Dolby Laboratories Inc v. Intertrust Technologies Corp

1. Case Identification

• Case #: IPR2020-01273
• Patent #: 7,340,602
• Filed: July 16, 2020
• Petitioner(s): Dolby Laboratories, Inc.
• Patent Owner(s): Intertrust Technologies Corporation
• Challenged Claims: 25-26

2. Patent Overview

• Title: Systems and Methods for Fault-Tolerant Authenticated Broadcasting
• Brief Description: The ’602 patent discloses systems for verifying the authenticity of a cryptographically-signed electronic communication "on-the-fly." The technology uses a signed chain of check values, allowing a recipient to authenticate portions of a data stream before the entire communication is received, and incorporates error-check values to provide fault tolerance against transmission errors.

3. Grounds for Unpatentability

Ground 1: Claims 25 and 26 are obvious over Schneier.

• Prior Art Relied Upon: Schneier (Patent 5,978,475).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Schneier, which discloses a method for generating a secure audit log, taught all limitations of the challenged claims. Schneier’s system creates sequential log entries, each containing encrypted data, an unkeyed hash value derived from the previous entry (a "check value" in a "progression"), and a keyed message authentication code (MAC) that authenticates the hash value (an "error-check value"). Petitioner asserted that Schneier's MAC is inserted "in proximity" to its corresponding data and is operable to authenticate both the data portion and the check value, ensuring fault tolerance. It was further argued that a person of ordinary skill in the art (POSITA) would find it obvious that each log entry could be authenticated upon receipt without waiting for the entire log.
  • Motivation to Combine (for §103 grounds): This ground is based on a single reference, asserting Schneier alone renders the claims obvious.
  • Expectation of Success (for §103 grounds): Not applicable for a single-reference ground.

Ground 2: Claims 25 and 26 are obvious over Schneier in view of Haber.

• Prior Art Relied Upon: Schneier (Patent 5,978,475) and Haber (Patent 5,136,646).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground was presented as an alternative in case the term "fault tolerance" is construed to require the error-check value to be a direct hash of the data portion, as described in the ’602 patent’s specification. Schneier teaches a secure audit log system and mentions the option of appending a hash of the data to the data itself. Haber teaches a method for time-stamping documents where a pre-computed hash of a document is used in a subsequent hash chain calculation. This combination allegedly teaches using the hash of a data portion as an error-check value that authenticates the data and is also used to calculate the next check value in the progression.
  • Motivation to Combine (for §103 grounds): A POSITA would combine Haber's more efficient hashing technique with Schneier’s flexible system. Schneier’s hash chain equation is exemplary, leaving its specific implementation open. A POSITA would recognize that substituting the large encrypted data block with its smaller, pre-computed hash (as taught by Haber) in the hash chain calculation is a simple, known technique to improve computational efficiency and conserve resources.
  • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success, as the combination involves the simple substitution of one known element (encrypted data) with another known, more efficient element (a hash of that data) to achieve the predictable result of a faster, less resource-intensive authentication process.

4. Key Claim Construction Positions

• "whereby the user's system is able to receive and authenticate portions of the encoded block of data before the entire encoded block of data is received": Petitioner argued this clause is a limiting requirement of the method. The proposed construction requires "transmitting portions of the encoded block of data, check values derived from the portions, and a signature to authenticate the portions before the entire encoded block of data is transmitted."
• "in proximity": Petitioner contended that the claims are invalid under any construction of this term. Petitioner noted that Schneier's MAC (error-check value) and hash value (check value) are adjacent to the data they secure, thus meeting the proximity requirement. Petitioner argued it would be an obvious design choice to arrange these elements in any order, including without an intervening check value.
• Other Terms: For terms like "generating a progression of check values" and "each error-check value being operable to facilitate authentication," Petitioner adopted the plain and ordinary meaning as proposed by the Patent Owner in co-pending district court litigation for the purposes of the inter partes review (IPR).

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. §314(a) based on Fintiv factors was not warranted.
• Core Argument: Petitioner asserted it would seek a stay of the co-pending district court litigation. Further, the court's trial date was projected to be after the Final Written Decision (FWD) in the IPR, the court had not yet issued any substantive orders, the invalidity grounds in the litigation differed from those in the IPR, and the parties in related proceedings were not the same. Finally, Petitioner claimed the merits of the asserted grounds were particularly strong, weighing heavily in favor of institution.

6. Relief Requested

• Petitioner requested institution of an IPR and cancellation of claims 25 and 26 of the ’602 patent as unpatentable.