Microsoft Technology Licensing, LLC

Patent Trials and Appeals Board

Nov 3, 2020

2019002264 (P.T.A.B. Nov. 3, 2020)

UNITED STATES PATENT AND TRADEMARK OFFICE
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
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
14/561,455 12/05/2014 Seny Fakaba Kamara 332849.02 7041
69316 7590 11/03/2020
MICROSOFT CORPORATION
ONE MICROSOFT WAY
REDMOND, WA 98052
EXAMINER
HAILU, TESHOME
ART UNIT PAPER NUMBER
2434
NOTIFICATION DATE DELIVERY MODE
11/03/2020 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):
chriochs@microsoft.com
usdocket@microsoft.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte SENY FAKABA KAMARA and
CHARALAMPOS PAPAMANTHOU
Appeal 2019-002264
Application 14/561,455
Technology Center 2400
Before MAHSHID D. SAADAT, ST. JOHN COURTENAY III, and
ELENI MANTIS MERCADER, Administrative Patent Judges.
MANTIS MERCADER, Administrative Patent Judge.
DECISION ON APPEAL
STATEMENT OF THE CASE
Pursuant to 35 U.S.C. § 134(a), Appellant1 appeals from the
Examiner’s decision to reject claims 21–38, 39 and 41. Claims 1–20 and 40
are canceled. See Final Act. 1. We have jurisdiction under 35 U.S.C. § 6(b).
We REVERSE.

1 We use the term “Appellant” to refer to “applicant” as defined in 37 C.F.R.
§ 1.42. Appellant identifies the real party in interest as Microsoft
Technology Licensing, LLC, the owner of the application. Appeal Br. 2.
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Application 14/561,455
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CLAIMED SUBJECT MATTER
The claims are directed to a dynamic symmetric searchable
encryption. Claim 21, reproduced below, is illustrative of the claimed
subject matter:
21. A method executed at a server computing device, the
method comprising:
storing ciphertexts in a data repository, the ciphertexts
being encryptions of files;
storing an encrypted index in the data repository of the
server computing device, the encrypted index being an
encryption of an index that indexes the files by words included
in the files, wherein an entirety of the index is encrypted using
an encryption key to generate the encrypted index;
receiving, from a client computing device, a new
ciphertext that is to be added to the ciphertexts, the new
ciphertext being an encryption of a new file; and
updating the encrypted index to reflect addition of the new
ciphertext to the ciphertexts, wherein updating of the encrypted
index is performed without decrypting the encrypted index to
acquire the index.
REFERENCES
The prior art relied upon by the Examiner is:
Name Reference Date
Travison, Jr. US 2007/0112795 A1 May 17, 2007
So US 2007/0277005 A1 Nov. 29, 2007
Lei US 2009/0300351 A1 Dec. 3, 2009
Briceno US 8,281,125 B1 Oct. 2, 2012

REJECTIONS
Claims 21, 22, 24, 26–31, and 34–41 are rejected under 35 U.S.C.
§ 103(a) as being unpatentable over Lei (US Pub. No. 2009/0300351) in
view of So (US Pub. No. 2007/0277005). Final Act. 4.
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Application 14/561,455
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Claims 23, 32, and 33 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Lei (US Pub. No. 2009/0300351) in view of So (US Pub.
No. 2007/0277005), and further in view of Travison (US Pub. No.
2007/0112795). Final Act. 15.
Claim 25 is rejected under 35 U.S.C. § 103(a) as being unpatentable
over Lei (US Pub. No. 2009/0300351) in view of So (US Pub. No.
2007/0277005) and further in view of Briceno (US 8,281,125). Final Act.
15.

Claim(s) Rejected 35 U.S.C. § Reference(s)/Basis
21, 22, 24, 26–31,
34–41
103(a) Lei, So
23, 32–33 103(a) Lei, So, Travison
25 103(a) Lei, So, Briceno

OPINION
The Examiner finds that Lei, teaches enabling content-based search on
encrypted files, wherein the data owner generates an encrypted index
according to each keyword of the files and stores the encrypted index to the
server. Final Act. 2 (citing Lei ¶ 51); Ans. 15. The Examiner finds that
according to Lei, the data owner encrypts the files and stores the encrypted
files in the server and generates an encrypted index based on keywords of
the files (i.e., words included in the files) and stores them in the server. Id.
The Examiner further finds that Lei teaches that the encrypted index
may be easily updated in the case of adding one or more files later. Final
Act. 3 (citing Lei ¶ 125). Lei teaches for example, if the data owner adds an
additional encrypted file to the storage service sometime after the encrypted
index has been established, the data owner terminal may simply compute the
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Keyword Item Sets (i.e., KIS) locators and the file locators (accompanied
with or without index locators) in association with the newly added file and
transmit them to the server. Id. The Examiner finds that at the server, the
index search unit locates the KISes corresponding to the received KIS
locators, and the index update unit updates the encrypted index by simply
adding the received file locators (accompanied with or without index
locators) in the corresponding KISes. Id. The Examiner concludes that the
information of the added file is incorporated in the updated index. Id. The
Examiner further finds that Lei teaches that the extended file locator
decryption key is kept secret at respective searcher and will not revealed to
the server. Id. (citing Lei ¶ 132)
The Examiner also finds that Lei fails to teach the method of
encrypting the entirety index but relies on So for this teaching. Ans. 15
(citing So ¶¶93 and 147). The Examiner finds that So teaches that the
invention is effective even if some or whole of the contents file or index file
is encrypted. Ans. 16 (citing ¶147).
Appellant argues inter alia that the index of Lei is able to operate in a
desired manner because the index described in Lei is composed of separately
and independently encrypted entries. Reply Br. 3; see also App. Br. 9-10
(citing Lei ¶¶ 66, 68, 74, and 125). Appellant explains that, the ability in Lei
to add a new entry to the index without decrypting some other existing entry
in the index is due to each entry in the index being separately and
independently encrypted. Id. Appellant argues that if Lei were modified
with the teachings of So, the resultant encrypted index would not be able to
be updated without first decrypting the encrypted index, thereby frustrating
the purpose of Lei. Id. Appellant argues that because the proposed
modification of Lei renders Lei inoperable for its intended purpose, the
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Examiner is in error when modifying the teaching of Lei with So’s teaching.
Id.
We agree with Appellant that the index of Lei is able to operate in a
desired manner because the index described in Lei is composed of separately
and independently encrypted entries. See Reply Br. 3; see also App. Br. 9-
10 (citing Lei ¶¶ 66, 68, 74, and 125). We further agree with Appellant that,
the ability in Lei to add a new entry to the index without decrypting some
other existing entry in the index is due to each entry in the index being
separately and independently encrypted. Id. We further agree with
Appellant that if Lei were modified with the teachings of So, the resultant
encrypted index would not be able to be updated without first decrypting the
encrypted index, thereby frustrating the purpose of Lei. Id.
Because Lei teaches encrypting separate and independent entries, and
thus Lei teaches using multiple keys, Lei does not teach “an entirety of the
index is encrypted using an encryption key to generate the encrypted index”,
but rather multiple separate keys are used for each entry. See Lei’s paras. 68
and 125. Furthermore, we agree with Appellant that for the entirety of the
index to be encrypted, as taught by So, another encryption level would be
involved and thus, decryption of the entirety of the index would be needed
thereby not meeting the limitation of “updating of the encrypted index is
performed without decrypting the encrypted index to acquire the index” as
recited in claim 21. See So’s ¶ 147. While the Examiner relies on Lei for
teaching the limitation of “updating of the encrypted index is performed
without decrypting the encrypted index to acquire the index”, in the context
of Lei that can be done because of the separate encrypted key entries, if
modified by So as suggested by the Examiner to encrypt the entirety of the
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list to an encrypted list another level of encryption would be introduced
requiring decryption of the list for further addition of other entries.
Accordingly, we agree with Appellant that the neither Lei nor So nor
their combination teaches or suggest the limitations of “wherein an entirety
of the index is encrypted using an encryption key to generate the encrypted
index” and “wherein updating of the encrypted index is performed without
decrypting the encrypted index to acquire the index” as recited in claim 21.
CONCLUSION
We reverse the Examiner’s rejections under 35 U.S.C. § 103(a) of all
claims 21–38, 39, and 41 on appeal.
DECISION SUMMARY
Claim(s)
Rejected
35 U.S.C. § Reference(s)/Basis Affirmed Reversed
21, 22, 24,
26–31,
34– 41
103(a) Lei, So 21, 22, 24,
26–31,
34– 41
23, 32, 33 103(a) Lei, So, Travison 23, 32, 33
25 103(a) Lei, So, Briceno 25
Overall
Outcome
21–39, and
41

REVERSED