Inter Partes Review of
`U.S. Patent No. 9,948,625
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`_____________________
`
`Zoom Video Communications, Inc.,
`Petitioner,
`
`v.
`
`Cyph, Inc.,
`Patent Owner.
`______________________________________________________________
`
`Case No. IPR2023-00140
`
`U.S. Patent No. 9,948,625
`Issue Date: April 17, 2018
`
`
`
`
`
`PETITION FOR INTER PARTES REVIEW OF
`U.S. PATENT NO. 9,948,625
`
`
`
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`
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`
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`
`

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`Inter Partes Review of
`U.S. Patent No. 9,948,625
`TABLE OF CONTENTS
`
`Page
`
`V.
`
`C.
`
`I.
`INTRODUCTION ........................................................................................ 1
`GROUNDS FOR STANDING (37 C.F.R. § 42.104(A)) ............................... 2
`II.
`IDENTIFICATION OF CHALLENGES (37 C.F.R. § 42.104(B))................ 2
`III.
`IV. TECHNOLOGY BACKGROUND............................................................... 3
`A.
`Cryptography and Encryption ............................................................. 3
`B.
`Key Distribution in Symmetric Encryption ......................................... 5
`THE ’625 PATENT ...................................................................................... 6
`A.
`Specification ....................................................................................... 6
`B.
`Prosecution History............................................................................. 7
`VI. PERSON OF ORDINARY SKILL IN THE ART ....................................... 10
`VII. CLAIM CONSTRUCTION ........................................................................ 11
`VIII. OVERVIEW OF THE PRIOR ART ........................................................... 13
`A. U.S. Patent No. 6,363,154 (“Peyravian”; Ex. 1005) .......................... 13
`B.
`UK Patent Application Publication No. GB 2 422 277 (“Yeun”; Ex.
`1006) ................................................................................................ 15
`National Institute of Standards & Technology, Special Publication
`800-90A (“Barker”; Ex. 1023) .......................................................... 17
`IX. GROUNDS ................................................................................................. 18
`A. Ground 1: Claims 1 and 2 Are Obvious Over Peyravian ................... 18
`1.
`Claim 1 ................................................................................... 18
`a.
`[1.0] “A method, comprising:” ...................................... 18
`b.
`[1.1] “generating a shared symmetric key to begin a
`communication session among a group of users by a first
`user;” ............................................................................ 18
`[1.2] “distributing, by the first user, the generated shared
`symmetric key to each user in the group of users;” ....... 23
`
`c.
`
`
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`
`i
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`

`

`d.
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`e.
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`f.
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`g.
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`b.
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`c.
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`d.
`
`e.
`
`f.
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`[1.3] “communicating within the communication session
`among a group of users, wherein” ................................. 24
`[1.4] “each user encrypts a message to the group of users
`to be distributed through the communication session
`using the generated shared symmetric key, and” ........... 26
`[1.5] “each user decrypts a message received from the
`communication session using the generated shared
`symmetric key;” ............................................................ 28
`[1.6] “wherein additional users are added to the existing
`communication session when the first user distributes to
`the additional users the generated shared symmetric key.”
`...................................................................................... 29
`Claim 2 ................................................................................... 30
`a.
`[2.0] “The method of claim 1, further comprising
`changing users within the group of users to reform the
`communication session among a new group of users
`comprises:” ................................................................... 30
`[2.1] “generating a new shared symmetric key by the first
`user;” ............................................................................ 31
`[2.2] “distributing, by the first user, the generated new
`shared symmetric key to each user in the new group of
`users;” ........................................................................... 32
`[2.3] “communicating to the communication session
`among a new group of users, wherein” ......................... 32
`[2.4] “each user encrypts a message to the new group of
`users to be distributed through the communication
`session using the generated new shared symmetric key,
`and” .............................................................................. 33
`[2.5] “each user decrypts a message received from the
`communication session using the generated new shared
`symmetric key.” ............................................................ 34
`Ground 2: Claims 1 and 2 Are Obvious Over Yeun in View of Barker
`.......................................................................................................... 36
`1.
`Obviousness to a POSA .......................................................... 36
`a. Motivation to Combine ................................................. 36
`b.
`Reasonable Expectation of Success ............................... 37
`Claim 1 ................................................................................... 38
`a.
`[1.0] “A method, comprising:” ...................................... 38
`
`2.
`
`2.
`
`B.
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`
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`ii
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`b.
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`c.
`
`d.
`
`e.
`
`f.
`
`g.
`
`[1.1] “generating a shared symmetric key to begin a
`communication session among a group of users by a first
`user;” ............................................................................ 39
`[1.2] “distributing, by the first user, the generated shared
`symmetric key to each user in the group of users;” ....... 43
`[1.3] “communicating within the communication session
`among a group of users, wherein” ................................. 44
`[1.4] “each user encrypts a message to the group of users
`to be distributed through the communication session
`using the generated shared symmetric key, and” ........... 45
`[1.5] “each user decrypts a message received from the
`communication session using the generated shared
`symmetric key;” ............................................................ 49
`[1.6] “wherein additional users are added to the existing
`communication session when the first user distributes to
`the additional users the generated shared symmetric key.”
`...................................................................................... 50
`Claim 2 ................................................................................... 51
`a.
`[2.0] “The method of claim 1, further comprising
`changing users within the group of users to reform the
`communication session among a new group of users
`comprises:” ................................................................... 51
`[2.1] “generating a new shared symmetric key by the first
`user;” ............................................................................ 52
`[2.2] “distributing, by the first user, the generated new
`shared symmetric key to each user in the new group of
`users;” ........................................................................... 54
`[2.3] “communicating to the communication session
`among a new group of users, wherein” ......................... 54
`[2.4] “each user encrypts a message to the new group of
`users to be distributed through the communication
`session using the generated new shared symmetric key,
`and” .............................................................................. 55
`[2.5] “each user decrypts a message received from the
`communication session using the generated new shared
`symmetric key.” ............................................................ 57
`X. NO SECONDARY CONSIDERATIONS................................................... 58
`XI. DISCRETIONARY DENIAL IS NOT APPROPRIATE ............................ 59
`
`3.
`
`b.
`
`c.
`
`d.
`
`e.
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`f.
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`iii
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`2.
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`3.
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`4.
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`5.
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`6.
`
`A.
`
`B.
`
`Advanced Bionics and Becton, Dickinson Factors Do Not Support
`Discretionary Denial ......................................................................... 59
`Fintiv Factors Do Not Favor Discretionary Denial ............................ 60
`1.
`First Factor: whether a stay exists or is likely to be granted if a
`proceeding is instituted ........................................................... 60
`Second Factor: proximity of the court’s trial date to the Board’s
`projected statutory deadline for a final written decision .......... 61
`Third Factor: investment in the parallel proceeding by the court
`and the parties ......................................................................... 62
`Fourth Factor: overlap between issues raised in the petition and
`in the parallel proceeding ........................................................ 62
`Fifth Factor: whether the petitioner and the defendant in the
`parallel proceeding are the same party .................................... 63
`Sixth Factor: other circumstances that impact the Board’s
`exercise of discretion, including the merits ............................. 63
`General Plastic Does Not Apply....................................................... 63
`C.
`XII. MANDATORY NOTICES (37 C.F.R. § 42.8)............................................ 63
`A.
`Real Party-In-Interest ........................................................................ 63
`B.
`Related Matters ................................................................................. 63
`C.
`Lead and Back-Up Counsel and Service Information ........................ 64
`XIII. PAYMENT OF FEES (37 C.F.R. §§ 42.15(A) & 42.103) .......................... 65
`XIV. CONCLUSION .......................................................................................... 65
`
`
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`iv
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`

`TABLE OF AUTHORITIES
`
` Page(s)
`
`Cases
`Advanced Bionics, LLC v. Med-El Elektromedizinische Geräte GmbH,
`IPR2019-01469 (P.T.A.B. Feb. 13, 2020) ........................................................ 59
`Becton, Dickinson, & Co. v. B. Braun Melsungen AG,
`IPR2017-01586 (P.T.A.B. Dec. 15, 2017)........................................................ 59
`
`Brown v. 3M,
`265 F.3d 1349 (Fed. Cir. 2001) ........................................................................ 12
`Gen. Plastic Indus. Co., Ltd. v. Canon Kubushiki Kaisha,
`IPR2016-01357 (P.T.A.B. Sept. 6, 2017) ......................................................... 63
`Phillips v. AWH Corp.,
`415 F.3d 1303 (Fed. Cir. 2005) ........................................................................ 11
`Samsung Elecs. Co., Ltd v. Staton Techiya, LLC,
`IPR2022-00302 (P.T.A.B. July 11, 2022) .................................................. 61, 62
`Sand Revolution II, LLC v. Continental Intermodal Group-Trucking LLC,
`IPR2019-01393 (P.T.A.B. June 16, 2020) ........................................................ 61
`Statutes
`35 U.S.C. § 102(a) .................................................................................... 13, 15, 17
`35 U.S.C. § 103 ........................................................................................ 3, 8, 9, 10
`Other Authorities
`37 C.F.R. § 42.10(b) ............................................................................................. 64
`Interim Procedure for Discretionary Denials in AIA Post-Grant
`Proceedings with Parallel District Court Litigation
`(USPTO June 21, 2022) ............................................................................. 60, 62
`
`
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`v
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`

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`TABLE OF EXHIBITS
`
`Exhibit No. Description
`1001
`U.S. Patent No. 9,948,625 (“’625 patent”)
`
`1002
`
`1003
`
`1004
`
`1005
`
`1006
`
`1007
`
`1008
`
`1009
`
`File History for the ’625 patent (“’625 patent FH”)
`
`Declaration of Dr. Thomas Ristenpart (“Ristenpart Decl.”)
`
`Curriculum Vitae of Dr. Thomas Ristenpart
`
`U.S. Patent No. 6,363,154 (“Peyravian”)
`
`UK Patent Application Publication No. GB 2 422 277 (“Yeun”)
`
`Gustavus J. Simmons, Symmetric and Asymmetric Encryption,
`Vol. 11, No. 4 ACM Computing Surveys 305-330 (Dec. 1979),
`available at https://dl.acm.org/doi/10.1145/356789.356793
`
`Whitfield Diffie & Martin E. Hellman, New Directions in
`Cryptography, IEEE Trans. on Information Theory, vol. IT-22, no.
`6, pp. 644-654 (Nov. 1976), available at
`https://ieeexplore.ieee.org/document/1055638;
`https://ee.stanford.edu/~hellman/publications/24.pdf
`
`R.L. Rivest, A. Shamir, and L. Adleman, A Method for Obtaining
`Digital Signatures and Public-Key Cryptosystems, Commc’n of
`the ACM, vol. 21, no. 2, pp. 120-126 (Feb. 1978), available at
`https://dl.acm.org/doi/10.1145/359340.359342
`
`1010
`
`U.S. Patent No. 4,405,829
`
`1011
`
`Neal Koblitz, Elliptic Curve Cryptosystems, Mathematics of
`Computation, vol. 48, no. 177, pp. 203-209 (Jan. 1987), available
`at https://www.jstor.org/stable/2007884;
`https://www.ams.org/journals/mcom/1987-48-177/S0025-5718-
`1987-0866109-5/
`
`
`
`
`
`vi
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`

`

`Exhibit No. Description
`Nat’l Inst. of Standards & Tech., U.S. Dep’t. of Com., FIPS PUB
`180-1 (Secure Hash Standard) (Apr. 17, 1995) (withdrawn on
`Aug. 1, 2002, and superseded by FIPS 180-2), available at
`https://csrc.nist.gov/publications/detail/fips/180/1/archive/1995-
`04-17
`
`1012
`
`1013
`
`1014
`
`1015
`
`1016
`
`1017
`
`1018
`
`Nat’l Inst. of Standards & Tech., U.S. Dep’t. of Com., FIPS PUB
`180-4 (Secure Hash Standard (SHS)) (Mar. 2012) (withdrawn on
`Aug. 5, 2015), available at
`https://csrc.nist.gov/publications/detail/fips/180/4/archive/2012-
`03-06
`
`Simon Singh, THE CODE BOOK: THE SCIENCE OF SECRECY FROM
`ANCIENT EGYPT TO QUANTUM CRYPTOGRAPHY (First Anchor
`Books Ed., Sept. 2000), available at https://books-
`library.net/files/books-library.net-04040109Rq2I5.pdf (“The Code
`Book”)
`
`Cyph, Inc. v. Zoom Video Communications, Inc., No. 4:22-cv-
`00561-JSW, Dkt. No. 58 (N.D. Cal. July 11, 2022)
`
`Raymond B. Jennings III et al., A Study of Internet Instant
`Messaging and Chat Protocols, Vol. 20, Issue 4 IEEE Network
`pp. 16-21 (July/August 2006), available at
`https://ieeexplore.ieee.org/document/1668399
`
`Bazara I.A. Barry & Fatma M. Tom, Instant Messaging:
`Standards, Protocols, Applications, and Research Directions, in
`INTERNET POLICIES AND ISSUES, VOL. 7 1-15 (Chapter 8) (B.G.
`Kutais ed., Nova Science Publishers, Inc. 2010), available at
`https://www.researchgate.net/publication/280307922_Instant_Mes
`saging_Standards_Protocols_Applications_and_Research_Directio
`ns
`
`Adam Pash, Chat with AIM, MSN, Yahoo, and other contacts over
`Google Talk, LifeHacker (Aug. 14, 2007),
`https://lifehacker.com/chat-with-aim-msn-yahoo-and-other-
`contacts-over-goog-289097
`
`
`
`
`
`vii
`
`
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`

`

`Exhibit No. Description
`Cyph, Inc. v. Zoom Video Communications, Inc., No. 22-cv-
`00561-JSW, Dkt. No. 74 (N.D. Cal. Oct. 7, 2022), Dkt. No. 75
`(N.D. Cal. Oct. 11, 2022).
`
`1019
`
`Table N/A—U.S. District Courts-Combined Civil and Criminal
`Federal Court Management Statistics (June 30, 2022),
`https://www.uscourts.gov/statistics/table/na/federal-court-
`management-statistics/2022/06/30-2
`
`Cyph, Inc. v. Zoom Video Communications, Inc., No. 21-cv-
`03027-RM-MEH, Dkt. No. 32 (D. Co. Jan. 27, 2022)
`
`National Institute of Standards and Technology’s Cryptography
`website, https://www.nist.gov/cryptography
`
`Nat’l Inst. of Standards & Tech., U.S. Dep’t. of Com., NIST SP
`800-90A (Recommendation for Random Number Generation
`Using Deterministic Random Bit Generators) (January 23, 2012)
`(withdrawn June 2015, and superseded by SP 800-90A Revision
`1), available at
`https://www.nist.gov/publications/recommendation-random-
`number-generation-using-deterministic-random-bit-generators-
`3?pub_id=910345
`
`Nat’l Inst. of Standards & Tech., U.S. Dep’t. of Com., FIPS PUB
`197 (Advanced Encryption Standard (AES)) (Nov. 26, 2001),
`available at https://www.nist.gov/publications/advanced-
`encryption-standard-aes
`
`Nat’l Inst. of Standards & Tech., U.S. Dep’t. of Com., FIPS PUB
`46 (Data Encryption Standard (DES)) (Jan. 15, 1977), available at
`https://csrc.nist.gov/publications/detail/fips/46/archive/1977-01-15
`
`1020
`
`1021
`
`1022
`
`1023
`
`1024
`
`1025
`
`
`
`
`
`
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`viii
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`
`
`I.
`
`INTRODUCTION
`U.S. Patent No. 9,948,625 (the “’625 patent”) relates to encrypted group
`
`communication methods, and in particular, a communication session among a
`
`group of users who encrypt and decrypt data using the same key. As shown below,
`
`the claimed methods are nothing new and amount to nothing more than the routine
`
`use of basic encryption concepts known long before the 2015 earliest possible
`
`priority date for the ’625 patent.
`
`Encryption is the process of turning plain, original messages into
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`unintelligible, scrambled data; decryption is the process of turning the scrambled
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`data back to the original messages. An encryption key specifies the exact details of
`
`particular encryption and decryption methods. When, as is claimed in the ’625
`
`patent, users encrypt and decrypt data using the same key, that is referred to as
`
`“symmetric” or “symmetric key” encryption—a technique that long predates the
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`’625 patent. Because whoever knows the key used for encrypting a message can
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`also decrypt that message in symmetric encryption, it has also long been known
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`that it is vital to distribute the key only to the authorized parties to the
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`communication and to safeguard the key among them.
`
`The ’625 patent adds nothing new to these old concepts. The purported
`
`invention reflected in claims 1 and 2 of the ’625 patent (“challenged claims”) is to
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`use the same key that was previously used to form the communication session
`
`1
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`

`

`
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`when adding new users to the “existing communication session.” Ex. 1001, 10:32-
`
`35; Ex. 1002, 28-32, 98-102. But the idea of using the same key to add new users
`
`to the existing communication session was also not new, and was taught by the
`
`prior art. The Examiner, however, was not given the opportunity to consider the
`
`references discussed in this Petition, nor any analogous prior art. Indeed, not even
`
`a single Information Disclosure Statement (“IDS”) was filed by Applicant during
`
`prosecution—all of the references considered during prosecution were located by
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`the Examiner, without help from Applicant. Those unassisted searches did not
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`locate the art discussed below, which art demonstrates that the challenged claims
`
`are unpatentable obvious combinations of well-known elements. Because this
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`Petition demonstrates a reasonable likelihood that at least one of the challenged
`
`claims is obvious, Petitioner respectfully requests that trial be instituted.
`
`II. GROUNDS FOR STANDING (37 C.F.R. § 42.104(a))
`Petitioner certifies that the patent for which review is sought is available for
`
`inter partes review and that the Petitioner is not barred or estopped from requesting
`
`an inter partes review challenging the patent claims on the grounds identified in
`
`this Petition.
`
`III.
`
`IDENTIFICATION OF CHALLENGES (37 C.F.R. § 42.104(b))
`Petitioner requests that the Board institute inter partes review of the
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`challenged claims on the following grounds:
`
`2
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`

`

`
`
`Ground 1: Claims 1 and 2 are unpatentable under 35 U.S.C. § 103 as
`
`obvious over Peyravian (Ex. 1005).
`
`Ground 2: Claims 1 and 2 are unpatentable under 35 U.S.C. § 103 as
`
`obvious over Yeun (Ex. 1006) in view of Barker (Ex. 1023).
`
`IV. TECHNOLOGY BACKGROUND
`A. Cryptography and Encryption
`Cryptography seeks to prevent an unauthorized and unintended receiver
`
`from determining the content of the message being communicated. Ex. 1007, 2.
`
`Encryption is an application of cryptography. It produces an unintelligible,
`
`scrambled message by applying a key to a plain, original message. Ex. 1014, 26;
`
`Ex. 1007, 3. One of the benefits of cryptography is that only the key needs to be
`
`kept secret from unauthorized parties. See Ex. 1014, 26; Ex. 1007, 3; Ex. 1003, ¶
`
`32. Thus, only the authorized receiver, who has the right key, should be able to
`
`recover (i.e., decrypt) the message; an unauthorized receiver should not be able to
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`deduce either the message or the unknown key. Id.
`
`The use of keys for purposes of encryption is ancient. Julius Caesar
`
`famously used a substitution shift (the “Caesar shift”) that replaces each letter in
`
`the message with the letter three places further on in the alphabet (i.e., key) to send
`
`a message to Cicero. Ex. 1014, 24-27 (for example, “veni, vidi, vici” is encrypted
`
`to “YHQL, YLGL, YLFL”); see Ex. 1007, 3. The “key” to this encryption is that
`
`3
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`

`

`
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`each letter was replaced by the letter three places further on. The reader who
`
`knows this key can recover the original message by reversing the encryption
`
`process and replacing each letter by the letter three places ahead in the alphabet.
`
`The Caesar shift is an example of “symmetric” or “symmetric key”
`
`encryption. The same key, or keys that can be easily computed from each other, is
`
`used for both encryption and decryption. Ex. 1007, 1, 12-14; see Ex. 1008, 1-3;
`
`see also Ex. 1003, ¶ 37.
`
`For decades, one of the leaders in modern cryptography and in public
`
`collaborations for developing modern cryptography has been the National Institute
`
`of Standards and Technology (“NIST”). See Ex. 1022; Ex. 1003, ¶ 40. NIST has
`
`been a recognized leader in cryptography since at least 1977 when it published the
`
`Data Encryption Standard, and NIST continues to publish encryptions standards
`
`and recommendations to this day. See Ex. 1022; see also, e.g., Exs. 1012-1013,
`
`1023-1025; Ex. 1003, ¶ 40. Cryptographic solutions from NIST are regularly used
`
`today by the US Government and in commercial applications, such as tablets,
`
`cellphones, and ATMs. Ex. 1022; Ex. 1003, ¶ 41. For decades, NIST technical
`
`publications have been a publicly available source of detailed information on
`
`numerous aspects of cryptography, and well known to persons working in the field
`
`of cryptography. Id., ¶ 41.
`
`4
`
`

`

`
`
`B. Key Distribution in Symmetric Encryption
`Because anyone who knows the symmetric key can decrypt the message
`
`encrypted with it, the symmetric key must remain a secret known only to the
`
`authorized parties to the communication. Ex. 1003, ¶ 42; see Ex. 1008, 1-2. For
`
`this reason, symmetric encryption is also known as “secret key” cryptography. Ex.
`
`1003, ¶ 37. In other words, only the authorized parties to the communication can
`
`possess the symmetric key. Ex. 1008, 1-3; see also Ex. 1003, ¶¶ 37, 42. Thus,
`
`secure distribution of the symmetric key has also long been known to be critical.
`
`Ex. 1008, 1-3; see also Ex. 1003, ¶¶ 37, 42.
`
`When the key to be distributed is electronic as opposed to, e.g., a codebook,
`
`distribution can be securely accomplished using various key distribution protocols
`
`that were developed as early as the mid-1970s and that became publicly available
`
`and were widely used in electronic communications such as web browsers, emails,
`
`and chat applications decades before 2015. Ex. 1003, ¶¶ 43-45; see also generally
`
`Exs. 1007-1011. For example, a symmetric key can be encrypted with a second
`
`key before being distributed, and in a way that the encrypted symmetric key can be
`
`recovered by a third key, which is known only to the receiver.1 E.g., Ex. 1005,
`
`6:43-47; see also Ex. 1003, ¶¶ 44-45.
`
`
`1 This method is known as “public key” cryptography and uses a pair of separate
`
`
`
`5
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`

`

`
`
`V. THE ’625 PATENT
`Specification
`A.
`The ’625 patent issued on April 17, 2018, from a U.S. application filed on
`
`August 31, 2015, which claims priority to a U.S. provisional application filed on
`
`January 7, 2015.2
`
`The ’625 patent is entitled “Encrypted Group Communication Method” and
`
`states that it “provide[s] a method of encrypted group communication.” Ex. 1001,
`
`3:21-22. The ’625 patent acknowledges that the encrypted group communication
`
`systems were well known in the art. Id., 2:4-25, 3:26-33. According to the ’625
`
`patent, however, such conventional systems “require significant resources to
`
`encrypt and maintain encrypted group communications.” Id., 3:26-29. The patent
`
`
`keys—one to encrypt and another to decrypt a message. Ex. 1007, 14-15; Ex.
`
`1008, 1, 4–5; see also Ex. 1003, ¶ 39. The key used to encrypt the message is
`
`available to others (so that anyone can encrypt with it), while the key used to
`
`decrypt the message remains secret and private to an authorized party (so that only
`
`the authorized party can decrypt). Ex. 1008, 1, 5; see also Ex. 1003, ¶ 39.
`
`2 For the purposes of this proceeding, Petitioner assumes January 7, 2015 as the
`
`’625 patent’s effective filing date. Petitioner reserves the right to contest this or
`
`any earlier priority date in this and in any related proceedings.
`
`6
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`

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`
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`purports to provide systems that are “more efficient in computation use and
`
`network bandwidth use,” and that are “simple, and more convenient, to implement,
`
`compared to conventional” systems. Id., 3:26-44.
`
`According to the ’625 patent, when a first user (Alice) intends to engage a
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`group of other users (Bob, Carl, and David) for communication, Alice specifies all
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`users in the group, initiates a group communication session, and generates a shared
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`symmetric key to be used by the group. Id., 3:21-26, 3:51-58. Alice then
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`“distributes the shared symmetric key individually to” Bob, Carl, and David. Id.,
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`3:58-4:4. All users to the group (Alice, Bob, Carl, and David) can communicate
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`with each other securely by encrypting and decrypting their communications using
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`the shared symmetric key that is now in each user’s possession. Id., 4:5-9.
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`Additional users can be added “when the first user distributes to the additional
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`users the generated shared symmetric key.” Id. 2:40-43. Additionally, when a new
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`user joins the group or an existing user leaves the group, the most senior member
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`(Alice in this example) may generate and redistribute a new shared symmetric key
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`to be used by the new group. Id., 4:2-4.
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`Prosecution History
`B.
`As filed, the application that issued as the ’625 patent included one
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`independent and two dependent claims. Ex. 1002, 190-191.
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`The Examiner rejected all claims under 35 U.S.C. § 103 over Nordholt (U.S.
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`Publication No. 2013/0101121) in view of Slater (U.S. Publication No.
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`2011/0307695). Id., 143-147. Independent claim 1 did not, at this time, include
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`any step in which additional users were added. Dependent claim 2 included a step
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`that “wherein additional users are added to the communication session when the
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`first user distributes to the additional users the generated shared symmetric key.”
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`Id., 190-191. In rejecting claim 2, the Examiner relied on a disclosure in the prior
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`art that “as new users are added to the group, [a] new shared key is generated.” Id.,
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`145.
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`In response, Applicant amended independent claim 1 to incorporate the
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`requirements of claim 2 and cancelled claim 2. Applicant argued that the teaching
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`of “as new users are added to the group, new shared key is generated” is
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`“clearly different” from the claimed step of “generating a shared symmetric key
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`to begin a communication session among a group of users by a first user” and
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`specifically from “wherein additional users are added to the communication
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`session when the first user distributes to the additional users the generated
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`shared symmetric key.” Id., 135-136 (emphasis in original). Applicant argued
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`that because claim 3 depended from the amended claim 1, it, too, was allowable.
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`Id., 132-133.
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`In the following office action, the Examiner again rejected all pending
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`claims under 35 U.S.C. § 103 over Nordholt in view of Slater. Id., 112-117. In
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`response, Applicant narrowed claim 1 such that the claim read, “additional users
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`are added to the existing communication session when the first user distributes to
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`the additional users the generated shared symmetric key.” Id., 98; see also id., 67,
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`79. Applicant argued that the prior art teachings were “clearly different” from the
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`amended claim “since [the claim] does not involve generating a new key as
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`additional users are added to the existing communication session.” Id., 101
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`(emphasis in original); see also id., 70, 83.
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`The Examiner again rejected all pending claims under 35 U.S.C. § 103 over
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`Nordholt in view of Slater and in further view of Gehrmann (U.S. Publication No.
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`2015/0195261).3 Id., 49-53. Applicant did not further amend the claims in
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`response, but instead argued that “Re-keying” taught by Gehrmann “must involve
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`3 Pending claims were also rejected on the ground of nonstatutory double patenting
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`over then pending U.S. Patent Application No. 14/841,339, which issued as U.S.
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`Patent No. 10,003,465. See Ex. 1002, 46–48. Applicant filed a terminal
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`disclaimer. Id., 30, 41. Petitioner seeks an inter partes review of claims 1, 4, 5, 8,
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`11, 12, and 15 of the ’465 patent in IPR2023-00141, which has or will soon be
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`submitted to the Board.
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`generating a new unique key for the added group member” and therefore does not
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`teach the “wherein additional users are added to the existing communication
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`session when the first user distributes to the additional users the generated shared
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`symmetric key” requirement of claim 1. Id., 28-32 (emphasis in original). The
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`Examiner withdrew the § 103 rejections, and claims 1 and 3 were allowed in the
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`current form as claims 1 and 2, respectively. Id., 11-14.
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`VI. PERSON OF ORDINARY SKILL IN THE ART
`The subject matter of the ’625 patent relates to a group communication
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`system and method based on symmetric encryption. A person of ordinary skill in
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`the art (“POSA”) in this subject matter as of January 2015 would have at least a
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`bachelor’s degree (or equivalent) in applied mathematics, computer science,
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`computer engineering, electrical engineering, or a related field, and at least one
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`year of undergraduate (or higher level) coursework, industry experience, or
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`equivalent research experience in the field of cryptography, and at least one year of
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`undergraduate (or higher) coursework, industry experience, or equivalent research
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`experience in the field of instant messaging or chat applications, video- or audio-
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`conferencing applications. Ex. 1003, ¶ 11. This description is approximate, and a
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`higher level of education or skill might make up for less experience, and vice
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`versa. Id. This Petition does not rely on this precise definition, and the challenged
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`10
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`claims would be unpatentable from the perspective of any reasonable level of
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`ordinary skill.
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`VII. CLAIM CONSTRUCTION
`The prior art relied upon in this Petition discloses the subject matter of the
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`challenged claims under any reasonable claim interpretation, including their plain
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`and ordinary meanings. See Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir.
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`2005). Petitioner does not believe any claim terms require a specific construction.
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`Throughout this Petition, the plain and ordinary meaning of the claim terms is
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`applied.4 See id. at 1312-13.
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`In the pending district court case Patent Owner has argued that the limitation
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`“wherein additional users are added to the existing communication session when
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`the first user distributes to the additional users the generated shared symmetric
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`key” (element [1.6]) “is a conditional statement that is not performed in all
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`instances” and requires that “the referenced step [be] performed only when
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`‘additional users’ are desired to be added.” Ex. 1015, 10-11 (emphasis in original).
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`Patent Owner thus appears to contend that the limitation is optional, and that
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`infringement can occur whether or not additional users are added. Because patent
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`4 Petitioner reserves the right to argue alternative constructions in other
`proceedings including, where such a defense is available, that the claims are
`indefinite.
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`11
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`claims must be read the same for purposes of infringement and invalidity, see
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`Brown v. 3M, 265 F.3d 1349, 1352 (Fed. Cir. 2001), Petitioner addresses here the
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`contention that the limitation is optional.
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`Based on the claim language and the prosecution history, element [1.6] is
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`not optional. The claim step requires that “additional users are added to the
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`existing communication session,” and requires that such addition happen at a
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`particular time and in a particular way: “when the first user distributes to the
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`additional users the generated shared s