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` UNITED STATES PATENT AND TRADEMARK OFFICE
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`BEFORE THE PATENT TRIAL AND APPEAL BOARD
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`APPLE INC.,
`Petitioner,
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`v.
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`ERICSSON AB,
`Patent Owner.
`____________________
`
`Case IPR2022-00618
`Patent No. 9,313,178
`____________________
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`
`
`PATENT OWNER’S RESPONSE
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`Google Exhibit 1029
`Google v. Ericsson
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`TABLE OF CONTENTS
`
`
`Introduction
`Background of the ’178 Patent and the challenged claims
`Person of ordinary skill in the art
`
`The Petition fails to meet limitation 1.4 and 16.5, properly construed, and
`thus fails as to all challenged claims.
`“[D]etecting content encryption key rotation boundaries between
`periods of use” should be construed to mean detecting key rotation
`boundaries before normal period-based expiration
`Patent Owner’s claim construction is not inconsistent with the
`concerns expressed in the Institution Decision
`The Petition’s theory cannot meet the challenged claims under the
`correct interpretation of limitations 1.4 and 16.5
`
`I.(cid:3)
`II.(cid:3)
`III.(cid:3)
`IV.(cid:3) The Petition fails to meet claims 6, 12-15, and 20
`V.(cid:3)
`A.(cid:3)
`B.(cid:3)
`C.(cid:3)
`VI.(cid:3) Conclusion
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`Case IPR2022-00618
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`1(cid:3)
`3(cid:3)
`6(cid:3)
`7(cid:3)
`10(cid:3)
`11(cid:3)
`17(cid:3)
`21(cid:3)
`22(cid:3)
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`EXHIBIT LIST
`
`
`Description
`Declaration of Kayvan B. Noroozi in Support of Motion for
`Admission Pro Hac Vice
`U.S. Patent Publ. No. 2014/0237243 (publication of U.S.
`Application No. 14/266,368 filed April 30, 2014)
`U.S. Provisional Application Ser. No. 61/500,316, filed Jun.
`23, 2011
`U.S. Patent No 2012/0331293(Publication of U.S. Patent
`Application Ser. No.: 13/530,997, filed on Jun. 22, 2012)
`
`
`
`Exhibit No.
`2001
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`2002
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`2003
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`2004
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`I.
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`Introduction
`As the Board’s Institution Decision recognized, the Petition does not
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`demonstrate unpatentability at least as to claims 6, 12-15, and 20.
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`Claim 6 recites prefetching a next key “after the expected expiration of the
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`content encryption key currently being applied. . . .” Ex. 1001 at 12:40-47
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`(emphasis added). The claim is thus directed to the situation where a current key is
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`not expired by the packager 104 at the expected expiration time suggested by the
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`workflow manager 102, and a new key is prefetched (i.e., obtained prior to the
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`retirement of the current key) after the expected expiration time of the current key.
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`The Petition, by contrast, attempts to meet claim 6 by alleging that in the
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`combination Peterka and Bocharov, “a client device would request a new content
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`encryption key . . . before the expected expiration of the content encryption key
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`currently being applied,” Pet. at 40 (emphasis added)—the exact opposite of what
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`claim 6 requires. The Petition thus cannot prevail as to claim 6.
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`The Petition likewise fails as to claims 12-15 and 20. Whereas those claims
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`require that the client issue a request for a new key, the Petition’s theory relies on
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`an embodiment in Peterka in which “new keys are not received in response to [a]
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`request from the client for a new key,” as the Board has correctly found. Paper 11
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`at 26; see also id. at 22 n. 6. Accordingly, the Petition cannot establish
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`
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`unpatentability as to claims 12-15 and 20.
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`Moreover, as this Response demonstrates, the Petition’s theory fails to meet
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`independent claims 1 and 16, and thus all challenged claims, under the proper
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`construction of “detecting content encryption key rotation boundaries between
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`periods of use,” as recited in limitations 1.4 and 16.5. The ’178 patent’s
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`specification consistently teaches that “period of use” and similar phrases refer to
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`the normal period-based duration set for an encryption key. See Section V.A, infra.
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`The claims’ requirement of “detecting content encryption key rotation boundaries
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`between periods of use” is thus limited to detecting rotation boundaries that arise
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`before the normal period-based expiration time for a current key, such as due to a
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`key change notification issued by the server. Accordingly, the claims cannot be
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`met by a method or a system that is incapable of detecting pre-expiration time
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`rotation boundaries.
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`At the same time, as demonstrated below, Patent Owner’s claim construction
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`is not inconsistent with the concerns raised by the Board in its Institution Decision.
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`See Section V.B, infra. As an initial matter, Patent Owner’s construction does not
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`exclude from the scope of the claims the embodiment of changing encryption keys
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`based on the expiration time of a current key. Rather, that embodiment is captured
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`by limitations 1.5 and 16.6 and is fully within the scope of the claims, provided
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`
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`that the “detecting” requirement of limitations 1.4 and 16.5 is met. Moreover,
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`Patent Owner’s construction is also consistent with the Board’s grammatical
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`analysis of limitations 1.4 and 16.5, as well as the specification’s teachings
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`regarding steps 316 and 308 of Figure 3, which the Board had emphasized.
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`By contrast, construing the claims to encompass a method or system that
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`cannot detect pre-expiration time rotation boundaries would fail to give meaning
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`to the phrase “between periods of use,” and would be inconsistent with core claim
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`construction principles. SIPCO, LLC v. Emerson Elec. Co., 939 F.3d 1301, 1307
`
`(Fed. Cir. 2019) (quoting Innova/Pure Water, Inc. v. Safari Water Filtration Sys.,
`
`Inc., 381 F.3d 1111, 1119 (Fed. Cir. 2004)).
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`Because the Petition’s only relevant theory—which relies on Peterka’s
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`“pull” embodiment—exclusively requests new keys based on the expiration time
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`of the current key, and lacks any ability to detect pre-expiration time key rotation
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`boundaries, the Petition fails to demonstrate unpatentability under the proper
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`construction of the challenged claims. See Section V.C, infra.
`
`II. Background of the ’178 Patent and the challenged claims
`United States Patent 9,313,178 (“the ’178 Patent”), titled “Method and
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`System for Secure Over-The-Top Live Video Delivery,” is directed to a method
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`“for managing key rotation (use of series of keys) and secure key distribution in
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`
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`over-the-top content delivery.” Ex. 1001 at 1, Abstract. The ’178 Patent has 20
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`claims. The only independent claims are claim 1, which is directed to a method for
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`handling secure distribution of content, and claim 16, which is directed to a
`
`computerized device operable as a client for handling secure distribution of
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`content.
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`
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`The ’178 Patent teaches that “[a]s content delivery models move away from
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`streaming distribution over private networks to Web-based delivery of files over
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`the public Internet, referred to as over-the-top (OTT) delivery, traditional content
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`protection paradigms must be modified to support new delivery protocols, e.g.,
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`HTTP Live Streaming. For live streaming content with long or indefinite durations,
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`use of a single encryption key for the entire duration increases the probability that
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`the key may be compromised.” Ex. 1001 at 1:15-26. The ’178 Patent teaches that
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`“[t]here are many protocols and methods for generating segmented content . . .
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`each segment is independently playable, and therefore needs to be independently
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`encrypted and decryptable. Segments are typically of a fixed duration and, in the
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`case of video content, begin with a key-frame and contain no inter-segment
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`references. Segmentation is performed on each of the different encoding generated
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`by the transcoder, by parsing the resultant encoding and determining segment
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`boundaries.” Ex. 1001, 2:46-58. “Segments are encrypted on segment boundaries
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`
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`using the current content encryption key and current initialization vector (IV). . . .
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`The generation of new strongly random values for use as content encryption keys
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`and the rotation of content encryption keys provides protection from content
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`encryption keys being compromised in long lived streams.” Id., 2:62-3:5.
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`Exemplary claim 1 correspondingly recites:
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`Element Claim 1
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`[1.P]
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`[1.1]
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`A method for handling secure distribution of content comprising:
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`initiating a media playback request and receiving a playback request
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`response;
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`[1.2]
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`parsing content information from the playback request response, the
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`content information including content encryption keys, content
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`encryption key identifiers, and content encryption key expiration
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`times;
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`[1.3]
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`[1.4]
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`retrieving content and manifest files from a content delivery server;
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`detecting content encryption key rotation boundaries between periods
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`of use of different content encryption keys in decrypting retrieved
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`content;
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`[1.5]
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`issuing requests to a license server ahead of a key rotation boundary
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`to retrieve a second content encryption key to be used after a content
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`encryption key rotation boundary is reached; and
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`[1.6]
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`applying the second key for content decryption after the key rotation
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`boundary is reached.
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`The Petition challenges claims 1-20 based on the Grounds below.
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`Ground References
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`Basis Challenged
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`1A
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`1B
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`1C
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`1D
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`1E
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`Claims
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`Peterka, Bocharov
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`§ 103
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`1-4, 6-7, 12-13, 16-20
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`Peterka, Bocharov,
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`§ 103
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`7-9, 14-15, 19
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`Peterka308, Chen
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`Peterka, Bocharov, Balraj
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`§ 103
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`5
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`Peterka, Bocharov, Kelly
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`Peterka, Bocharov, Kelly,
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`§ 103
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`§ 103
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`10
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`11
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`Eisen
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`III. Person of ordinary skill in the art
`For purposes of this Response, Patent Owner does not dispute the Petition’s
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`proposed level of skill for a person of skill in the art (“POSA”), because the level
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`of skill in the art is not necessary for addressing any disputes between the parties.
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`IV. The Petition fails to meet claims 6, 12-15, and 20
`Claim 6 recites the method of claim 4, further comprising “prefetching a
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`next un-retrieved key within a period of time after the expected expiration of the
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`content encryption key currently being applied, the period of time beginning at the
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`expected expiration of the content encryption key currently being used, and
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`ending at a duration calculated as a fixed percentage of a fixed periodic content
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`encryption key expiration interval.” (emphasis added).
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`In its Institution Decision, the Board expressed concern that “prefetching
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`after expiration does not make sense in the context of the ’178 patent.” Paper 11 at
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`26 (emphasis Board’s).
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`Claim 6, however, does not recite prefetching after expiration. Rather, it
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`recites prefetching after “expected expiration of the content encryption key
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`currently being applied,” and giving weight and meaning to the term “expected”
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`and the phrase “currently being applied” is critical to a correct understanding of the
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`claim and the associated teachings of the specification.
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`As the ’178 patent explains, content encryption keys are not necessarily
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`expired at the exact time provided by the workflow manager 102 (WFM 102). Ex.
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`1001 at 8:9-13, 9:1-3. For instance, the ’178 patent teaches that “the fixed duration
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`for key rotation may be viewed as a ‘target’ period, as the packager 104 may not
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`expire a key on the exact boundary,” and “[g]enerally, the packager 104 will not
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`expire a key earlier than the end of a target period.” Id. at 8:9-13 (emphasis
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`added). Thus, the ’178 patent teaches that content encryption keys may be expired
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`at a time that is different than the intended or expected rotation time provided by
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`the WFM 102, and in particular at a time later than the intended or expected
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`rotation time. Id. To the same effect, the ’178 patent teaches that “[t]he key
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`expiration time from the WFM 102 may be viewed as a ‘suggested’ expiration
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`time, as the packager 104 may not be able to expire the key at the exact specified
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`time.” Id. at 9:1-3. Moreover, the ’178 patent further teaches that “if the packager
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`104 is unable to obtain a new content encryption key from the WFM 102 prior to
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`the expiration of the current content encryption key, the packager 104 will continue
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`to use the current content encryption key until such time as it is able to obtain a
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`new key from the WFM 102.” Id. at 6:33-37. Stated otherwise, a content
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`encryption key can remain in use after its expected expiration until the packager
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`104 has obtained a new key from the WFM 102.
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`Claim 6 captures the specification’s above teachings. The term “prefetching”
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`in the context of the claim makes sense as it refers to obtaining a new key before
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`ceasing to use a current key, with the additional nuance that the “prefetching”
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`occurs after the time when the current key was expected to expire.
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`As the Board has already recognized, the Petition’s combination of Peterka
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`
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`and Bocharov does not meet the requirements of claim 6. Paper 11 at 26. Indeed,
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`the Petition asserts that under its combination, “a client device would request a
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`new content encryption key . . . before the expected expiration of the content
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`encryption key currently being applied. . . .” Pet. at 40 (emphasis added). The
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`Petition’s theory is thus exactly the opposite of what claim 6 recites: whereas claim
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`6 requires prefetching a new key after the expected expiration of the current key,
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`the Petition proposes retrieving a new key “before the expected expiration” of the
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`current key. Pet. at 40 (emphasis added). Accordingly, the Petition cannot establish
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`that claim 6 is unpatentable.
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`The Petition likewise fails to establish unpatentability as to claims 12-15 and
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`20, as the Board has also recognized. Paper 11 at 26-27, 29. As the Board correctly
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`found in its Institution Decision, the Petition’s theory as to claims 12-15 and 20
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`“relies on the embodiment disclosed in Peterka wherein a parity bit or other means
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`is used to notify the client that a new encryption key has been sent.” Paper 11 at
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`26. But as the Board has further found, “this embodiment does not teach or suggest
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`the subject matter of claim 1 [and claim 16] because the new keys are not received
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`in response to [a] request from the client for a new key.” Id. at 26; see also id. at 22
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`n. 6. Because claims 12-15 depend from claim 1 and claim 20 depends from claim
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`16, and because Peterka’s parity bit embodiment cannot meet the underlying
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`requirements of claims 1 and 16, the Petition’s reliance on Peterka’s parity bit
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`embodiment also cannot establish unpatentability as to claims 12-15 and 20. Id. at
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`26-27, 29.
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`Accordingly, at least original claims 6, 12-15, and 20 should be upheld.
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`V. The Petition fails to meet limitation 1.4 and 16.5, properly construed, and
`thus fails as to all challenged claims.
`The Board’s Institution Decision correctly found that the Petition’s theory
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`based on Peterka’s use of a predetermined bit to signal encryption key rotation
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`boundaries “is not persuasive because the new keys being signaled are not received
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`in response to request from the client for a new key,” as required by claims 1 and
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`16. Paper 11 at 22 n. 6. The Board likewise correctly declined to consider any
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`theory based on the “combination of the push and pull model” of Peterka, “which
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`was not raised by Petitioner. . . .” Id.
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`Thus, the only theory at issue with respect to claims 1 and 16, and
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`limitations 1.4 and 16.5 in particular, is Peterka’s “pull model,” in which “each
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`client keeps track of the keys and their expiration times and actively requests new
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`keys before the current keys expire. . . .” Paper 11 at 22.
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`As demonstrated below, however, the correct construction of limitations 1.4
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`and 16.5 requires detecting key rotation boundaries before normal period-based
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`expiration, which Peterka’s pull model does not permit. Accordingly, the Petition’s
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`theory based on Peterka’s pull model cannot demonstrate unpatentability as to any
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`challenged claim.
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`A.
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`“[D]etecting content encryption key rotation boundaries between
`periods of use” should be construed to mean detecting key rotation
`boundaries before normal period-based expiration
`As a general rule of claim construction, “all claim terms are presumed to
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`have meaning in a claim.” SIPCO, LLC v. Emerson Elec. Co., 939 F.3d 1301, 1307
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`(Fed. Cir. 2019) (quoting Innova/Pure Water, Inc. v. Safari Water Filtration Sys.,
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`Inc., 381 F.3d 1111, 1119 (Fed. Cir. 2004)). Thus, in SIPCO, the Federal Circuit
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`reversed the Board’s claim construction as unreasonably broad because it failed to
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`give meaning to the term “low-power” in “low-power transceiver.” SIPCO, 939
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`F.3d at 1308. In particular, the Court found that a “low-power transceiver,”
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`understood in view of the specification, was limited to a device with a limited
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`transmission range. Id.
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`Here, the claim language at issue in limitations 1.4 and 16.5 does not simply
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`recite “detecting content encryption key rotation boundaries.” Rather, the relevant
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`claim language recites “detecting content encryption key rotation boundaries
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`between periods of use of different content encryption keys.” Accordingly, a
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`proper construction must give meaning and weight not simply to the requirement
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`of detecting content encryption key boundaries, but more specifically to detecting
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`such rotation boundaries “between periods of use.”
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`As explained in the Preliminary Response, Paper 9 at 11, the ’178 patent
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`teaches two methods by which a current content encryption key can be expired:
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`“normal period-based expiration and an explicit key change notification.” Ex.
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`1001 at 11:4-7 (emphasis added).
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`The ’178 patent consistently uses the phrase “periods of use” to refer to the
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`normal period-based duration of a content encryption key, i.e., the fixed duration
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`lifespan intended for that key as defined by the expiration period set by the WFM
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`102. For instance, the ’178 patent teaches “generating a series of content
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`encryption keys and providing them serially to a packaging server for encrypting a
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`content item, wherein each content encryption key is provided upon expiration of a
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`period of use of a serially preceding content encryption key.” 1:45-50 (emphasis
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`added). In the above teaching, the specification expressly refers to the “expiration”
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`of a “period of use” of a content encryption key, and thus plainly teaches that the
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`phrase “period of use” is synonymous with the normal period-based duration
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`intended for a key, as defined by the expiration period set by the WFM 102.
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`Similarly, the ’178 patent further teaches that “[t]he lifespan of the new content
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`encryption key may be aligned to the periodic use period boundaries of the
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`previous content encryption keys.” Id. at 7:29-31 (emphasis added). The patent
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`thus once again uses the term “periodic use period boundaries” to refer to the
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`normal period-based expiration time of the content encryption key. The ’178 patent
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`likewise teaches “a fixed period duration for key rotation,” id. at 8:7-10 (emphasis
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`added), and “a periodic content encryption key expiration event.” Id. at 8:29-32.
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`Thus, the ’178 patent repeatedly and exclusively uses the term “periods of
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`use” and similar phrases such as “periodic use period boundaries” and “fixed
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`period duration” to refer to the normal period-based expiration of a content
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`encryption key.
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`Given the patent’s consistent usage of “periods of use” and similar phrases
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`to refer to the intended length of the normal period-based duration of an encryption
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`key, it follows that the phrase “between periods of use” as recited in claim 6 must
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`mean an event that occurs during the current use period (or fixed-duration
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`intended lifespan) of a current encryption key. Accordingly, giving meaning to the
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`phrase “between periods of use” as recited in claim 6 requires interpreting
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`limitations 1.4 and 16.5 to require “detecting content encryption key rotation
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`boundaries” that arise during the normal period-based duration of a current key
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`(i.e., before the current key’s period-based rotation boundary would otherwise
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`occur), such as due to an “explicit key change notification.” Ex. 1001 at 11:4-7.
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`That understanding of limitations 1.4 and 16.5 is well-supported by other
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`teachings from the specification. The ’178 Patent teaches that the workflow
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`manager may issue a new unsolicited content encryption key, id. at 7:3-4, which in
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`one embodiment “is pushed ahead of the current content encryption key with
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`explicit instructions to apply the key as soon as possible, in which case the
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`packager 104 does not wait until the current content encryption key has expired
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`before applying the new content encryption key.” Id. at 7:11-16 (emphasis added).
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`The ’178 Patent further explains that the WFM 102 may, for instance,
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`“push[ ] the new content encryption key to the packager 104 when the current
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`content encryption key is deemed to be no longer secure (e.g., if the content
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`encryption key has been compromised).” Id. at 7:17-20.
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`Consistent with the above teachings, Fig. 3 of the Patent (shown below)
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`depicts a flow chart describing a process for detecting the rotation of content
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`encryption keys and retrieving updated content encryption keys.
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`At step 308, “the client 110 checks to see if a key change is signaled, i.e., a
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`key change was requested outside of any fixed duration lifespan.” Id. at 10:39-43
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`(emphasis added). “If a content encryption change request is detected, the client
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`notes the need to expire the current content encryption key and the content
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`encryption key identifier of the new key to be used. The client 110 then proceeds
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`to step 310.” Id. at 10:65-11:2 (emphasis added).
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`“In step 310, the client 110 checks the expiration of current content key to
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`see if a new key should be applied. There are two cases—normal period-based
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`expiration and an explicit key change notification received in step 308 that
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`applies to the current segment being decrypted. If the current content encryption
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`key has not yet expired, processing proceeds to step 314. If the current content
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`encryption key needs to be expired, processing proceeds to step 312 where the key
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`is ‘rotated’, i.e., the current content encryption key is expired and a new one is put
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`into use.” Id., 11:3-12 (emphasis added).
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`Giving proper meaning to the phrase “between periods of use” as recited in
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`claims 1 and 16 and in view of the specification’s relevant teachings thus requires
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`interpreting limitations 1.4 and 16.5 to require detecting whether a key rotation
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`boundary must occur before the time-based expiration of the current key (i.e.,
`
`“between periods of use of different content encryption keys”).
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`By contrast, interpreting the claims to encompass methods or systems that
`
`are incapable of detecting pre-expiration time key rotation boundaries would fail to
`
`give meaning to the phrase “between periods of use,” and would thus be
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`inconsistent with fundamental precepts of claim construction. SIPCO, LLC v.
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` Case IPR2022-00618
`PATENT OWNER’S RESPONSE
`Emerson Elec. Co., 939 F.3d 1301, 1307 (Fed. Cir. 2019) (quoting Innova/Pure
`
`
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`Water, Inc. v. Safari Water Filtration Sys., Inc., 381 F.3d 1111, 1119 (Fed. Cir.
`
`2004)).
`
`B.
`
`Patent Owner’s claim construction is not inconsistent with the
`concerns expressed in the Institution Decision
`Patent Owner recognizes that the Board’s Institution Decision expressed
`
`several concerns with respect to adopting Patent Owner’s proposed construction of
`
`limitations 1.4 and 16.5. Respectfully, however, Patent Owner’s construction is not
`
`inconsistent with the Board’s concerns, as demonstrated below.
`
`First, Patent Owner’s construction does not “limit[] the scope of the claim to
`
`one aspect of the disclosed embodiment of the ’178 patent that deals with the
`
`special case of key changes requested for security reasons outside of any fixed
`
`duration lifespan.” Paper 11 at 20-21. As Patent Owner explained in its
`
`Preliminary Response, limitations 1.5 and 16.6 encompass issuing requests for a
`
`new encryption key due to either (1) normal period-based expiration (i.e., the end
`
`of the current key’s fixed duration lifespan) or (2) a key change instruction
`
`detected by the client in between the current key’s period of use (i.e., before the
`
`current key’s normal period-based expiration). Paper 9 at 15-16. In that respect,
`
`limitations 1.5 and 16.6 thus capture steps 316 and 318 of Fig. 3, which teach that
`
`“[i]f the current content encryption key is within a fixed threshold of expiring or a
`
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`PATENT OWNER’S RESPONSE
`content encryption key change request was detected in step 308, processing
`
`
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`proceeds to step 318 where the client 110 requests a new content encryption key
`
`from the license server 106.” Id. at 11:48-53 (emphasis added).
`
`Thus, Patent Owner’s construction only limits the scope of limitations 1.4
`
`and 16.5, but it does not exclude the embodiment of requesting a new key based on
`
`the normal period-based expiration of the current key from the scope of claims 1
`
`and 16 as a whole.
`
`Stated otherwise, under Patent Owner’s construction claims 1 and 16 cannot
`
`be met where a client cannot detect whether a key rotation boundary has been set
`
`prior to the normal period-based expiration of a current key (i.e., “between periods
`
`of use” as recited in limitation 1.4 and 16.5), but claims 1 and 16 can be met where
`
`a client performs that detection step, concludes that no such pre-period-based
`
`rotation is necessary, and simply requests a new key prior to period-based
`
`expiration of the current key for use after the current key’s period-based expiration
`
`(as covered within the scope of limitations 1.5 and 16.6).
`
`Second, Patent Owner agrees with the Board that “it is the ‘boundaries’ that
`
`are ‘between periods of use of different content encryption keys,’ . . . .” Paper 11
`
`at 21 (emphasis Board’s). That observation is entirely consistent with Patent
`
`Owner’s construction, wherein limitations 1.4 and 16.5 require that the client
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`PATENT OWNER’S RESPONSE
`detect whether there is a key rotation boundary “between periods of use” of current
`
`
`
`keys, i.e., before the normal period-based expiration of a current key.
`
`By contrast, interpreting limitation 1.4 to encompass merely recognizing that
`
`the fixed duration set for a current key is close to expiration would not constitute
`
`detecting a boundary that is “between periods of use of different content
`
`encryption keys,” and would give no meaning to the crucial phrase “between
`
`periods of use,” in violation of the Federal Circuit’s repeated precedents. SIPCO,
`
`LLC v. Emerson Elec. Co., 939 F.3d 1301, 1307 (Fed. Cir. 2019) (quoting
`
`Innova/Pure Water, Inc. v. Safari Water Filtration Sys., Inc., 381 F.3d 1111, 1119
`
`(Fed. Cir. 2004)).
`
`Third, the “detecting” limitation does not correspond to step 316 of Figure
`
`3. Cf. Paper 11 at 21-22. Rather, step 316 corresponds to the next limitation of the
`
`claims (the “issuing requests” limitation, or limitations 1.5 and 16.6). The
`
`specification teaches that: “In step 316, the client 110 checks to see if the current
`
`content encryption key is going to expire in the near future or if a content
`
`encryption key change request for a future segment was detected in step 308.” Ex.
`
`1001 at 11:38-41 (emphasis added). The phrase “was detected” is only used in
`
`reference to a “key change request” requiring rotation of a current key prior to its
`
`normal period-based expiration. Thus, that is the only type of key rotation
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`PATENT OWNER’S RESPONSE
`boundary for which “detection” is taught to occur. Moreover, the use of the past
`
`
`
`tense—“was detected”—teaches that the “detecting” step has already occurred at
`
`step 308, prior to step 316. By contrast, at step 316 the client performs a further
`
`step—checking whether the current key is either set to expire soon or if a change
`
`request was received for key rotation prior to the key’s natural expiration. The
`
`“checking” aspect of step 316 is not expressly recited in any claim limitation, but is
`
`ultimately captured by limitations 1.5 and 16.6, which require issuing a request for
`
`a new key ahead of the rotation boundary of the current key. To that end, the
`
`specification teaches that as part of step 316, “[i]f the current content encryption
`
`key is within a fixed threshold of expiring or a content encryption key change
`
`request was detected in step 308, processing proceeds to step 318 where the client
`
`110 requests a new content encryption key from the license server 106.” Id. at
`
`11:48-53 (emphasis added).
`
`Thus, Patent Owner’s construction is not inconsistent with the Board’s
`
`concerns about reading the teachings of step 316 out of the claims. Rather, Patent
`
`Owner’s construction continues to encompass step 316’s method of proceeding to
`
`step 318, and requesting a new key, regardless of whether the current key is close
`
`to expiration or a key change request “was detected” at step 308, as encompassed
`
`by limitations 1.5 and 16.6.
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`C.
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` Case IPR2022-00618
`PATENT OWNER’S RESPONSE
`The Petition’s theory cannot meet the challenged claims under the
`correct interpretation of limitations 1.4 and 16.51
`It is undisputed that under Peterka’s “pull” embodiment, which is the only
`
`embodiment relevant to this proceeding in view of the Board’s Institution
`
`Decision, the client device does not “detect” any key rotation boundaries prior to
`
`the normal period-based expiration of the current key.
`
`As the Petition itself admits, Peterka’s “pull” embodiment, as disclosed in
`
`Peterka’s paragraphs 105, 106, 114, and its Fig. 8, simply teaches that the client
`
`keeps track of “known key expiry times that allow the client to request new keys
`
`ahead of the expiration or key rotation boundary.” Pet. at 35 (emphasis added).
`
`Peterka’s paragraph 105 further teaches that in its “pull model,” “each client keeps
`
`track of the keys and their expiration times and actively requests new keys before
`
`the current keys expire so as to avoid service interruptions.” Ex. 1004 ¶ 105. The
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`other passages the Petition cites—Peterka’s paragraph 106, 114, and Fig. 8—all
`
`teach the same.
`
`Peterka’s “pull” model does not include the possibility of any key change
`
`notification received by the client ahead of the natural key expiry time of a current
`
`key, nor any other non-time-based key rotation boundary, and there is thus no such
`
`
`1 The Petition solely relies on Peterka as teaching or suggesting limitations 1.4 and
`1.5. Pet. at 34-36.
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`PATENT OWNER’S RESPONSE
`non-time-based key rotation boundary for the client to “detect,” as required in
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`
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`limitations 1.4 and 16.5. To the contrary, Peterka teaches that in its “pull model,”
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`the client makes all key change determinations, entirely based on the expiration
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`time of the current key. Ex. 1004 ¶ 105 (“Under the pull model, each client keeps
`
`track of the keys and their expiration times and actively requests new keys before
`
`current keys expire so as to avoid service interruptions. Alternatively, the push
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`model migrates responsibility to the server which keeps track of active clients and
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`distributes new keys to them before the current keys expire.”); id. ¶ 106
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