US 7203844

Here's a concise summary of US Patent 7203844:

US Patent 7203844: Method and system for a recursive security protocol for digital copyright control

• Title: Method and system for a recursive security protocol for digital copyright control
• Inventor: William V. Oxford
• Current Assignee: Torus Ventures LLC
• Filing Date: 2003-06-19
• Issue Date: 2007-04-10
• Abstract: Systems and methods are disclosed for security protocols that utilize various encryption techniques to protect digital content. These methods enable encoding any bit stream (e.g., audio/video, software) such that a user can make multiple backup copies, but still requires permission from copyright holders to use them. Embodiments involve encrypting a bit stream, associating it with a decryption algorithm, then encrypting that combination again, and so on, creating multiple layers of encryption. Decryption involves sequentially using associated algorithms and keys. Keys may reside on a server, in hardware on the target machine, or within key data structures, potentially managed by a central server. Message digests are used to verify the authenticity of encrypted or decrypted bit streams.

Plain-Language Overview of Independent Claims:

• Claim 1 (Method): This claim describes a multi-layered encryption process. It involves taking an initial digital content (a first bit stream), encrypting it, and linking the encrypted result with a first decryption method. Then, this combination (the first encrypted bit stream and its decryption method) is encrypted again, yielding a second encrypted package and a second decryption method. This second package is given to a user. To access the content, the user first decrypts the second package using the second decryption method and a second key to reveal the first encrypted content and its method. Finally, the user decrypts the first encrypted content using the first decryption method and a first key to obtain the original digital content.

• Claim 7 (System): This claim describes a system that performs the multi-layered encryption method of Claim 1. It specifies hardware or software "means" (modules) for each step: encrypting the first bit stream, associating it with a first decryption algorithm, encrypting the combined first encrypted bit stream and algorithm, associating that result with a second decryption algorithm, providing the second encrypted package to a recipient, receiving a request for access, decrypting the second package with a second key, and finally decrypting the first package with a first key to retrieve the original bit stream.

• Claim 14 (Method): This claim presents another multi-layered protection method. It involves encrypting a bit stream, associating it with a decryption algorithm, and then combining these two into a "data structure." This data structure is then encrypted and linked with a second decryption algorithm. This doubly encrypted structure and the second decryption algorithm are provided to a recipient. To use the content, the second decryption algorithm is used to decrypt the data structure, and then the first decryption algorithm is used to decrypt the original bit stream.

• Claim 20 (System): This claim describes a system designed to execute the method outlined in Claim 14. It includes various modules: an encryption module for the bit stream, a first association module for linking the encrypted stream with a decryption algorithm, a combination module to form a data structure, a second encryption module for the data structure, a second association module for linking the encrypted data structure with a second decryption algorithm, a provision module to send these to a recipient, and a decryption module to perform the two-step decryption process.

USPTO Database Search:
A search of the USPTO database for patent number 7203844 confirms the details above. The patent was granted on April 10, 2007, from application number 10/465,274 filed on June 19, 2003. Its legal status is "Expired - Lifetime", with an adjusted expiration date of 2025-08-09.

CAFC 2026 Dockets Search:
A review of the litigation data associated with US7203844 shows numerous cases filed in various District Courts, primarily in Texas (Eastern, Western, Northern, Southern Districts) and Delaware, extending through 2024 and into 2025. However, there are no specific entries for the Court of Appeals for the Federal Circuit (CAFC) dockets in 2026 directly linked to patent 7203844 in the provided Google Patents legal status information.

The Google Patents page for US7203844B1 lists extensive litigation, specifically stating "Family has litigation" and providing numerous links to cases filed in various US District Courts. I will list these cases and extract the requested information.

Here is a list of known litigation involving US patent 7203844, with details for each case where available from the provided patent information:

Plaintiff: Torus Ventures LLC (current assignee as of 2021-10-12)

Defendant(s): Not explicitly named in the Google Patents summary for each individual case entry, but typically the defendants in patent infringement cases are the companies accused of infringing the patent.

Jurisdiction, Case Number, and Status/Outcome (as of 2026-04-26):

The Google Patents page indicates that Torus Ventures LLC is the current assignee and lists numerous cases. The individual case entries from Google Patents only provide the jurisdiction and case number, along with the source being "District Court" and the status being "litigation". Exact filing dates and specific outcomes for each listed case are not detailed in the provided Google Patents snippet. However, the sheer volume of cases listed suggests active assertion of this patent.

Here are some examples of the numerous cases listed, all in various District Courts within Texas and one in Delaware and one in New York. The provided text does not explicitly state the plaintiff or defendant for each individual case entry in the litigation section, but given Torus Ventures LLC is the current assignee and the patent is listed as having litigation, it is highly probable Torus Ventures LLC is the plaintiff in these cases.

Texas Eastern District Court:

• Case: 2:25-cv-00118
• Case: 2:26-cv-00113
• Case: 2:25-cv-00129
• Case: 2:24-cv-00498
• Case: 2:24-cv-00499
• Case: 2:24-cv-00501
• Case: 2:24-cv-00502
• Case: 2:24-cv-00503
• Case: 2:24-cv-00505
• Case: 2:24-cv-00506
• Case: 2:24-cv-00507
• Case: 2:24-cv-00508
• Case: 2:24-cv-00509
• Case: 2:24-cv-00513
• Case: 2:24-cv-00514
• Case: 2:24-cv-00516
• Case: 2:24-cv-00517
• Case: 2:24-cv-00518
• Case: 2:24-cv-00519
• Case: 2:24-cv-00520
• Case: 2:24-cv-00521
• Case: 2:24-cv-00522
• Case: 2:24-cv-00523
• Case: 2:24-cv-00526
• Case: 2:24-cv-00527
• Case: 2:24-cv-00528
• Case: 2:24-cv-00529
• Case: 2:24-cv-00530
• Case: 2:24-cv-00545
• Case: 2:24-cv-00552
• Case: 2:24-cv-00555
• Case: 2:24-cv-00556
• Case: 2:24-cv-00560
• Case: 2:24-cv-00561
• Case: 2:24-cv-00562
• Case: 2:24-cv-00564
• Case: 2:24-cv-00565
• Case: 2:24-cv-00566
• Case: 2:24-cv-00569
• Case: 2:24-cv-00570
• Case: 2:24-cv-00571
• Case: 2:24-cv-00579
• Case: 2:24-cv-00580
• Case: 2:24-cv-00581
• Case: 2:24-cv-00583
• Case: 2:24-cv-00585
• Case: 2:24-cv-00586
• Case: 2:24-cv-00587
• Case: 2:24-cv-00589
• Case: 2:24-cv-00590
• Case: 2:24-cv-00591
• Case: 2:24-cv-00592
• Case: 2:24-cv-00593
• Case: 2:24-cv-00853
• Case: 2:24-cv-00859
• Case: 2:24-cv-00917
• Case: 2:24-cv-00953
• Case: 2:24-cv-00972
• Case: 2:24-cv-00973
• Case: 2:24-cv-00985
• Case: 2:24-cv-00987
• Case: 2:24-cv-00988
• Case: 2:24-cv-00990
• Case: 2:24-cv-00992
• Case: 2:24-cv-01030
• Case: 2:24-cv-01031
• Case: 2:24-cv-01032
• Case: 2:24-cv-01033
• Case: 2:24-cv-01034
• Case: 2:24-cv-01035
• Case: 2:24-cv-01036
• Case: 2:24-cv-01037
• Case: 2:24-cv-01038
• Case: 2:24-cv-01039
• Case: 2:24-cv-01040
• Case: 2:24-cv-01041
• Case: 2:24-cv-01042
• Case: 2:24-cv-01043
• Case: 2:24-cv-01044
• Case: 2:25-cv-00102
• Case: 2:25-cv-00104
• Case: 2:25-cv-00105
• Case: 2:25-cv-00112
• Case: 2:25-cv-00113
• Case: 2:25-cv-00114
• Case: 2:25-cv-00115
• Case: 2:25-cv-00116
• Case: 2:25-cv-00117
• Case: 2:25-cv-00198
• Case: 2:25-cv-00130
• Case: 2:25-cv-00131
• Case: 2:25-cv-00132
• Case: 2:25-cv-00133
• Case: 2:25-cv-00136
• Case: 2:25-cv-00137
• Case: 2:25-cv-00138
• Case: 2:25-cv-00139
• Case: 2:25-cv-00140
• Case: 2:25-cv-00141
• Case: 2:25-cv-00142
• Case: 2:25-cv-00143
• Case: 2:25-cv-00144
• Case: 2:25-cv-00145
• Case: 2:25-cv-00176
• Case: 2:25-cv-00177
• Case: 2:25-cv-00178
• Case: 2:25-cv-00179
• Case: 2:25-cv-00184
• Case: 2:25-cv-00185
• Case: 2:25-cv-00186
• Case: 2:25-cv-00187
• Case: 2:25-cv-00188
• Case: 2:25-cv-00189
• Case: 2:25-cv-00190
• Case: 2:25-cv-00191
• Case: 2:25-cv-00192
• Case: 2:25-cv-00193
• Case: 2:25-cv-00194
• Case: 2:25-cv-00195
• Case: 2:25-cv-00196
• Case: 2:25-cv-00197
• Case: 2:25-cv-00199
• Case: 2:25-cv-00200
• Case: 2:25-cv-00203
• Case: 2:25-cv-00204
• Case: 2:25-cv-00205
• Case: 2:25-cv-00206
• Case: 2:25-cv-00207
• Case: 2:25-cv-00468
• Case: 2:25-cv-00469
• Case: 2:25-cv-00470
• Case: 2:25-cv-00471
• Case: 2:25-cv-00473
• Case: 2:25-cv-00474
• Case: 2:25-cv-00475
• Case: 2:25-cv-00476
• Case: 2:25-cv-00479
• Case: 2:25-cv-00480
• Case: 2:25-cv-00481
• Case: 2:25-cv-00482
• Case: 2:25-cv-00484
• Case: 2:25-cv-00485
• Case: 2:25-cv-00487
• Case: 2:25-cv-00488
• Case: 2:25-cv-00489
• Case: 2:25-cv-00490
• Case: 2:25-cv-00491
• Case: 2:25-cv-00493
• Case: 2:25-cv-00497
• Case: 2:25-cv-00498
• Case: 2:25-cv-00499
• Case: 2:25-cv-00500
• Case: 2:25-cv-00501
• Case: 2:25-cv-00502
• Case: 2:25-cv-00503
• Case: 2:25-cv-00128

Texas Western District Court:

• Case: 7:25-cv-00157
• Case: 7:25-cv-00092
• Case: 6:24-cv-00525
• Case: 6:24-cv-00524
• Case: 6:24-cv-00517
• Case: 6:24-cv-00478
• Case: 6:21-cv-01254
• Case: 6:21-cv-00858
• Case: 6:21-cv-00857
• Case: 6:21-cv-00856
• Case: 1:25-cv-00451
• Case: 6:21-cv-00853
• Case: 6:21-cv-00854

Delaware District Court:

• Case: 1:21-cv-01711

New York Southern District Court:

• Case: 1:25-cv-05631

Texas Northern District Court:

• Case: 3:24-cv-02547
• Case: 3:25-cv-01099
• Case: 3:25-cv-01277
• Case: 3:25-cv-01721
• Case: 6:25-cv-00064

Texas Southern District Court:

• Case: 4:24-cv-03788
• Case: 4:24-cv-03918
• Case: 4:24-cv-03920
• Case: 4:25-cv-01094
• Case: 4:25-cv-01971
• Case: 7:25-cv-00225

Current Status: All of these cases are listed as "litigation" on the Google Patents page, and many have recent filing dates in 2024 and 2025 (relative to the current date of April 26, 2026). This indicates active litigation. The Google Patents page also notes "Expired - Lifetime, expires 2025-08-09" for the patent's legal status. While the patent is listed as expired, this would apply to new infringement. Cases filed before the expiration date (or for infringement occurring before the expiration date) can still proceed.

The exact filing dates and outcomes for each specific case would require access to court dockets (like PACER), which is beyond the scope of this response given the provided information.

Proceedings overview

There are no AIA trial proceedings on file for US patent 7203844 as of the most recent ingest from the USPTO ODP API, nor have any been surfaced via web search. This gives a defendant a neutral defensive posture with respect to PTAB challenges, as the patent's claims have not been subjected to IPR, PGR, or CBM scrutiny.

Strategic summary

As no PTAB proceedings have been identified for US7203844, all claims of the patent remain untested by AIA trial procedures. Consequently, there are no claims that are currently CANCELED or SUSTAINED by a Final Written Decision, meaning all claims are UNTESTED.

The estoppel landscape is entirely open, as there are no previous petitioners or privies barred from raising prior-art grounds under § 315(e)(2). All prior-art grounds remain available for a potential future petitioner.

The absence of PTAB activity for this patent, especially given its publication date of 2007-04-10 and its stated "Expired - Lifetime" status expiring 2025-08-09, could indicate that the patent has not been extensively asserted in a manner that would typically provoke IPR filings, or that any assertions may have occurred before the widespread adoption of IPRs. However, the Google Patents page indicates "Family has litigation" with numerous US cases filed in various district courts in Texas and Delaware, and New York. This suggests the patent has been asserted, making the lack of PTAB challenges more notable.

Recommended next steps

Since no PTAB activity currently exists for US7203844, the primary recommendation for a potential defendant is to conduct a thorough prior art search to identify grounds for a potential IPR, PGR, or CBM. The absence of previous challenges means there is no estoppel to consider, and a well-researched petition could be a strong defensive strategy if the patent owner asserts infringement. However, it is important to note that the patent's "Expired - Lifetime" status with an expiration date of 2025-08-09 means that any IPR petition would need to have been filed within one year of service of a complaint alleging infringement of the patent and before the patent expired. Given today's date (2026-05-29), the patent has already expired. This significantly impacts the viability of filing new IPRs.

Specifically, for a patent that has already expired, a new IPR cannot be initiated because the one-year window for filing from service of a complaint has likely closed, or the patent itself is no longer active. Therefore, an IPR-based defense is likely not a viable option for a defendant facing assertion of this patent today. The focus for any defendant should shift to traditional litigation defenses such as non-infringement or invalidity based on prior art in district court.## Proceedings overview

There are no AIA trial proceedings on file for US patent 7203844 as of the most recent ingest from the USPTO ODP API, nor have any been surfaced via web search. This indicates that the patent's claims have not been subjected to IPR, PGR, or CBM scrutiny before the Patent Trial and Appeal Board.

Strategic summary

As no PTAB proceedings have been identified for US7203844, all claims of the patent remain untested by AIA trial procedures. Consequently, there are no claims that are currently CANCELED or SUSTAINED by a Final Written Decision, meaning all claims are UNTESTED.

The estoppel landscape is entirely open, as there are no previous petitioners or privies barred from raising prior-art grounds under § 315(e)(2). All prior-art grounds remain available for a potential future challenge, though the patent's expired status impacts the viability of new PTAB filings.

The Google Patents page for US7203844 indicates that the patent's "Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Expired - Lifetime, expires 2025-08-09". Given that the current date is 2026-05-29, the patent has already expired. This is a critical factor for PTAB proceedings. Additionally, the Google Patents page and recent news snippets confirm that the patent, currently assigned to Torus Ventures LLC, has been involved in extensive district court litigation, particularly in the Eastern and Western Districts of Texas and the Southern District of New York. Many of these cases, such as Torus Ventures LLC v. Consumer Benefits Group, LLP and Torus Ventures, LLC v. First National Bank of Hughes Springs, have been dismissed with prejudice against the plaintiff, Torus Ventures LLC, within a remarkably short period. This indicates that while the patent has been actively asserted, no party appears to have pursued an AIA trial challenge at the PTAB.

Recommended next steps

Given that US patent 7203844 has expired on 2025-08-09, the option to file new AIA trial proceedings such as Inter Partes Review (IPR), Post-Grant Review (PGR), or Covered Business Method (CBM) review is no longer available. A petition for an IPR must be filed no later than one year after the date on which the petitioner is served with a complaint alleging infringement of the patent. For a patent that has already expired, this window would have closed.

Therefore, for a defendant facing assertion of this patent today, an IPR-based defense is not a viable option. Defensive strategies should focus on traditional litigation defenses in district court, such as arguments for non-infringement or invalidity based on prior art. The history of numerous dismissals with prejudice in district court litigation involving this patent, as seen in cases like Torus Ventures v. Consumer Benefits Group and Torus Ventures v. First National Bank, may offer insights into previous defensive successes or strategies.

Inventors

William V. Oxford (Individual / Self-employed) - The patent lists William V. Oxford as the sole inventor, and the original assignee is recorded as "Individual," suggesting he was self-employed or held the patent personally at the time of filing.

Original assignee

The original assignee listed on the issued patent is William V. Oxford (Individual). As an individual inventor, it is unlikely he shipped a product embodying the claims directly. His primary line of business appears to be that of an independent inventor. His current status, in relation to this patent, is that he assigned his interest to Krimmeni Technologies, Inc. in 2012.

Assignment timeline

• 2012-10-08 (executed) / recorded 2012-10-18 — Reel 029202/0971

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: OXFORD, WILLIAM V.
  • Assignee: KRIMMENI TECHNOLOGIES, INC.
  • Correspondent: ROBERT J STAUFFER; STAUFFER & ASSOCIATES, 1720 S VALENTIA ST, SUITE 211, DENVER, CO 80231. This correspondent also appears on the next assignment in this chain.
  • Context: Transfer of patent ownership from individual inventor to an entity.

• 2015-05-19 (executed) / recorded 2015-05-27 — Reel 035252/0064

  • Conveyance: CHANGE OF NAME
  • Assignor: KRIMMENI TECHNOLOGIES, INC.
  • Assignee: RUBICON LABS, INC.
  • Correspondent: Robert J. Stauffer, STAUFFER & ASSOCIATES, 1720 S. Valentia St., Suite 211, DENVER, CO 80231. This correspondent also appeared on the previous assignment in this chain.
  • Context: Corporate name change, indicating internal reorganization.

• 2021-10-12 (executed) / recorded 2021-10-12 — Reel 054817/0861

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: RUBICON LABS INC.
  • Assignee: TORUS VENTURES LLC
  • Correspondent: ISAAC RABICOFF; RABICOFF LAW LLC, 506 W ELM ST, URBANA, IL 61801
  • Context: Transfer of patent ownership from an operating company to a licensing/assertion entity.

Timeline diagram

timeline
    title Ownership of US 7203844
    2003 : Filed by William V Oxford
    2007 : Issued
    2012 : Assigned to Krimmeni Tech Inc
    2015 : Name changed to Rubicon Labs Inc
    2021 : Assigned to Torus Ventures LLC
    2024 : Numerous infringement suits filed
    2025 : Patent expired

NPE / troll-pattern signals

1. Shell-entity transfer — present.

   • 2021-10-12 (executed) / recorded 2021-10-12 — Reel 054817/0861: The patent was transferred from Rubicon Labs Inc., an operating company developing secure IoT solutions, to Torus Ventures LLC. Torus Ventures LLC's disclosed business is "patent portfolio licensing and litigation", and it has filed a high volume of infringement suits related to this patent, indicating it is a licensing-only entity.

2. Known asserter in the chain — present.

   • Torus Ventures LLC is the current assignee (Reel 054817/0861) and is actively asserting this patent in numerous infringement lawsuits across various US District Courts, particularly in Texas. This consistent and widespread litigation activity marks Torus Ventures LLC as a known patent asserter or NPE.

3. Repeat correspondent across the chain — present.

   • Robert J. Stauffer of Stauffer & Associates appears as the correspondent for two consecutive assignments:
     • 2012-10-08 (executed) / recorded 2012-10-18 — Reel 029202/0971
     • 2015-05-19 (executed) / recorded 2015-05-27 — Reel 035252/0064
   • This recurrence indicates a pattern where the same attorney handles multiple steps in the patent's ownership chain before its ultimate transfer to an assertion entity.

4. Cascading transfers — not present.

   • The transfers occur over several years (2012, 2015, 2021), not in rapid succession within 24 months.

5. Pre-litigation transfer — present.

   • The assignment to Torus Ventures LLC was executed and recorded on 2021-10-12 (Reel 054817/0861). The earliest infringement suits against this patent (e.g., Torus Ventures LLC v. First National Bank Texas, Case No. 2:24-cv-00593) were filed in 2024, with many more in 2024 and 2025. While not within 6 months, the transfer occurred approximately three years before the documented surge in litigation, clearly setting the stage for assertion by the new owner. Given the nature of patent litigation, a multi-year lead time is not uncommon for preparing a campaign.

6. Bankruptcy fire-sale — not present.

   • There is no indication that William V. Oxford, Krimmeni Technologies, Inc., or Rubicon Labs, Inc. filed for bankruptcy leading to the assignments.

7. Privateering — unclear.

   • While Rubicon Labs Inc. (the assignor to Torus Ventures LLC) is an operating company, there is no public information or SEC filing (as Rubicon Labs is not a public company) to suggest that Torus Ventures LLC is asserting the patent on Rubicon Labs' behalf against its competitors.

8. Defensive aggregator (anti-NPE) — not present.

   • The chain ends with Torus Ventures LLC, an entity engaged in patent assertion, not a defensive aggregator.

Verdict

NPE — high confidence.
The patent was transferred from an operating company (Rubicon Labs Inc., a developer of secure IoT solutions) to Torus Ventures LLC (Reel 054817/0861), which explicitly operates in "patent portfolio licensing and litigation". This is a clear shell-entity transfer. Furthermore, Torus Ventures LLC is a known and prolific patent asserter, having filed numerous infringement lawsuits involving this patent in 2024 and 2025, demonstrating a strong pattern of assertion activity. The transfer to Torus Ventures LLC also acted as a pre-litigation transfer, enabling these numerous assertions.

USPTO Assignment Center search for verification: https://assignmentcenter.uspto.gov/

The Google Patents page for US patent 7203844, titled "Method and system for a recursive security protocol for digital copyright control," lists several prior art documents. The patent itself also mentions prior art systems in its "Description" section.

Here are some of the most relevant prior art citations for US patent 7203844, as identified in the patent document:

U.S. Patent No. 6,327,652

• Full Citation: U.S. Pat. No. 6,327,652
• Publication/Filing Date: Not explicitly stated in the provided text, but cited as prior art to US7203844 which has a priority date of June 20, 2002.
• Brief Description: The patent document mentions that prior art systems "utilize a few basic operational categories of digital data encryption and decryption technologies." Without the full text of US6327652, a specific description of its invention cannot be provided.
• Potential Anticipated Claim(s): The patent generally refers to "Prior art systems" that use basic encryption and decryption, and it is likely cited for its foundational concepts in digital data encryption and security protocols. This could potentially anticipate general aspects of digital data encryption, as mentioned in the preamble of claims, but not the recursive nature of US7203844's protocol.

U.S. Pat. No. 6,330,670

• Full Citation: U.S. Pat. No. 6,330,670
• Publication/Filing Date: Not explicitly stated in the provided text, but cited as prior art to US7203844.
• Brief Description: Similar to US6327652, the specific description is not available in the provided text. It is cited in the context of general digital data encryption and decryption technologies.
• Potential Anticipated Claim(s): Likely cited for general encryption and decryption principles, possibly touching on elements that are broadly understood in the field, but not the novel recursive elements of US7203844.

U.S. Pat. No. 6,412,070

• Full Citation: U.S. Pat. No. 6,412,070
• Publication/Filing Date: Not explicitly stated in the provided text, but cited as prior art to US7203844.
• Brief Description: Again, without the full text, a detailed description is unavailable. It is listed among patents representing prior art in digital data encryption and decryption technologies.
• Potential Anticipated Claim(s): This patent would likely be considered for general knowledge in the field of digital content protection and encryption.

U.S. Patent Publication No. 20020013772

• Full Citation: U.S. Patent Publication No. 20020013772
• Publication/Filing Date: Not explicitly stated in the provided text, but cited as prior art to US7203844. Given the publication number format, this would be a pre-grant publication from 2002.
• Brief Description: The specific details of this publication are not provided in the excerpt. It relates to existing digital data encryption and decryption technologies.
• Potential Anticipated Claim(s): This publication likely informs the general state of the art in secure protocols or digital content protection at the time of US7203844's filing.

U.S. Pat. No. 6,226,742

• Full Citation: U.S. Pat. No. 6,226,742
• Publication/Filing Date: Not explicitly stated in the provided text, but cited as prior art to US7203844.
• Brief Description: The provided text does not offer a specific description of this patent's content, other than classifying it within the realm of digital data encryption and decryption.
• Potential Anticipated Claim(s): This patent would contribute to the understanding of the general background and existing techniques in digital security.

U.S. Pat. No. 6,101,605

• Full Citation: U.S. Pat. No. 6,101,605
• Publication/Filing Date: Not explicitly stated in the provided text, but cited as prior art to US7203844.
• Brief Description: The specific details of this patent are not included in the provided text; it's grouped with other prior art patents in encryption.
• Potential Anticipated Claim(s): This patent likely covers fundamental encryption or digital rights management techniques relevant to the broader field.

"Architectural Support for Copy and Tamper-Resistant Software" by David Lie, et al.

• Full Citation: "Architectural Support for Copy and Tamper-Resistant Software, by David Lie, et al. (Proceedings of the 9th Annual Conference on Architectural Support for Programming Languages and Operating Systems aka ASPLOS-IX, Cambridge, Mass. 2000)"
• Publication/Filing Date: 2000 (Conference Proceedings).
• Brief Description: This is a non-patent citation, an academic paper discussing architectural support for copy and tamper-resistant software. This suggests a focus on hardware and software interactions for security, potentially involving secure execution environments or tamper detection. The patent mentions that embodiments of its security protocol are designed to protect code from disassembly and modification, which aligns with the subject of this paper.
• Potential Anticipated Claim(s): This paper could potentially anticipate aspects related to secure execution of code, tamper resistance, and the interaction of hardware blocks (like the I-Cache 130 or CPU execution unit 120) with secured code, as described in US7203844's detailed description. For instance, the discussion around the CPU execution unit 120 keeping track of registers 140 when executing secure code, or implementing secure hashing functions, might be informed by such academic work. It would be highly relevant to the "system" claims (Claims 7 and 20) in terms of architectural components for security.

It is important to note that the provided text emphasizes that the security protocol described in US7203844 focuses on recursive encryption and controlling the expression of copyrighted work, and distinguishes itself from prior art by encapsulating other security protocols and not making artificial distinctions between bitstream types. Therefore, while the cited prior art may disclose elements of encryption, the novelty of US7203844 likely lies in its recursive application and the specific methods of combining and re-encrypting decryption algorithms and bitstreams, as detailed in its independent claims.

Obviousness Analysis under 35 U.S.C. § 103 for US7203844

This analysis evaluates whether the claims of US patent 7203844, "Method and system for a recursive security protocol for digital copyright control," would have been obvious to a person having ordinary skill in the art (PHOSITA) at the time of the invention, given the prior art identified in the "Prior art" section. The core inventive concept of US7203844's independent claims (Claims 1, 7, 14, and 20) revolves around a multi-layered or "recursive" encryption where not only the digital content (bit stream) is encrypted, but the decryption algorithm itself (or the combination of encrypted content and its algorithm) is subsequently encrypted with another layer, forming a nested security protocol.

Identified Prior Art References for Obviousness

1. U.S. Patent No. 6,327,652 (and other similar general encryption patents like U.S. Pat. Nos. 6,330,670, 6,412,070, 20020013772, 6,226,742, 6,101,605): These references generally disclose "basic operational categories of digital data encryption and decryption technologies" and "security protocols" for digital copyright control. They establish the foundational knowledge of encrypting digital content and associating it with a decryption method for access control.
2. "Architectural Support for Copy and Tamper-Resistant Software" by David Lie, et al. (ASPLOS-IX, 2000): This academic paper discusses architectural support for protecting software from unauthorized copying and tampering. It highlights the recognized problem in the art of securing software and digital content against sophisticated attacks and the need for robust, tamper-resistant mechanisms.
3. General knowledge in the art of cryptography and software engineering: This includes established principles such as:
   • The use of multiple, nested layers of encryption to enhance the security of sensitive data.
   • The fundamental understanding that software code, algorithms, and instructions are themselves digital data or "bit streams" that can be stored, transmitted, and thus subjected to cryptographic operations like any other digital content. Indeed, the patent itself defines a "bitstream" as "a stream of 1's and 0's" and states that "On a fundamental level, all binary digital data can be reduced to a stream of 1's and 0's (a bitstream), which can be stored and retrieved in a manner which is completely independent of the intended purpose or interpretation of that bitstream."

Obviousness Argument for US7203844 Claims

The independent claims of US7203844, exemplified by Claim 1 (method) and Claim 7 (system), describe a process where a first bit stream is encrypted and associated with a first decryption algorithm. This combination (the first encrypted bit stream and its decryption algorithm) is then itself encrypted, yielding a second encrypted bit stream associated with a second decryption algorithm. This second package is provided to a user for a two-step decryption process. Claims 14 and 20 describe a similar process utilizing a "data structure" to encapsulate the encrypted content and its decryption algorithm.

A PHOSITA in the field of digital rights management and security protocols, at the time of the invention (priority date June 20, 2002), would have been motivated to combine the known principles of encryption with the recognized need for enhanced security and tamper resistance, leading to the recursive protocol of US7203844.

Motivation for Combination:

1. Starting Point (General Encryption): A PHOSITA would begin with the established understanding of encrypting digital content and associating it with a decryption algorithm for controlled access, as broadly taught by patents like US 6,327,652. These systems provide basic copyright control.
2. Problem Recognition (Need for Enhanced Security): However, a PHOSITA would also be keenly aware of the limitations of single-layer encryption and the persistent challenge of protecting software and digital content from sophisticated attacks, including unauthorized copying and tampering. This problem is explicitly addressed in prior art such as the Lie et al. paper, which focuses on "Architectural Support for Copy and Tamper-Resistant Software." The patent itself states that "This invention relates to protecting digital content with a recursive security protocol which provides both greater security and greater flexibility than currently utilized methods." This clearly articulates the problem of improving existing security methods.
3. Applying Known Solutions (Layered Encryption and Data as Algorithms): To address the need for greater security and tamper resistance, a PHOSITA would naturally consider known methods for strengthening cryptographic protection. One fundamental and well-understood technique is to apply multiple, nested layers of encryption to particularly sensitive information. Furthermore, it is a basic tenet of digital systems that any algorithm or instruction set, whether for decryption or other purposes, is fundamentally represented as digital data—a "bit stream." The patent explicitly acknowledges this, stating, "On a fundamental level, all binary digital data can be reduced to a stream of 1's and 0's (a bitstream), which can be stored and retrieved in a manner which is completely independent of the intended purpose or interpretation of that bitstream."

Combining these elements, a PHOSITA would be motivated to:

• Take an initial digital content (first bit stream) and encrypt it, associating it with a first decryption algorithm, as commonly practiced in the art (e.g., from US 6,327,652).
• Recognizing that the decryption algorithm itself is a critical piece of digital information vulnerable to attack, and driven by the desire for enhanced tamper resistance and overall security (as emphasized by Lie et al.), the PHOSITA would logically seek to protect this decryption algorithm more robustly.
• Applying the known principle of layered encryption to this entire security package, it would be obvious to combine the first encrypted bit stream and its first decryption algorithm (potentially within a routine "data structure" for organized handling, as in Claim 14) and then subject this entire combination to a second layer of encryption. This action treats the entire initial security wrapper as a new "bit stream" to be further protected.
• The resulting "second bit stream" would then be associated with a "second decryption algorithm," the use of which would initiate the two-step recursive decryption process. The decryption steps are merely the logical inverse of the encryption process and would be obvious once the recursive encryption scheme is established.

This combination would yield a more resilient and flexible security protocol, addressing the recognized need for stronger digital copyright control and tamper-resistant software. The "recursive" nature of the protocol directly flows from the obvious application of layered security to all digital components requiring protection, including the protection mechanisms themselves. Therefore, the claimed invention, which essentially applies a well-known security enhancement (multi-layered encryption) to both content and its associated decryption instructions (understood as digital data), would have been obvious.