Invalidity dossier
US 5825891
Added 9/21/2026, 9:24:37 AM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US5825891A — "Key Management for Network Communication"
Title: Key management for network communication
Patent number: US5825891A
Application number: US08/959,919
Inventors: Roger H. Levesque; Jeffrey A. Kraemer; Ashok P. Nadkarni
Original assignee: Raptor Systems Inc
Current assignee (per source): Clouding Corp
Priority date: 1996-01-16
Filing date: 1997-10-29
Publication/grant date: 1998-10-20
Status: Expired – Lifetime; anticipated expiration 2016-01-16
Classifications: H04L63/00, H04L63/02 (firewalls), H04L63/0227 (filtering policies), H04L63/0272 (virtual private networks)
Prior art keywords: computer, network, tunnel, firewall, computers
Purpose and plain-language scope (from the supplied text): The patent concerns key management for network communication. Based on the title, classification tags, and prior-art keywords, it relates to cryptographic key handling across a computer network, situated in firewall and virtual-private-network contexts and involving network "tunnels." The classifications indicate separation of internal from external network traffic, filtering policies, and VPN architectures.
What the excerpt does not establish: The supplied text is a Google Patents bibliographic/classification page, not the specification or claims. It therefore does not establish the actual claimed invention, claim language, claim scope, embodiments, algorithms, or figures. No abstract or detailed description is included, so the precise mechanism of "key management" cannot be confirmed from this excerpt alone. The title, classifications, and prior-art keywords are suggestive only.
Per the operating rules and to avoid inventing facts, no analysis is offered here of litigation, assignment/ownership transfers beyond the dates listed, validity, enforceability, or prior art. The excerpt lists litigation and PTAB entries and multiple reassignments, but these are referenced only as present in the source, not evaluated. Dates labeled as assumptions by the source (priority date, legal status) are reproduced as such.
Source: https://patents.google.com/patent/[US5825891](/patent/US5825891)/en
Generated 10/1/2026, 10:02:29 PM
Cases on file (0)
Specific litigation cases in our database that name US patent 5825891. The free-form analysis below may also discuss cases beyond this list.
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Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.