Ex Parte Tang et al

Patent Trials and Appeals Board

Jan 30, 2019

13301219 - (D) (P.T.A.B. Jan. 30, 2019)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
13/301,219 11/21/2011
16000 7590 02/01/2019
Comcast
c/o Ballard Spahr LLP
999 Peachtree Street, Suite 1000
Atlanta, GA 30309
FIRST NAMED INVENTOR
Lawrence Tang
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www .uspto.gov
ATTORNEY DOCKET NO. CONFIRMATION NO.
26141.0014Ul 2154
EXAMINER
TRAN, TONGOC
ART UNIT PAPER NUMBER
2434
NOTIFICATION DATE DELIVERY MODE
02/01/2019 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
USpatentmail@ballardspahr.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte LAWRENCE TANG, KENNETH P. MILLER, and
CHRISTOPHER J. BENNETT
Appeal 2018-004968
Application 13/301,219 1
Technology Center 2400
Before CARLA M. KRIVAK, JASON V. MORGAN, and
PHILLIP A. BENNETT, Administrative Patent Judges.
BENNETT, Administrative Patent Judge.
DECISION ON APPEAL
STATEMENT OF THE CASE
Appellants appeal under 35 U.S.C. § 134(a) from the Examiner's final
rejection of claims 1-20. We have jurisdiction under 35 U.S.C. § 6(b ).
We affirm.
1 Appellants' Brief ("App. Br.") identifies Comcast Cable Communications,
LLC as the real party in interest. App. Br. 1.
Appeal2018-004968
Application 13/301,219
CLAIMED SUBJECT MATTER
The claims are directed to authenticating data by generating a nonce
based upon a shared key. Spec. ,r 91. The shared key and nonce may then
be transmitted to a recipient device as an encrypted authentication data block
while minimizing bandwidth. Id. Claims 1, 9, and 17 are independent
claims and are reproduced below:
1. A method comprising:
processing, by a computing device, a first secret element
based upon an intended recipient device to generate a first
encrypted secret element;
processing, by the computing device, a second secret
element to generate a non-secret element, the second secret
element being distinct from the first secret element; and
processing, by the computing device, the first encrypted
secret element and the non-secret element to generate an
encrypted data block, wherein the encrypted data block
comprises the first encrypted secret element and the non-secret
element.
App. Br. 12 (Claims Appendix).
9. A method comprising:
encrypting, by a computing device, a first shared key
based upon a first intended recipient device to generate an
encrypted first shared key;
encrypting, by the computing device, a second shared key
based upon a second intended recipient device to generate an
encrypted second shared key, the second shared key being
distinct from the first shared key;
processing, by the computing device, the second shared
key to generate a non-secret element; and
processing, by the computing device, the first encrypted
shared key, the second encrypted shared key, and the non-secret
element to generate an encrypted data block.
App. Br. 13 (Claims Appendix).
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Application 13/301,219
1 7. A method comprising:
processing, by a computing device, a data block to
determine a shared key nonce;
processing, by the computing device, the data block to
determine a shared key associated with a first identifier, wherein
the data block comprises a plurality of encrypted shared keys,
and wherein each of the plurality of encrypted shared keys is
encrypted based upon a distinct one of a corresponding plurality
of intended recipient devices;
generating a first authentication key based upon the shared
key;
generating an authentication nonce using the first
authentication key; and
comparing the authentication nonce to the shared key
nonce to determine authentication.
App. Br. 14 (Claims Appendix).
REFERENCES
The prior art relied upon by the Examiner in rejecting the claims on
appeal is:
Kruglick
Engels
Liu
Kocher et al.
US 2011/0307953 Al
US 2012/0011360 Al
US 2013/0024689 Al
US 8,386,800 B2
REJECTIONS
Dec. 15, 2011
Jan. 12,2012
Jan.24,2013
Feb.26,2013
Claims 1-17 and 20 stand rejected under 35 U.S.C. § I03(a) as being
unpatentable over Kocher, Kruglick, and Liu. Final Act. 3-11.
Claims 18 and 19 stand rejected under 35 U.S.C. § I03(a) as being
unpatentable over Kocher, Kruglick, Liu, and Engels. Final Act. 11-12.
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Application 13/301,219
ANALYSIS
We have reviewed the Examiner's rejections in light of Appellants'
arguments set forth in the Appeal Brief and the Reply Brief. We are not
persuaded by Appellants' arguments. We adopt as our own: (1) the findings
and reasons set forth by the Examiner in the action from which this appeal is
taken (Final Act. 2-12) and (2) the findings, reasons, and explanations set
forth by the Examiner in the Examiner's Answer in response to Appellants'
Brief (Ans. 3-24) and concur with the conclusions reached by the Examiner.
We highlight the following for emphasis.
Claim 1
In rejecting claim 1, the Examiner finds that Kocher teaches
"processing ... a first secret element to generate a first encrypted secret
element" because it describes using a shared secret key KRoorwhich can be
used to generate encrypted information. Final Act. 3--4 ( citing Kocher col.
6, 11. 4--18). The Examiner further finds Kocher teaches "processing ... a
second secret element to generate a non-secret element, the second secret
element being distinct from the first secret element." Final Act 4 ( citing
Kocher col. 8, 11. 18-31 ); Ans. 15-16 ( citing Kocher col. 3, 11. 20-24 ). The
Examiner acknowledges that Kocher does not teach "the encrypted data
block comprises the first encrypted secret element and the non-secret
element," and turns to Kruglick for teaching generating encrypted data
blocks comprising a secret node key and a non-secret nonce. Final Act 4
( citing Kruglick ,r 45); Ans. 17. The Examiner finds "it would have been
obvious to implement Kruglick's teaching with Kocher's key to ensure the
key is protected." Ans. 17. The Examiner also acknowledges Kocher does
not teach that the first secret element is "based upon an intended recipient
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Application 13/301,219
device." For this limitation, the Examiner cites Liu, and states that "[i]t
would have been obvious to one of ordinary skill in the art at the time the
invention was made to implement Liu's feature with Kocher's generation of
secret key to enable the client device to decrypt the protected content at the
client device." Final Act. 4 ( citing Liu ,r 7).
Appellants argue the cited combination fails to teach the limitation of
"the second secret element being distinct from the first secret element."
App. Br. 4--5. Specifically, Appellants argue Kocher teaches a system in
which both an encrypting device and a decrypting device has access to the
same shared key (KRoor), and as a result, cannot disclose distinct first and
second elements. Id.
We do not find this argument persuasive. 2 As explained by the
Examiner, Kocher teaches that a different key should be used for each
segment of data to be encrypted. Ans. 16 (citing Kocher col. 3, 11. 21-25).
In so doing, Kocher's encryption technique generates a first encrypted secret
element from a first secret element (KRoor) and a non-secret element (nonce
N) by "deriving N from keys." See Kocher col. 8, 11. 24--26. Although
Appellants argue that "Kocher is silent as to any of these keys being 'based
upon an intended recipient device"' (Reply Br. 1 ), this argument is not
persuasive because the Examiner cites Liu for this limitation, and not
Kocher. See Final Act. 4 ( citing Liu ,r 7).
Appellants further argue the cited combination does not teach the
limitation "to generate an encrypted data block, wherein the encrypted data
block comprises the first encrypted secret element and the non-secret
2 Appellants present a substantively similar argument with respect to
claim 9, which we also do not find persuasive for the same reasons.
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Application 13/301,219
element." App. Br. 5---6. Specifically, Appellants argue the Examiner's
reliance on Kruglick is misplaced because it "simply discloses encrypting a
message that includes two items of information, and fails to disclose
generating an encrypted data block that comprises a first encrypted secret
element and a non-secret element, as recited in claim 1." App. Br. 6. We
disagree.
As the Examiner explains, Kruglick demonstrates that it was known to
generate encrypted data blocks comprising a secret node key (i.e., a "first
encrypted secret element") and a nonce (i.e., a "non-secret element"). 3 Final
Act 4 ( citing Kruglick ,r 45); Ans. 17. We agree with the Examiner that
Kruglick teaches this feature because Kruglick states that "the secure pairing
module 130 can be configured to use the shared signal signature vector to
encrypt a node key and a nonce to create a confirmation message to securely
exchange a key with another node." Kruglick ,r 45.
Claim 15
Appellants also present arguments for dependent claim 15, which
includes the limitation "wherein the second shared key is associated with a
second class of recipient device, different from the first class of recipient
devices." App. Br. 7. The Examiner finds Kocher and Liu teach this
limitation. Final Act. 9 (citing Kocher col. 11, 11. 1-5); Ans. 20 (citing Liu's
use of a key derived from device information such as device serial numbers
to allow specific devices to access a specific content).
3 We note that the Specification indicates that a nonce is a non-secret value.
See Spec ,r 64 ("In an aspect, the first shared key nonce 324 can comprise a
non-secret value associated with a shared key, such as the first shared key
320 and used to authenticate possession of the shared key.")
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Appellants argue Kocher is deficient because "[t]he cited portions of
Kocher discuss the possibility of using different instances of a message key
KMESSAGE- These instances of KMESSAGE are based on the same shared key
KRooT, but are not shared themselves." App. Br. 7. Appellants further
contend Liu is deficient because it "is silent as to the 'content key' being a
'shared key' as claimed ... [because] a key based on a 'serial number'
would not be associated with a 'class of recipient device[s]' as claimed."
Reply Br. 3.
We are not persuaded by Appellants' arguments. The disputed
limitation in claim 15 recites "wherein the second shared key is associated
with a second class of recipient device, different from the first class of
recipient devices." App. Br. 13 (Claims Appendix) (emphasis added). As
explained by the Examiner in the Answer, Kocher teaches that different
shared keys can be derived from different values. Liu teaches that it was
generally known to encrypt a content key based on values derived from
recipient device information, and provides a device serial number as a
specific example of doing so. Liu ,r 15. Although Liu does not explicitly
teach that a device serial number is indicative of a class of devices, we agree
with the Examiner that it would have been obvious to a person of skill in the
art to use other values derived from recipient device information, such as a
model number indicative of a class of devices, to encrypt a content key.
KSR Int'! v. Teleflex Inc., 550 U.S. 398,418 (2007) ("the [obviousness]
analysis need not seek out precise teachings directed to the specific subject
matter of the challenged claim, for a court can take account of the inferences
and creative steps that a person of ordinary skill in the art would employ").
As such, we agree with the Examiner that the combined teachings of Kocher
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and Liu at least suggest the argued limitation in claim 15, and we therefore
sustain its rejection.
Claim 17
Independent claim 1 7 is argued separately by Appellants. Appellants
challenge the Examiner's conclusion of obviousness with respect to the
limitation of "processing, by the computing device, the data block to
determine a shared key associated with a first identifier, wherein the data
block comprises a plurality of encrypted shared keys, and wherein each of
the plurality of encrypted shared keys is encrypted based upon a distinct one
of a corresponding plurality of intended recipient devices." The Examiner
relies on the combined teachings of Kocher, Kruglick, and Liu for this
limitation. Final Act. 9--11.
Appellants offer three arguments for patentability of claim 1 7. First,
Appellants argue Kruglick is deficient because it "discloses that the
confirmation message includes a single key, not a plurality of keys." App.
Br. 8. Second, Appellants argue that because Kruglick "teaches that the
node key is a signal signature vector, but fails to disclose any encryption
applied to the signal signature vector," it does not teach "a data block that
comprises a plurality of encrypted shared keys." Id. Third, Appellants
argue Kruglick "fails to disclose or suggest that each of the plurality of
encrypted shared keys is encrypted based upon a distinct one of a
corresponding plurality of intended recipient devices." Id.
We are not persuaded by Appellants' arguments. With respect to
Appellants' argument that Kruglick fails to teach a plurality of encrypted
shared keys, we note the Examiner cites Kocher as teaching the plurality of
shared keys, and relies on Kruglick as teaching encrypting shared keys.
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Final Act. 10 (citing Kocher Fig. 6, item 650 and Fig. 5, 505-508; Kruglick
,r 45). Thus, the Examiner relies on the combined teachings of the
references to show obviousness of this limitation. Appellants' argument
attacks Kruglick singly as failing to teach the recited "plurality," but does
not address the findings of the Examiner that relies on Kocher as teaching
the recited "plurality." As such, this argument is not persuasive of Examiner
error.
We also are not persuaded by Appellants' second argument that
Kruglick "teaches that the node key is a signal signature vector, but fails to
disclose any encryption applied to the signal signature vector" and does not
teach "a data block that comprises a plurality of encrypted shared keys." We
first note Kruglick teaches that the "shared signal signature vector" is used
"to encrypt a node key and a nonce to create a confirmation message."
Kruglick ,r 45. In light of this disclosure, we disagree with Appellant that
Kruglick does not disclose encryption applied to the node key to create an
encrypted data block. Moreover, as we stated above, the Examiner does not
rely on Kruglick as teaching the "plurality," but instead relies on Kocher for
this aspect of the claim. Accordingly, we find Appellants' second argument
unpersuasive of Examiner error.
Appellants' third argument is unpersuasive because the Examiner
relies on Liu, and not Kruglick, for disclosing "based upon a distinct one of
a corresponding plurality of intended recipient devices." Final Act. 11
( citing Liu ,r,r 7, 29). Accordingly, we are not persuaded the Examiner erred
in rejecting claim 17, and we sustain its rejection under 35 U.S.C. § 103(a).
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Rationale for Combining References
Appellants also attack the combination of Kocher and Kruglick,
asserting that the proposed modification of Kocher with the teachings of
Kruglick would change the principle of operation of Kocher. Particularly,
Appellants argue Kocher teaches the use of a shared key which allows for
transmission of encrypted messages without the need to pass a key between
devices. Appellants assert Kruglick teaches passing the node key as part of
a confirmation message, which undermines Kocher' s ability to transmit a
message without key exchange. App. Br. 9.
We do not find this argument persuasive. The Examiner relies on
Kruglick only to show that it was known to generate encrypted data blocks
that include secret and non-secret elements. As the Examiner finds,
Kruglick "is used to introduce a well-known feature of keeping a secret
information safe." Ans. 23. Moreover, Appellants do not identify any
portion of Kocher which disparages or otherwise discredits transmission of
encrypted keys between devices. Accordingly, we are not persuaded the
Examiner erred in combining Kocher and Kruglick.
DECISION
Because we do not find Appellants arguments persuasive, we affirm
the Examiner's rejection of claims 1-20.
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No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a). See 37 C.F.R.
§ 1.136(a)(l )(iv).
AFFIRMED
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