Federal Circuit Affirms PTAB: Centripetal Networks Cybersecurity Patent Anticipated by Cisco User Guide

The U.S. Court of Appeals for the Federal Circuit (CAFC) on April 2, 2026 affirmed the Patent Trial and Appeal Board’s (PTAB) final written decision finding claims of U.S. Patent No. 10,284,526, held by Centripetal Networks, LLC, unpatentable as anticipated. The decision, authored by Judge Lourie, arose from an inter partes review (IPR) petition filed by Keysight Technologies, Inc., and upheld the PTAB’s determination that a Cisco Systems product documentation manual constituted qualifying prior art that disclosed every element of claim 1. The ruling carries significant implications for how vendor technical documents function as prior art in cybersecurity patent litigation.

The ‘526 patent covers methods and systems for network security that involve selectively decrypting data packets, analyzing their contents, taking a corresponding action, and forwarding packets to their intended destinations. Centripetal Networks, a company focused on network threat intelligence and security products, asserted the patent against Keysight Technologies, a major manufacturer of network testing and analysis instruments. Keysight responded by petitioning PTAB for IPR, arguing claim 1 was anticipated by prior art. The PTAB agreed in its final written decision, and Centripetal appealed to the Federal Circuit.

The critical prior art document was the Cisco IronPort AsyncOS 7.1 User Guide (IPUG). Centripetal challenged the PTAB’s finding that IPUG qualified as a printed publication publicly accessible before the patent’s priority date. The Federal Circuit rejected this challenge, citing archived webpage evidence and expert testimony establishing that practitioners of ordinary skill in the relevant field would consult vendor technical documentation. The court found substantial evidence supporting the PTAB’s conclusion that IPUG was publicly available prior to the ‘526 patent’s priority date.

The central claim construction dispute centered on the phrase “performing a corresponding action” in claim 1. Centripetal argued the PTAB improperly construed this phrase to include merely “allowing” a packet to pass through the system—a reading that, Centripetal contended, rendered the subsequent “transmitting” limitation superfluous. The Federal Circuit disagreed. The court reasoned that “allowing” a packet represents the inverse of “blocking” it, and that both constitute valid corresponding actions. The court further explained that re-encryption and transmission are distinct steps occurring after the corresponding action is performed, and therefore the transmitting limitation retains independent meaning even under the broader construction.

On the anticipation question, the CAFC found substantial evidence that IPUG disclosed all limitations of claim 1: the allowance, blocking, or redirection of packets; re-encryption; and forwarding to the intended destination. The court reviewed the PTAB’s analysis of the Cisco IronPort system’s operation and concluded that the workflow described in IPUG satisfied each claim element under the correctly construed terms. All of Centripetal’s arguments on appeal were found unpersuasive, and the PTAB’s determination of unpatentability was affirmed.

Two practice points emerge from this decision. First, the ruling reinforces that product manuals, configuration guides, and technical specifications published by vendors are legitimate and potent prior art references in IPR proceedings. Combining archived web evidence with expert testimony about industry customs for consulting such documents is an effective evidentiary strategy for establishing public availability. Second, cybersecurity patent claims directed to broad packet processing operations—particularly when drafted without specific technical differentiation from commercially available system workflows—face elevated anticipation risk when mature vendor documentation predates the patent’s priority date.

Centripetal Networks has built an extensive portfolio of network security patents and has filed suit against multiple major technology companies in prior proceedings. The Federal Circuit’s decision in this case may constrain the enforceability of similarly constructed claims in the portfolio. For Keysight Technologies, the ruling resolves a significant IP uncertainty in its network security testing product line. The decision was reported by IPWatchdog as part of broader coverage of Federal Circuit PTAB-related rulings.