly generates content-based "fingerprints" for asset files (e.g., images, scripts) and inserts these fingerprints into the filenames within the asset files' Uniform Resource Identifiers (URIs). (Compl. ¶¶35, 39).
• When a browser requests a webpage, it sends a conditional HTTP GET request including the ETag of its cached version in an "If-None-Match" header. (Compl. ¶¶47, 50). An upstream server compares this ETag to its current ETag for the file. (Compl. ¶51). If they match, the server sends an HTTP 304 "Not Modified" response, authorizing the browser to use its cached copy. (Compl. ¶52). If they do not match, indicating the content has changed, the server sends an HTTP 200 "OK" response with the new content and the new ETag. (Compl. ¶53). This process allegedly reduces bandwidth and server load by serving full files only when their content has changed. (Compl. ¶37).
• No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

U.S. Patent No. 6,928,442 Infringement Allegations

Identified Points of Contention:

• Scope Questions: The central dispute may concern the scope of the term "unauthorized copy or an unlicensed copy." The complaint equates this with a determination of cache validity (i.e., a stale file is "unauthorized"). (Compl. ¶62). However, the patent's title, "Enforcement and Policing of Licensed Content," and abstract suggest the term relates to intellectual property rights and permissions, not merely data freshness. A court will need to determine if "unauthorized" can be construed to cover content that is merely outdated.
• Technical Questions: What evidence does the complaint provide that Defendant’s system performs the claimed step of "determining" a file is "unlicensed"? The complaint's allegations focus exclusively on comparing ETags to check for content changes, which primarily addresses authorization to reuse cached data rather than a license to access the data in the first instance.

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U.S. Patent No. 7,802,310 Infringement Allegations

Identified Points of Contention:

• Scope Questions: As with the ’442 Patent, a key question will be whether determining that a cached file is stale is equivalent to determining that the content is "unauthorized or unlicensed" as required by the claim. The claim frames this as a binary decision to either permit or not permit access, which maps to the complaint's description of sending either an HTTP 304 or HTTP 200 response. The dispute will likely focus on the meaning and scope of the "unauthorized or unlicensed" condition.
• Technical Questions: Does an upstream server that receives a request from a downstream cache qualify as a "first device" that is "controlling distribution of content" in the manner claimed? A defendant may argue that the server is merely responding to a request according to standard HTTP protocols, rather than actively "controlling distribution" in the proactive sense potentially implied by the patent.

V. Key Claim Terms for Construction

• The Term: "unauthorized copy or an unlicensed copy" (from ’442 Patent, claim 10) and "unauthorized or unlicensed" (from ’310 Patent, claim 20).
• Context and Importance: The viability of the infringement claims may depend entirely on the construction of this phrase. Plaintiff's theory requires this term to be broad enough to encompass a determination that a cached file's content is stale or out-of-date. A defendant would likely argue for a narrower construction limited to determining whether a user or system has a legal right or license to access the content. Practitioners may focus on this term because the complaint's infringement theory hinges on equating cache validation with intellectual property policing.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The body of the specification describes systems for managing data integrity and consistency in distributed networks, such as synchronizing caches, which could be argued to be a form of "authorization" to use data. (e.g., ’442 Patent, col. 3:1-6). The functional steps described in the patent—obtaining a content-based name and using it to check status—are agnostic to the reason for the check.
  • Evidence for a Narrower Interpretation: The title of the ’442 Patent, "Enforcement and Policing of Licensed Content Using Content-Based Identifiers," explicitly links the invention to licensing. The abstract states, "A copy of a requested file is only provided to licensed (or authorized) parties," and that the "system may check one or more computers for unauthorized or unlicensed content." (’442 Patent, Abstract). The specification further describes a "license table" for identifying files that may only be used by licensed users. (’442 Patent, col. 8:52-56).

VI. Other Allegations

• Indirect Infringement: The complaint alleges that Defendant infringed "by its manufacture, use, sale, importation, and/or offer for sale of products or services, and/or controlling the distribution of its webpage content." (Compl. ¶¶58, 66). While the phrase "controlling the distribution" could suggest a theory of indirect infringement, the complaint does not plead separate counts for inducement or contributory infringement nor does it allege the specific facts required to support knowledge or intent for such claims.

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue will be one of definitional scope: can the phrase "unauthorized or unlicensed copy," which appears in patents with titles and abstracts focused on policing licensed content, be construed to cover a cached data file that is merely outdated or "stale" as determined by an ETag mismatch? Plaintiff's case may depend on establishing this broader meaning, while the patent's intrinsic evidence could support a narrower, IP-rights-based interpretation.
• A related evidentiary question will be one of functional purpose: does the accused system, which uses standard HTTP mechanisms like ETags and conditional GET requests for the technical purpose of ensuring cache coherency and efficiency, actually perform the specific method of "determining" authorization and "controlling distribution" for policing purposes as contemplated by the patents-in-suit? The case may turn on whether a routine cache validation check can be legally equated with the patents' described access control and content policing functions.