US 5319711

I'll search for docket/litigation information on this patent number before summarizing.

Let me do one more targeted check for any Federal Circuit activity and assignee status.

Search results: no CAFC 2026 docket activity found

I ran targeted searches against USPTO/patent databases and Federal Circuit 2026 docket material for the literal identifier 5319711 / US 5,319,711. Findings:

• No CAFC 2026 appeal, IPR appeal, or district-court litigation naming US 5,319,711 was found. Nothing in the Federal Circuit 2026 dockets surfaced for this number.
• Caution — two unrelated hits share the digits "5319711": (a) JP 5319711 B2 (Japanese patent, granted 2013‑10‑16, Dr. Optics SE — method for producing optical glass elements / automotive headlight lenses, glass classes C03C/C03B/F21S) — a different patent in a different office; and (b) Verizon‑related 2026 Federal Circuit news (e.g., Headwater Research LLC v. Verizon, E.D. Tex. 2:23‑cv‑00352, Fed. Cir. No. 26‑1884; and USPTO v. Verizon IPR appeal) — these concern other patents and do not identify 5,319,711. Do not conflate these. (JP5319711B2 PDF; Headwater notice of appeal)
• Uncertainty: I can state only that no docket linkage was found. Absence in search results is not proof of absence from every USPTO/CAFC record.

US 5,319,711 — Wireless Device for Verifying Identification

Source of record: US5319711A on Google Patents; corroborated at uspto.report and Unified Patents Portal.

Abstract (verbatim): "A wireless communication device using a verification protocol for verifying the identification of the wireless device by a wireless network control station in the presence of eavesdroppers is disclosed. Upon receiving a call request from a wireless device claiming a particular identity, the wireless network control station sends a mask consisting of binary digits in a random order. The wireless device is expected to respond to this mask with a reply that is consistent with both the password contained in the device and the mask. Specifically, the bits of both the password and the mask are 'ANDed' and the result transmitted to the wireless network control station as the reply."

Independent claims — plain language

This patent has 6 claims total and only one independent claim: claim 1. Claims 2–6 all depend (directly or indirectly) from claim 1.

Claim 1 (the only independent claim) — covers a wireless device that answers an external identity challenge. It recites four cooperating elements:

1. First memory storing a password of multiple bits;
2. Second memory storing a mask of multiple bits (the mask arrives from the network as part of the challenge);
3. Comparison means that compares the mask bits against the password bits; and
4. Processing means that produces a multi-bit response, where each response bit is a binary one when the corresponding mask bit and password bit are both binary one.

In other words: the device performs a bit-wise logical AND of mask and password and returns the result. That AND result is the entire response. Because the network only ever learns password bits at mask-selected positions, an eavesdropper gains only partial knowledge per exchange (the security analysis in the spec quantifies this).

Dependent claims (2–6), briefly — they narrow, not broaden:

• Claim 2: a response bit is binary zero whenever the corresponding mask bit is zero (the mask-side half of the AND).
• Claim 3: a response bit is binary zero whenever the corresponding password bit is zero (the password-side half of the AND).
• Claim 4: the stored mask is expressed as addresses, each address specifying the position of a binary one in the mask (the compact "M·log₂N bits" transmission format described in the spec).
• Claim 5: the stored mask is expressed as the position of the first binary one plus differential increments to each successive one (the further-compressed "M·Log₂(M/N) bits" format; note the specification's own text for this value is inconsistently rendered as "MLog₂(M/N)").
• Claim 6: instead of a full bit-string, the processor outputs a list of addresses, each address indicating a position where both the mask bit and the corresponding password bit are one.

Technical gist / why it mattered

The patent addresses cellular/PCS cloning and subscription fraud: broadcasting a fixed identification code (the ESN/MIN-style problem) lets an eavesdropper impersonate a handset. Rather than a computationally heavy public-key exchange (which the background section criticizes), the invention uses a lightweight challenge–response: the network picks a random N-bit mask with exactly M ones, the handset ANDs it with its secret N-bit password, and returns only the overlapping ones. The specification supplies a probabilistic model (Equations 1–4) showing how, after K eavesdropped sessions, the number of password bits still unknown to the eavesdropper is L_K = N(1−[1−(M/N)]^K), and derives parameter choices (e.g., M ≈ N/(K+1); for a target success probability at K ≥ 20, M ≈ −log₂(p)/0.37) with a worked Table 1 for K = 50, p = 10⁻⁴. FIG. 2 plots the memory-vs-transmission tradeoff.

Notable prior-art references cited on the face of the patent (8): US 3,609,690; US 4,591,704; US 4,779,224; US 4,853,962; US 4,903,299; US 5,130,519; US 5,150,412; US 5,131,038. It has a substantial forward-citation trail (~211 "cited by" entries), largely in the Sipco/Ipco and Flexiworld families.

Uncertainty flags

• Assignee/legal-status lines are Google Patents' own disclaimers (they explicitly state legal status is an assumption, not a legal conclusion). The 2002 Verizon Labs record is a change of name from GTE Laboratories, not a sale.
• I could not verify a 2026 CAFC docket bearing this patent number; the only 2026 Federal Circuit material I surfaced involving Verizon concerns other patents (Headwater v. Verizon, and a separate IPR appeal), and should not be attributed to 5,319,711.

I'll run a set of targeted litigation searches for the literal identifier 5319711.

Let me run additional targeted checks against litigation-specific databases and dockets.

Bottom line

No litigation is known involving U.S. Patent No. 5,319,711. I found no district-court case, no ITC investigation, no PTAB proceeding, and no Federal Circuit appeal in which US 5,319,711 was asserted, challenged, or otherwise at issue. The patent appears to have lived and died in litigation silence, consistent with its status as an expired, never-asserted GTE/Verizon Laboratories patent.

That is a negative finding, and I flag below exactly how strong it is and what I could not check.

What I searched and what came back

One genuine, correct-number hit — but it is not litigation against the patent

A PTAB petition document (petition ID 1547246) contains the entry "5319711, June, 1994, Servi" in a prior-art reference list alongside "5295154, March, 1994, Meier et al." and "5319364, Glidewell et al." (PTACTS document).

Interpretation: US 5,319,711 was cited as prior art in an unrelated inter partes review petition (the surrounding art is cellular-telephone authentication art, e.g. the Meier et al. reference). This is a citation event, not an assertion of, or challenge to, 5,319,711. I could not resolve the specific IPR number from the fragment returned, so I state this cautiously.

False positives I deliberately excluded (do not conflate these)

These share the digit string 5319711 but have nothing to do with US 5,319,711:

• JP 5319711 B2 — Japanese patent (Dr. Optics SE; optical glass elements / automotive headlight lenses; IPC C03C/C03B/F21S), registered 2013-07-19, published 2013-10-16. Different office, different subject matter. (PDF)
• Seoul Central District Court 2016.05.25, case 2015가단5319711 — Korean civil indemnity action ("구상금"); the digits are a Korean case number, not a patent. (legalengine.co.kr)
• Eighth Circuit docket No. 23-3155 (Jeffrey Raymond v. United States) — "5319711" appears only as a CM/ECF internal docket-entry tag [5319711]. Not a patent. (Justia docket)
• Hari Govind International Ltd. — "Script Code: 5319711" is a BSE (India) stock ticker, not a patent. (BSE filing)
• Headwater Research LLC v. Verizon (E.D. Tex. 2:23-cv-00352; Fed. Cir. No. 26-1884) and the separate USPTO v. Verizon IPR appeal — Verizon-adjacent 2026 Federal Circuit activity, but concerning other patents. Not 5,319,711.

Reasoning on why an assertion case is unlikely to exist

1. Terminal expiry. Google Patents lists anticipated expiration 2012-08-19 and legal status "Expired – Lifetime"; the year-11 late surcharge and year-12 maintenance fee were paid 2005-12-08. Any assertion suit would have needed to be filed on or before that date to reach a live claim.
2. No reexamination or IPR against it appears. A patent in an NPE's hands typically shows either forward-citation clustering in litigation plus a validity challenge. Here the ~211–213 forward citations come overwhelmingly from the Sipco/Ipco and Flexiworld families — i.e., those patents cite 5,319,711 as background prior art, which is the opposite of litigation.
3. Assignee posture. GTE Laboratories → name change to Verizon Laboratories, Inc. (recorded 2002-11-21, effective 2000-06-30). This is a corporate renaming, not an assignment to a monetization entity, which is why no NPE assertion trail exists.
4. Family. EP 0584667 A1 was withdrawn; CA 2104092 C granted 2004-12-07 and expired. No counterpart office shows opposition or invalidity proceedings tied to the US patent.

Confidence and limitations (stated explicitly)

• Confidence that no litigation was found: high. Every identifier-specific search returned either nothing or the documented false positives.
• Confidence that no litigation exists: moderate, not certain. Absence from search results is not proof of absence from PACER, Docket Navigator, Lex Machina, or a sealed/terminated 1990s docket that was never digitized. Mid-1990s GTE-era declaratory-judgment actions in particular may pre-date full electronic docket coverage.
• I did not obtain a direct PACER or Docket Navigator case-list export; those are paywalled and were not reachable in this session, and I hit a tool-call ceiling before completing every planned query. I am therefore reporting "no litigation found," not "no litigation ever filed."
• Date discrepancy to flag: your instruction header states "Current Date: April 26, 2026," while the working session date is 2026-09-30. The negative litigation finding is unaffected, but any "as of" framing should use the later date.

Requested case-by-case table

If you need a defensible "no cases" certification for an IPR, DJ action, or due-diligence memo, the next step is a paid Docket Navigator or Lex Machina query on the patent number plus a PACER search across all districts, which I could not run here.

PTAB / AIA Trial Analysis — US 5,319,711 ("Wireless device for verifying identification")

Bottom line up front: there are no AIA trial proceedings on this patent. The canonical "PTAB proceedings on file" block supplied from the USPTO Open Data Portal returns an empty list, and my independent web checks (Google Patents litigation/PTAB panels, Unified Patents portal entry for US-5319711-A, and targeted searches for IPR/PGR/CBM filings naming "5319711" or "'711" in the Servi/GTE context) surfaced nothing to the contrary. Everything below is written to that reality rather than to a template.

Proceedings overview

Total AIA trial proceedings on file: 0. Breakdown: 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution denials — there is no IPR, no PGR, and no CBM to categorize. (Source of record: the structured "PTAB proceedings on file" block in this prompt, sourced from the USPTO Open Data Portal; corroborating null results via Google Patents and the Unified Patents portal entry for US-5319711-A, neither of which lists any PTAB proceeding.)

Defensive posture: this is not "the patent has survived two IPRs and is hardened," and it is also not "claims 1–5 have been canceled." It is the third, less-discussed posture: an untouched patent whose entire enforceable life has already run. Claims 1–6 are all live on paper and have never been tested at the Board — but the patent expired 2012-08-19 (anticipated expiration per Google Patents' legal-status record), and all maintenance fees through the year-12 window were paid (last recorded payment 2005-12-08, a year‑11 late payment with surcharge). A defendant receiving a demand letter today is looking at a patent that cannot support prospective injunctive relief, and whose damages tail is confined to pre-2012 conduct. The absence of PTAB activity is therefore a signal about assertion history, not about patent strength: nobody has ever bothered to challenge it, most likely because nobody has ever needed to.

Proceeding-by-proceeding detail

None to report. There is no IPR20XX-XXXXX, PGR, or CBM entry for US 5,319,711 in the ODP data, and I found no unindexed filing in web sources. Per the operating constraints, I will not invent a proceeding number, panel, or FWD to fill the template.

For completeness, here is what a non-existent proceeding section would be saying about each procedural milestone:

Strategic summary

Claim status: everything is untested, nothing is canceled. Claims 1–6 remain as issued 1994-06-07. Claim 1 (the sole independent claim) covers a wireless device with first memory for an N-bit password, second memory for an M-ones mask, comparison means, and processing means that produces a multi-bit response in which each bit is binary one when the corresponding mask bit and password bit are both one — i.e., a hardware bit-wise AND challenge–response. Claims 2 and 3 recite the two conditional-zero halves of that AND; claim 4 recites mask-as-addresses; claim 5 recites mask-as-first-position-plus-differentials; claim 6 recites address-list output. There is no IPR certificate, no disclaimer, and no reexamination certificate of record that I could locate — so nothing has been struck, and equally nothing has been confirmed. Anyone building a non-infringement or invalidity position does so without the benefit of any Board precedent construing these terms.

Estoppel landscape: empty. Because there is no § 318(a) FWD, § 315(e)(2) estoppel is unavailable against anyone. There is also no inter partes reexamination estoppel, since the patent issued from a 1992 filing and the inter partes reexam regime (applicable only to applications filed on or after 1999-11-29) never applied to it. Practically, this means a defendant today faces zero prior-art restrictions arising from any prior proceeding — the full universe of patents, printed publications, and (in district court) systems prior art is available. The only realistic limit is § 315(b): a defendant served with a complaint more than one year ago is time-barred from filing an IPR, though that is academic here. I note one unverified gap: I could not confirm the nonexistence of an old ex parte reexamination (90/xxx,xxx) on this patent, since ex parte reexams are not part of the AIA trial ODP block and my searches returned nothing. If you are relying on a clean prosecution-history estoppel theory, pull the file wrapper via USPTO Patent Public Search / Patent Center directly.

Pattern signals: none of the usual ones. No repeat petitioner, no defensive aggregator (Unified Patents, RPX, etc.), no PTAB appeal activity by the patent owner — because there has never been a proceeding to appeal. The ~211 forward citations drive entirely from later, unrelated families (Sipco/Ipco, Flexiworld, Delahuerga, Startrak), not from litigation over this patent.

Two number-collision traps — do not conflate

These keep appearing in searches for the digits "5319711" and "711" and are not this patent:

1. JP 5319711 B2 — Japanese Patent No. 5319711, granted 2013-10-16, Dr. Optics SE, directed to producing optical glass elements / automotive headlight lenses (C03C, C03B, F21S). Different office, different subject matter. PDF
2. U.S. Patent 11,176,711 — a video-coding patent challenged by Unified Patents, LLC in an IPR petition (claims 1–3, obviousness over Kim in view of H.264 and Segall). This is a different patent (issued 2021) that happens to be referred to in its petition as "the '711 patent." Do not attribute that Unified Patents filing to US 5,319,711. Unified petition

This is consistent with the caution already flagged in the patent-summary section of this analysis, and I explicitly confirm it rather than contradicting it.

Recommended next steps

If you are a defendant today (2026-09-30):

• Lead with the expiry, not with PTAB. US 5,319,711's term ran out 2012-08-19. Any infringement theory must be limited to pre-expiration acts, and § 286's six-year damages lookback means the last recoverable window closed around 2018. If a demand letter cites claims 1–6, the first question is what acts post-2012 the sender thinks are covered. There is no FWD to quote, because there is none — the strongest available citations are the on-face record (Issue date 1994-06-07; "Expired – Lifetime," anticipated expiration 2012-08-19) at US5319711A on Google Patents.
• No PTAB-based defense exists to inherit. Because there is no institution decision and no FWD, you cannot point to a Board finding as collateral support, and you also face no estoppel — which is a net positive. Invalidity work is unconstrained: the eight references on the face of the patent (US 3,609,690; US 4,591,704; US 4,779,224; US 4,853,962; US 4,903,299; US 5,130,519; US 5,150,412; US 5,131,038) are all fair game, and so is anything else, including the well-known contemporaneous challenge–response and maskable-ID art.
• Do not file an IPR reflexively. An IPR against an expired patent is generally pointless for commercial purposes: the patent cannot be enforced prospectively, claims cannot be amended in a way that yields new coverage, and the Board will still construe claims for the (closed) damages window. If a plaintiff is somehow pressing pre-2012 damages, invalidity is more efficiently litigated in district court, where § 282's presumption and the full prior-art field apply and where an expired-patent damages case is likely to be dismissed or resolved early. If you nonetheless need the PTAB route, budget from the § 314(b) three-month institution clock and remember the § 316(a)(11) statutory one-year trial deadline from institution.
• CBM is unavailable regardless. Even setting aside that the transitional CBM program sunset on 2020-09-16, this patent is directed to authentication of a wireless device — not a "financial product or service" — and would fail the Alice-era "technological invention" carve-out analysis without straining.

If you are doing diligence / portfolio work:

• The absence of any AIA trial is itself consistent with the patent's practical history: filed 1992-08-19, granted 1994-06-07, expired 2012-08-19, with a GTE Laboratories → Verizon Laboratories change of name recorded 2002-11-21 (effective 2000-06-30) — note this is a renamification, not an assignment or sale, and Google's legal-status field is expressly an assumption, not a legal conclusion.
• The foreign family is closed out: EP 0584667 A1 was withdrawn (published 1994-03-02) and CA 2104092 C issued 2004-12-07 and has expired. Only the US case ever reached enforcement-grade status.
• If you need definitive confirmation of the negative, the authoritative check is the USPTO PTAB End-to-End system (PTAB E2E) and the USPTO PTAB Decisions page, searching by patent number 5,319,711 and application number 07/932,133. Nothing in the record I can reach contradicts "zero proceedings."

Uncertainty flags (per operating rules):

• I can state only that no AIA trial proceeding was found. Absence in the ODP block plus absence in search results is strong but not identical to a certified empty docket.
• I could not verify whether an ex parte reexamination (a pre-AIA, non-trial mechanism outside the ODP AIA block) ever issued for this patent. Treat "no reexamination certificate" as unconfirmed rather than established.
• No judge panels, petition grounds, institution decisions, FWDs, settlement terms, or CAFC docket numbers are reported above because none exist — not because they were hard to find. I have deliberately left those fields empty rather than speculating.

I'll verify the assignment records against multiple sources before reconstructing the chain.

Now let me check the assignment records, litigation history, and any asserter-directory entries.

Let me pin down the exact reel/frame records and check for any additional recordings.

Assignment & Ownership Chain — US 5,319,711

Sourcing note first. The USPTO Assignment Center (assignmentcenter.uspto.gov) is an interactive search UI and I could not execute a live query against it in this session. The assignment data below is reconstructed from (a) the Google Patents legal-events table on the authoritative patent page, which preserves the original record's reel/frame and assignor fields, and (b) a Plainsite mirror of the recorded assignment documents, which adds the execution date, recording date, and assignee address for the post-2000 record. Every reel/frame below is quoted as found; where two sources disagree I flag it rather than reconciling it. The correspondent-of-record field was not retrievable from either source — see signal 3.

Inventors

Pattern check — "all inventors departing within 12 months of filing": not applicable and not present. This is a single-inventor patent, and there is no record evidence of the inventor's departure. A same‑day assignment to the employer is the opposite of the fire-sale precursor you asked me to watch for; it is the routine case.

Uncertainty flag: I could not verify Servi's post‑2000 tenure at the renamed entity (Verizon Laboratories, Inc.) from the sources reachable here. I decline to assert it either way.

Original assignee

GTE Laboratories Incorporated, a Delaware corporation — named on the face of the patent and the assignee of the 1992 assignment.

• Primary line of business: the corporate research and development subsidiary of GTE Corporation, i.e. the central R&D lab for GTE's telephone operating companies and its cellular/PCS ambitions. This is consistent with the patent's subject matter: a wireless-network authentication protocol intended for a carrier's own infrastructure, not a standalone product.
• Did they ship a product embodying the claims? No evidence of one, and none would be expected. The patent claims a wireless device (handset-side AND-mask logic) used inside a carrier's authentication exchange. GTE Labs was a research organization; the commercial embodiment would have been deployed inside GTE's cellular network and handsets, not sold as a GTE Labs product. I found no product, no product literature, and no licensing program tied to this patent.
• Current status: operating, via name change only. GTE Laboratories Incorporated was not dissolved, sold, or spun out. Effective 2000‑06‑30, coincident with the completion of the Bell Atlantic / GTE merger (Bell Atlantic Corporation d/b/a Verizon Communications filed an 8‑K reporting the merger consummated 2000‑06‑30), the entity was renamed Verizon Laboratories, Inc. The parent, Verizon Communications, remains an operating NYSE-listed carrier.

Assignment timeline

Three candidate records. The first two are firm; the third is flagged as a probable duplicate recording of the same 2000 conveyance, and I will not present it as an independent transfer.

1. Original employee assignment

1992‑08‑19 (executed) / recorded 1992‑08‑19 — Reel 006226 / 0961

• Conveyance: Assignment of assignors' interest ("ASSIGNMENT OF ASSIGNORS INTEREST")
• Assignor: SERVI, LESLIE D.
• Assignee: GTE LABORATORIES INCORPORATED, a Corp. of DE
• Correspondent: not present in the record text I could retrieve. No correspondent field was exposed by Google Patents' legal-events rendering.
• Context: Initial employee invention assignment; executed on the same day the application was filed. Ordinary corporate ownership — no acquisition, no third party.

2. Change of name (the only post‑issuance record)

2000‑06‑30 (executed) / recorded 2002‑11‑21 — Reel 013258 / 0122

• Conveyance: Change of Name
• Assignor: GTE LABORATORIES INCORPORATED
• Assignee: VERIZON LABORATORIES, INC. (Massachusetts)
• Correspondent: not retrievable from the sources I could reach.
• Context: Internal reorg / change of name only. Corroborating detail from the Plainsite mirror of the recorded document: assignee address 40 Sylvan Road, Waltham, MA 02451 — i.e. the former GTE Labs research campus, now Verizon's, not a registered-agent or virtual-office address. No consideration, no sale, no change in beneficial ownership.

3. Flagged discrepancy — possible earlier recording of the same change of name

2000‑06‑30 (executed) / recorded 2001‑01‑19 — Patent Assignment 12123 / 500

• Conveyance: Change Of Name
• Assignor: GTE Laboratories Inc. · Assignee: Verizon Laboratories, Inc.
• Context: Same conveyance type, same execution date, same parties as entry 2 — but a different reel/frame and a recording date roughly 22 months earlier.

This is a genuine contradiction between my sources and I am flagging it explicitly rather than silently picking one. Two readings are plausible: (i) the change of name was recorded twice (an initial bulk recording in January 2001, then a re-recording in November 2002 under a new reel), or (ii) the Plainsite record 12123/500 belongs to a different patent handled in the same bulk transaction and was mis-linked in the mirror. I cannot resolve which from the material available. Either way, the substantive conveyance is the same and does not affect the ownership conclusion.

What is not in the record

Notably absent, and this matters for the verdict:

• No security agreement, collateral assignment, or securitization recording.
• No license, exclusive license, or release recorded against the patent.
• No merger recording (the GTE/Bell Atlantic merger was a stock merger; the lab entity survived as a renamed subsidiary rather than being merged away).
• No assignment recorded after 2002. The last recorded assignee of US 5,319,711 is Verizon Laboratories, Inc., and the patent expired 2012‑08‑19 (maintenance fees paid through the 12‑year window; anticipated expiration recorded).

Timeline diagram

timeline
    title Ownership of US 5319711
    1992 : Application filed August 19
         : Servi assigns to GTE Laboratories
    1994 : Patent issued June 7
    2000 : GTE merged into Bell Atlantic
         : GTE Labs renamed Verizon Laboratories
    2001 : Change of name recorded reel 012123
    2002 : Change of name recorded reel 013258
    2012 : Patent expired August 19

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT.
There is no assignment to any LLC/Inc. bearing an "IP / Patents / Licensing / Holdings / Ventures" suffix. The last recorded assignee is Verizon Laboratories, Inc., a Massachusetts corporation at 40 Sylvan Road, Waltham, MA (Plainsite mirror of the change-of-name record) — a research-campus address, not a registered-agent service. Only one substantive post-issuance record exists (reel 013258/0122, plus the flagged 012123/500 duplicate), so there is no shell-structured chain to speak of.

2. Known asserter in the chain — NOT PRESENT.
Neither GTE Laboratories Incorporated nor Verizon Laboratories, Inc. appears on any of the named NPE rosters (Acacia, Marathon Patent Group, Intellectual Ventures, IPNav, Wi‑LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio IP Ventures, MPHJ, Lumen View, Round Rock Research, Document Generation Corp, or Spangenberg entities). The Unified Patents portal entry for US‑5319711‑A surfaces forward citations only — no ownership change, no assertion record. No Unified Patents or RPX assertion-list entry for this patent was found.

3. Repeat correspondent across the chain — UNCLEAR / NOT DETERMINABLE.
This is the one place where I have to report a gap rather than a finding. The correspondent-of-record field was not exposed by either source I could reach, so I cannot name the attorney or firm on reel 006226/0961 or reel 013258/0122, and I cannot test for recurrence. The single indirect datapoint is that the 2001 record lists the assignee's own Waltham campus address, which is more consistent with recording by the company's internal IP department than by an outside NPE-focused filing firm. Per your own instruction — the signal is recurrence, and one appearance is not a finding — this must be left as unclear rather than scored. I would not treat the chain as clean on this point without a live Assignment Center lookup.

4. Cascading transfers — NOT PRESENT.
Three records at most, spanning 1992 → 2001/2002, all between the same corporate family. No chained LLCs, no transfers inside a 24‑month window to unrelated entities, no shared-address assignees. The longest gap is roughly nine years between the original assignment and the change of name.

5. Pre-litigation transfer — NOT PRESENT.
I found no infringement suit, ITU action, or Federal Circuit appeal naming US 5,319,711. There is therefore no litigation date to measure a 6‑month window against. Caution: 2026 Federal Circuit material involving Verizon exists but concerns other patents and other parties — e.g. Headwater Research LLC v. Verizon Communications Inc. (E.D. Tex. 2:23‑cv‑00352, Fed. Cir. No. 26‑1884) — and must not be attributed to this patent. Similarly, JP 5319711 B2 (Dr. Optics SE, granted 2013‑10‑16, optical glass for automotive headlights) is a different patent in a different office that merely shares the digit string.

6. Bankruptcy fire-sale — NOT PRESENT.
No Chapter 7 or Chapter 11 proceeding for GTE Laboratories or Verizon Laboratories was found. The relevant corporate event was a solvent stock merger (Bell Atlantic/GTE, consummated 2000‑06‑30 per the Bell Atlantic 8‑K), not a distressed sale.

7. Privateering — NOT PRESENT.
Privateering requires an operating company to transfer to an NPE that asserts on its behalf. Verizon Laboratories never transferred the patent out, and no third party asserts it. Nothing in SEC filings or in the RPX/Unified litigation-document corpus surfaced here ties this patent to a privateering arrangement.

8. Defensive aggregator (anti-NPE) — NOT PRESENT.
The chain does not terminate at RPX, Allied Security Trust, LOT Network, Unified Patents, or the Open Invention Network. There is no defensive-aggregation recording of any kind.

Verdict

Defensive / non-asserting — closest available fit; the taxonomy's parenthetical does not literally match, and I say so rather than force it.

Justification: the chain terminates at an operating telecommunications company, Verizon Laboratories, Inc., via a change-of-name only record (reel 013258/0122, executed 2000‑06‑30, recorded 2002‑11‑21), with the only prior record the original employee assignment to GTE Laboratories Incorporated on reel 006226/0961 (1992‑08‑19). There is not a single signal of NPE activity — no LLc transfer, no known asserter, no cascading transfers, no bankruptcy, no privateering, no pre-litigation transfer, and no assertion of the patent anywhere in the district-court or Federal Circuit material I could reach — and the patent has been expired since 2012‑08‑19, which forecloses future assertion. The caveat is definitional: the "Defensive / non-asserting" bucket is described in your rubric as a chain terminating at a defensive aggregator, and no such aggregator is involved here. What this actually is, is a plain vanilla, never-asserted, operating-company-held patent — which the rubric has no dedicated slot for. I am not choosing "Operating-company assertion" because the second element of that test fails outright: Verizon Laboratories is not suing anyone over this patent, and no product embodying the claims was identified.

Verification: search patent number 5319711 at the USPTO Assignment Center or the legacy Assignment Search; the record is also mirrored at uspto.report/patent/grant/5319711 and the Google Patents legal-events table at patents.google.com/patent/US5319711/en.

Two open items for a live-record follow-up: (i) pull the correspondent-of-record from reel 006226/0961 and reel 013258/0122 to close out signal 3; and (ii) confirm whether reel 012123/0500 (recorded 2001‑01‑19) is a duplicate recording of the same change of name or a mis-linked record from a different patent in the same bulk filing.

I'll verify the patent against USPTO-facing sources and then run down each cited reference individually.

The front-page OCR of the patent PDF shows a possible discrepancy on the first reference (reads "3,609,600 Nissman et al." while Google Patents lists US 3,609,690/Holobeam). Let me verify that and run down the remaining cited references.

Prior-Art Analysis — US 5,319,711 (Servi / GTE Laboratories)

0. Verification of the target patent

I searched specifically for the literal number 5319711 and confirmed the record against the printed front page, not just an index entry:

• US 5,319,711, "Wireless device for verifying identification," inventor Leslie D. Servi, assignee GTE Laboratories Inc., Appl. No. 07/932,133, filed Aug. 19, 1992, issued June 7, 1994, 6 claims, 2 drawing sheets. Front page confirms Int. Cl. H04L 9/32; H04L 9/00; H04K 1/02; U.S. Cl. 380/23, 380/6, 380/49, 340/825.31, 340/825.34. (Google Patents; printed PDF; uspto.report; Unified Patents)

Number-collision warning (as flagged in the earlier section): a separate document, JP 5319711 B2 (Dr. Opticus SE, optisches Glas / automotive headlight lens method, granted 2013‑10‑16), shares the digits. It is unrelated art in a different office and classification (C03C/C03B/F21S) and is not part of this analysis.

1. The eight references cited on the face of US 5,319,711

The "References Cited" list on the printed front page is the authoritative source. I reproduce it literally, including an OCR/listing discrepancy on the first entry.

Discrepancy to hold open (do not auto-correct): Google's citation index links entry #1 to US 3,609,690 ("Secure personnel access control system," Holobeam), while the printed front page of the '711 patent reads "3,609,600 … Nissman et al." I could not retrieve the full front matter of either 3,609,690 or 3,609,600 to resolve which is correct. Both readings are presented so nothing is silently "fixed."

2. § 102 framework that actually applies here

US 5,319,711 was filed 1992‑08‑19, so pre-AIA 35 U.S.C. § 102 governs (post-AIA first-inventor-to-file did not apply until applications filed on/after 2013‑03‑16). That splits the eight references into two buckets:

• Post‑1991 references — § 102(b) statutory bars (published >1 year before filing): #1 (1971), #2 (1986), #3 (1988), #4 (1989), #5 (1990‑02‑20). These can be § 102 anticipatory art or § 103 art unqualified.
• Within one year of filing — no § 102(b) bar; must qualify under § 102(a) or § 102(e): #6 and #7 (both published 1992‑07‑14) and #8 (published 1992‑09‑22, i.e., after the '711 filing date — it can only be § 102(e) art, as a U.S. patent granted on an application filed before Aug. 19, 1992, or § 102(a) if shown to predate conception/reduction to practice).

Important: a dependent claim carries every limitation of the claim it depends from. Because claims 2–6 all depend from claim 1, a reference that cannot anticipate claim 1 cannot anticipate claims 2–6 standing alone. The mappings below therefore test each reference against claim 1's four elements (E1 password memory; E2 mask memory holding a mask received with the external identification request; E3 bit-by-bit comparison means; E4 response in which each bit is one iff the corresponding mask bit and password bit are one — i.e., the bit-wise AND).

3. Reference-by-reference § 102 assessment

#3 — US 4,779,224 (Moseley), "Identity verification method and apparatus," 1985‑03‑12 / 1988‑10‑18 — § 102(b) art. Strongest single reference.
Discloses the full architectural loop: a base unit generates a random number X, transmits it to the remote unit; the remote computes Y = f(K, X) using a stored constant K; the result is returned and compared against the base's own computation, with access gated on the match. (Google; PDF; uspto.report)

• Maps to E1 (stored secret K ≈ password), E2 (challenge X ≈ mask), E4-in-substance (response = f(mask, secret)).
• Gap defeating anticipation: the reference discloses an unspecified "predetermined mathematical algorithm," never a bit-wise AND of corresponding mask and password bits where non-selected response bits are zero. No disclosure of mask density (exactly M ones of N), no password-bit-structure alignment.
• Verdict: potentially anticipates claims 1–6 only if one improperly equates f(K,X) with the AND — it does not disclose it. Best used as § 103 primary reference. It is, however, the closest § 102(a) "same scheme" art for the claim-1 preamble.

#5 — US 4,903,299 (Lee et al. / Dallas Semiconductor), "ID protected memory with a maskable ID template," 1988‑06‑28 / 1990‑02‑20 — § 102(b) art. Most structurally on-point.
The title itself describes an ID template held in protected memory with a mask that gates which ID bits are exposed. That is the closest single reference to the E1 + E2 + "masked readout of stored ID bits" combination, and it predates the '711 filing by more than a year.

• Maps to E1 (stored ID = password analog), E2 (mask), and arguably a mask-gated output resembling E4.
• Gaps: I could not retrieve the full text (tool budget exhausted), so I cannot confirm (a) whether the gating is a per-corresponding-bit AND rather than a block/sector mask, (b) whether any response is generated in reply to an external identification request from a network station, or (c) any wireless/telephony context.
• Verdict: flag as the top-priority § 102 candidate for claims 1, 2, 3 and possibly 4, pending full-text verification. Treat as high-relevance/high-uncertainty.

#7 — US 5,131,038 (Puhl et al., Motorola), "Portable authentification system," 1990‑11‑07 / 1992‑07‑14 — § 102(e) art only.
A portable unit authenticated against a fixed unit; typical challenge-response over a wireless link with a stored secret in the portable.

• Maps to E1, E2 (challenge), and a response-computing processor — but the operative transformation is a cryptographic algorithm, not the claimed corresponding-bit AND.
• Verdict: § 102(e) candidate; realistically § 103 art. Cannot anticipate claim 1 on the available record.

#8 — US 5,150,412 (Maru, NEC), "Security module for radio telephone," 1990‑04‑28 / 1992‑09‑22 — § 102(e) only (published after the '711 filing date).
A security module for authenticating a radio telephone (stored key + response computation to a base-station challenge).

• Maps to E1 and E4-in-substance at the architecture level; nothing indicates mask density or an AND operation.
• Verdict: § 103 art; useful for the "authentication module in a radio telephone" environment.

#6 — US 5,130,519 (Bush et al.), "Portable pin card," 1990‑01‑16 / 1992‑07‑14 — § 102(e) only.
PIN-carrying portable card with stored secret (PIN) and comparison/verification logic.

• Maps to E1 and E3 (comparison) only. No externally transmitted mask; no AND-generated response.
• Verdict: § 103 art; potentially anticipating nothing on its own.

#1 — US 3,609,690 (Holobeam) / "3,609,600 … Nissman et al.," 1969‑10‑17 / 1971‑09‑28 — § 102(b) art.
Card reader + keyboard; the card carries a scrambled binary code and the holder keys a privately known number; the two 24-bit strings are shifted bit-by-bit into a comparator (element 90) producing go/no-go. (Google; PDF)

• Maps to E3 (bit-by-bit comparator of two binary strings) and loosely to E1 (stored code).
• Gaps: the "mask" is a fixed scramble code board wired into the reader — it is not a value transmitted to the device as part of an external identification request, and there is no response output at all (the result is only an internal go/no-go).
• Verdict: does not anticipate any of claims 1–6; relevant to E3 as § 103 art.

#2 — US 4,591,704 (Sherwood et al., Engineered Systems), "Data scrambling system and method," 1983‑04‑18 / 1986‑05‑27 — § 102(b) art.
A random number generator combined with "microprocessor mask storage" builds a bit-transposition pattern used to encode/decode card data; the same mask is stored at the issuing and reading ends. (Google)

• Maps to E2 only in the narrow sense that a "mask" is stored in a memory — but the mask is a permutation/relocation pattern for magnetic-stripe fields, fixed at card issuance, not an external challenge, and never ANDed with a password.
• Verdict: does not anticipate claims 1–6; marginal § 103 art that may be cited for the term "mask" in memory.

#4 — US 4,853,962 (Brockman, Universal Computer Consulting), "Encryption system," 1987‑12‑07 / 1989‑08‑01 — § 102(b) art.
An encryption/decryption key-sequence system (classified 380/44 on the '711 front page). It is confidentiality art, not challenge-response identification art.

• Verdict: does not anticipate claims 1–6; at most background § 103 art on cryptographic masking.

4. Bottom line on anticipation

No single reference among the eight cited anticipates claim 1 on the record available. Anticipation of claim 1 requires one reference disclosing all four elements — most critically a multi-bit mask received with the external identification request whose bits are ANDed corresponding-bit-wise with the stored password to form the entire response. Each reference misses at least one element:

• US 4,779,224 and US 5,131,038 disclose challenge-response with a stored secret, but the transformation is a general algorithm/keyed function, not the claimed AND.
• US 4,903,299 discloses a maskable ID template (the closest structural hit for E1/E2) but I could not verify it discloses a corresponding-bit AND response to a remote request.
• US 3,609,690 and US 4,591,704 use "mask"/comparison concepts in non-analogous ways (fixed scramble board; bit transposition).
• US 4,853,962, US 5,130,519 and US 5,150,412 supply only isolated elements.

Because claims 2–6 all depend from claim 1, none of them can be anticipated by these references either. The realistic posture of this art set is § 103 (e.g., US 4,779,224 in view of US 4,903,299, or US 4,779,224 in view of US 3,609,690). That the '711 patent issued with all six claims intact is consistent (though not proof) that the examiner did not find a single-reference anticipation. This is an inference, not a documented fact.

5. Secondary art surfaced by the family (worth adding to a search report)

Two references appear in the family-cited list (i.e., cited against the EP/CA counterparts), and one "similar document" is notable:

• US H510 H (Statutory Invention Registration; 1983‑02‑24 / 1988‑08‑02) — "Automatic authentication for voice transmissions," U.S. Air Force.
• US 4,964,163 (Motorola; 1988‑04‑04 / 1990‑10‑16) — "Method and apparatus for controlling access to a communication system." Given assignee and title, this is a plausible additional § 102(b) challenge-response-in-a-communication-system reference and should be pulled in full.
• US 5,279,904 (published 1994‑01‑11) — "Method of verifying identification," listed as a similar document. Note its publication post-dates the '711 filing; treat it as related family art rather than § 102 prior art absent an earlier effective date.

6. Uncertainty flags (explicit)

1. First cited reference is ambiguous: "US 3,609,690 / Holobeam / Nissman et al." vs. front-page "3,609,600 … Nissman et al." I did not resolve this.
2. Full texts not retrieved for #4, #5, #6, #7, #8 due to search-step limits. Their descriptions above rest on title, classification, front-page inventor/assignee data, and general knowledge of those patents — treat the substantive § 102 conclusions for #5 especially as provisional and verify against the full specifications before relying on them.
3. Filing dates shown as "priority" dates for #6–#8 are the dates in the Google Patents citation table; the underlying U.S. application filing dates (needed for a precise § 102(e) date) were not independently confirmed.
4. Nothing here is a legal conclusion; Google Patents itself disclaims that its status/assignee fields are legal conclusions.

I'll ground this analysis in the actual cited references. Let me pull the substance of the key prior-art documents on the face of US 5,319,711.

Now the remaining cited references — the authentication/cellular ones are most relevant to the motivation-to-combine analysis.

Obviousness Analysis — U.S. 5,319,711 (Servi), under 35 U.S.C. § 103

Note on record inconsistencies (flagged as instructed):

• The prior sections were generated with a fetch/current date of 2026‑09‑30; this task states a current date of April 26, 2026. I treat the legal analysis as date‑insensitive (the patent expired 2012‑08‑19) and flag the discrepancy rather than resolve it.
• The prior summary already flagged that the specification renders the differential‑mask bit count as "M·Log₂(M/N)" — internally inconsistent with the surrounding text. I do not correct it below.
• Where I could not verify a reference's disclosure text in this session, I say so explicitly rather than assume content.

1. Framework and the hypothetical person of ordinary skill

Governing standard. Because the application was filed 1992‑08‑19, pre‑AIA § 103 applies. The controlling inquiry remains Graham v. John Deere, 383 U.S. 1 (1966), as refined by KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007): scope/content of the prior art, differences between prior art and claims, level of ordinary skill, and objective evidence of non‑obviousness. Under KSR, a combination is obvious where it "was a combination of familiar elements according to known methods [yielding] predictable results," or where it merely pursues "a known option" from "a finite number of identified, predictable solutions."

POSITA (proposed). A B.S.‑level electrical engineer or computer scientist with ~2–3 years' experience in wireless telephony or access‑control systems, familiar with (i) cellular/PCS call setup and the ESN/MIN‑style identification problem, (ii) challenge–response authentication, and (iii) elementary bitwise logic and error‑correcting coding. No advanced cryptography training required — the patent itself disclaims the cryptography route as "substantial computation."

Important scoping point. The § 103 analysis must test the claims, not the specification. The elaborate probabilistic model (Equations 1–4, Table 1, FIG. 2 — the L_K recurrence, M ≈ −log₂(p)/0.37, etc.) is not claimed. None of claims 1–6 recites an eavesdropper‑success probability, a parameter relationship, or a value of N, M, or K. So the "inventive contribution" for § 103 purposes reduces to: a wireless device that stores a secret password and a received mask and returns their bitwise AND (claims 1–3), plus compact mask/response encodings (claims 4–6). This is the correct frame, and it materially weakens the non‑obviousness position.

2. What each cited reference teaches (grounded)

Claim 1 decomposes into: (a) wireless device responding to an external identity request; (b) first memory storing a multi‑bit password; (c) second memory storing a multi‑bit mask; (d) comparison means comparing mask bits to password bits; (e) processing means emitting a multi‑bit response with a 1 where mask∧password = 1.

Critical observation for the analysis: no single cited reference discloses the literal bitwise AND of mask and password as the response. The two closest architectures — US 5,150,412 and US 4,779,224 — both compute a cryptographic/one‑way function F(R,KEY) or f(K,X), not a bitmask AND. This is why the examiner issued the patent, and it is the pivot on which any § 103 rejection must turn: the case is a combination case, and the motivation to substitute the AND must be articulated.

3. The primary § 103 combination: US 5,150,412 (NEC) + US 4,903,299 (Dallas Semiconductor)

This is the strongest, most field‑proximate combination.

The combination. US 5,150,412 supplies everything except the mask and the AND: a wireless radio telephone (a), a stored secret (b) in a memory of the device, a network‑generated random challenge transmitted to the device (c), a device‑side comparator/processor (d)–(e), and an explicit anti‑eavesdropping purpose in exactly the cellular context the '711 patent addresses. US 4,903,299 supplies the missing mask‑based challenge: a transmitted mask word that selects a subset of a stored secret template, against which only the unmasked bits are compared.

Motivation to combine (articulated, not conclusory):

1. Same field, same problem, same solution architecture. Both references address identifying a device to a verifier over an insecure link; US 5,150,412 is specifically a radio telephone security module and US 4,903,299's preferred embodiment uses "a wireless data link" to remote units (its text: "a wireless data link is used in the preferred embodiment"). A POSITA designing cellular authentication in 1992 would naturally look to both.
2. Predictable result, no change in principle of operation. Substituting a mask‑selected bit comparison for a full‑secret one‑way function does not alter how either system operates — both remain "network challenges, device answers from secret, network compares." KSR, 550 U.S. at 417 (predictable variation of known elements).
3. Known design incentive — the patent's own premise. The '711 specification criticizes public‑key methods because "such methods require substantial computation." US 5,150,412's one‑way function F(R,KEY) likewise requires computation. A POSITA seeking a lower‑compute challenge–response for a low‑cost handset had a concrete reason to replace the cryptographic combiner with the cheapest available combiner — a bitwise logical operation. This is a classic KSR "design incentive" rationale.
4. Finite, identified, predictable solutions. The elementary ways to combine two equal‑length bit vectors in a challenge–response are: AND, OR, XOR, and equality‑compare. Selecting AND is the selection of a known option with a known, predictable output table — not an unpredictable "invention." KSR, 550 U.S. at 421 ("a finite number of identified, predictable solutions").

Why AND specifically is not a leap. The '711 device's response reveals the secret only at mask‑selected positions — which is precisely the information‑leak profile that US 4,903,299's masked‑bit comparison already exhibits (only the unmasked bits of the template are exposed). The AND is, functionally, the response‑generating counterpart of Dallas Semiconductor's masked comparison. The advance is one of formatting a known masked comparison as an ANDed response vector, a matter of ordinary engineering.

4. Alternative / reinforcing primary combination: US 4,779,224 (Moseley) + US 4,903,299

Use this if the NEC reference's § 102(e) status is contested (see § 7 below).

• US 4,779,224 teaches the full random‑challenge → stored‑constant → compute → return → compare loop in an identity‑verification system, and expressly makes the algorithm a predetermined mathematical function stored at both ends — i.e., a design choice, not a fixed requirement.
• US 4,903,299 adds the mask.
• Motivation: both are identity‑verification systems protecting access against impersonation; combining a mask‑based challenge with a stored‑secret response is the straightforward union of two known verification primitives, with predictable results. In re Mouttet, 686 F.3d 1322 (Fed. Cir. 2012) ("no requirement of actual physical substitution of elements").

Reinforcing reference: US 5,131,038 (Motorola). Motorola teaches a wireless, portable identity transceiver that answers an external identity request and whose response is selected by information in that request. That is a direct teaching of claim‑element (a) in a portable wireless device, and it further supports the motivation to move the Moseley/NEC scheme into a wireless handset. (Motorola's reference also frames the art as motivated by "identity authentication" needs — same problem statement.)

5. Dependent claims 2–6

6. Objective (secondary) considerations — Graham factor 4

• No commercial‑success or long‑felt‑need record is in this file. The patent expired (anticipated expiration 2012‑08‑19; year‑11 surcharge and year‑12 fee paid 2005‑12‑08), the EP counterpart EP 0584667 A1 was withdrawn, and the CA counterpart CA 2104092 C expired. Nothing in the record establishes a nexus between any objective indicium and the claimed AND‑device.
• The most fêted part of the disclosure is unclaimed. The probabilistic parameterization (Eqs. 1–4; Table 1 for K = 50, p = 10⁻⁴; FIG. 2) is absent from all six claims, so it cannot supply non‑obviousness for the claims as written. This is the single biggest weakness in any non‑obviousness defense.
• Silence cuts against the patentee under KSR. No teaching‑away evidence appears in the cited art; the "public‑key is too costly" passage in the '711 background is an admission that the art recognized a need for lightweight verification, which is a motivation‑to‑combine fact, not a teaching away.

7. Counterarguments, weaknesses, and uncertainties (stated explicitly)

1. Blocking/qualifying‑date issue — must be checked before asserting the NEC combination. US 5,150,412 issued 1992‑09‑22, after the '711 filing date of 1992‑08‑19. It is therefore not § 102(a)/(b) art by issue date; it can only be prior art via pre‑AIA § 102(e) as a granted U.S. patent whose application was filed before the applicant's date. Its listed priority is 1990‑04‑28, so a 1991 U.S. filing is plausible and § 102(e) likely applies — but I did not verify its U.S. filing date in this session, and I flag this as unconfirmed. The same analysis applies to US 5,131,038 and US 5,130,519 (both issued 1992‑07‑14, i.e., before the filing date, so they are § 102(a)/(e) art). If US 5,150,412's date fails, pivot to the Moseley + Dallas Semiconductor combination (§ 4), which is date‑safe.
2. No reference literally discloses the AND. All of the closest architectures (US 5,150,412, US 4,779,224) use one‑way/cryptographic functions, not bitwise AND. A rejection must therefore rest on the AND being an obvious combining‑function choice — a defensible but not automatic position under KSR. The patentee's best rebuttal is that the references teach away from a function that leaks secret bits (the AND leaks M bits per session by construction); the counter is that US 4,903,299's masked comparison is itself a deliberate partial‑disclosure scheme, so partial disclosure was an accepted design posture.
3. US 4,903,299's purpose differs. Its masked read is a polling/discovery mechanism to identify which remote units are in range — not authentication of a secret against an impersonator. A rejection combining it with a radio‑telephone authentication scheme must articulate the motivation to transplant the mask into an authentication role. That articulation is available (§ 3, points 1–2) but must be made expressly; a bare "both relate to identification" assertion would be vulnerable to a KSR "conclusory" attack, as seen in the PTAB practice reflected in the record (e.g., the Gass/Martin applicant‑response arguments surfaced in search).
4. Unverified references. I could not retrieve the full text of US 3,609,690, US 4,591,704, US 4,964,163, US H510, or US 5,130,519 in this session. They are characterized above only at the level of their titles/fields; any rejection relying on them for an element (as opposed to background) should be re‑verified against the actual documents.
5. § 112 / § 101 note (adjacent, not § 103). The claims use "means for" language (comparison means, processing means), implicating § 112(f), and the core is a bitwise AND — arguably a mathematical operation. Neither point defeats a § 103 analysis, but both bear on claim scope and validity generally, and the functional claiming broadens the claims in a way that widens the prior‑art exposure.

8. Bottom line

• Claim 1 would likely be held obvious over US 5,150,412 in view of US 4,903,299 (radio‑telephone challenge–response with stored secret + transmitted mask selecting stored template bits), with US 4,779,224 and US 5,131,038 as reinforcing substitutes, motivated by (i) identical field and problem (wireless identity fraud), (ii) the art‑recognized need for low‑compute verification, and (iii) AND being one of a finite set of predictable bit‑combining options. KSR, 550 U.S. at 417, 421.
• Claims 2 and 3 are obvious as tautological halves of the AND truth table.
• Claims 4 and 6 are obvious as routine position/address encoding of a sparse mask and its response, supported by US 4,903,299 and US 4,853,962.
• Claim 5 is the weak point of the rejection: the differential‑increment mask format is a well‑known delta‑encoding technique, but I found no cited reference squarely teaching it, so a § 103 rejection of claim 5 on the cited art along would rest on "routine data compression" general knowledge and should be supported by an additional reference or an expert declaration on 1992 encoding practice. This is the claim on which the patent is most defensible on the cited record.
• The probabilistic/mathematical contributions that make the patent look inventive are entirely unclaimed, and therefore cannot rescue the claims under § 103.

Confidence: High on the claim 2–4 and 6 analysis and on the field/problematique motivation; medium on claim 1 (depends on how persuasively the AND‑as‑obvious‑combiner rationale is presented and on the § 102(e) date of US 5,150,412); low on claim 5 based solely on the eight references cited on the face of the patent.