Rackspace US Inc v. PersonalWeb Technologies LLC

1. Case Identification

• Case #: IPR2014-00057
• Patent #: 5,978,791
• Filed: October 10, 2013
• Petitioner(s): Rackspace US, Inc. and Rackspace Hosting, Inc.
• Patent Owner(s): Personal-Web Technologies, LLC and Level 3 Communications, LLC
• Challenged Claims: 1-4, 29-33, 35 and 41

2. Patent Overview

• Title: Data Processing System Using Substantially Unique Identifiers to Identify Data Items, Whereby Identical Data Items Have the Same Identifiers
• Brief Description: The ’791 patent is directed to data storage systems that use "substantially unique identifiers" to identify data items. These identifiers are generated based on all of the data in a data item and only the data in that item, allowing for content-based, location-independent identification and management.

3. Grounds for Unpatentability

Ground 1: Anticipation by Woodhill - Claims 1-4, 29-33, 35, and 41 are anticipated by Woodhill under 35 U.S.C. §102(e).

• Prior Art Relied Upon: Woodhill (Patent 5,649,196).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Woodhill disclosed every limitation of the challenged claims. Woodhill described a distributed storage management system that used "Binary Object Identifiers" (BOIs) for managing file backups. Petitioner asserted that these BOIs were calculated from "all of, and only, the contents of the binary object," which directly corresponds to the "substantially unique identifier" of the ’791 patent. The BOIs in Woodhill were composed of a CRC value, an LRC value, and a hash value, all calculated from the content of the data item. For independent claim 1, Woodhill’s system met the "identity means" by creating these content-based BOIs. It met the "existence means" by comparing newly calculated BOIs against a "File Database" of existing BOIs to determine if a binary object had already been backed up, which is a determination of its presence in the system. Petitioner contended that Woodhill’s backup and restore functionalities inherently disclosed the limitations of dependent claims 2-4 concerning local existence, data association, and access means.

Ground 2: Obviousness over Woodhill - Claims 1-4, 29-33, 35, and 41 are obvious over Woodhill under 35 U.S.C. §103.

• Prior Art Relied Upon: Woodhill (Patent 5,649,196).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner presented this as an alternative ground in the event Woodhill was found not to anticipate every claim limitation. The argument relied on the same disclosures from Woodhill as cited for Ground 1. Petitioner contended that any minor differences between Woodhill's disclosure and the claim language would have been obvious to a person of ordinary skill in the art (POSITA). For example, a POSITA would have understood that determining whether a binary object needs to be backed up in Woodhill’s system is necessarily a determination of whether that object is already present in the backup repository, thus rendering the claimed "existence means" obvious. This reasoning was extended to all challenged claims, asserting that Woodhill's teachings, combined with the knowledge of a POSITA, rendered the claimed invention obvious.

Ground 3: Obviousness over Woodhill in view of Langer - Claims 1-4 and 29 are obvious over Woodhill in view of Langer under §103.

• Prior Art Relied Upon: Woodhill (Patent 5,649,196) and Langer (a 1991 Usenet newsgroup publication).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground addressed the possibility that the "identity means" of claim 1 could be narrowly construed to require a specific cryptographic hash function (e.g., MD5, SHA) as mentioned in the ’791 patent’s specification. While Woodhill disclosed a hashing algorithm, it was not MD5 or SHA. Langer, a Usenet posting, explicitly taught using the MD5 cryptographic hash of a file’s contents to create a unique, location-independent identifier. This was proposed to solve the same problem addressed by the ’791 patent: uniquely identifying files that may have different names or exist in different directories.
  • Motivation to Combine: Petitioner argued a POSITA would combine Woodhill’s data management system with Langer’s superior hashing method to improve the system's robustness. Langer provided an express motivation, stating that using a cryptographic hash like MD5 provides a "VERY secure means of ensuring they have got an uncorrupted version of the specific file." A POSITA would have been motivated to replace Woodhill's less advanced hash with MD5 to reduce the system's susceptibility to malicious content alteration.
  • Expectation of Success: The combination would have been a predictable substitution of one known hashing algorithm for another to achieve a known benefit (improved security and integrity verification), leading to a high expectation of success.

4. Key Claim Construction Positions

• Previously Construed Terms: Petitioner noted that the PTAB had already construed several key terms in a related IPR (IPR2013-00082) involving the same ’791 patent. Petitioner largely adopted these constructions, including:
  • "substantially unique identifier": Construed as "an identity for a data item generated being determined using and depending on all of the data in the data item, and only the data in the data item."
  • "identity means for determining...": As a means-plus-function term, the PTAB identified the function as determining the identifier and the corresponding structure as a "data processor programmed to perform a hash function, e.g., MD5 or SHA."
• Disputed Construction: Petitioner requested that the PTAB reconsider and revise its prior construction of one term:
  • "data associating means for making and maintaining...": Petitioner argued that the PTAB’s prior identification of corresponding structure for this term (from Fig. 11 of the ’791 patent) properly covered the "maintaining" function but omitted key aspects of the "making" function. Specifically, Petitioner asserted that the structure should explicitly include step S236, which describes creating a new entry in the registry when an identifier does not already exist, to fully capture the recited "making" function.

5. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-4, 29-33, 35, and 41 of Patent 5,978,791 as unpatentable.