TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD.

Patent Trials and Appeals Board

Oct 29, 2021

2020003226 (P.T.A.B. Oct. 29, 2021)

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.
15/441,788 02/24/2017 Shih-Lien Linus LU 4630.0520001 1038
26111 7590 10/29/2021
STERNE, KESSLER, GOLDSTEIN & FOX P.L.L.C.
1100 NEW YORK AVENUE, N.W.
WASHINGTON, DC 20005
EXAMINER
SALMAN, RAIED A
ART UNIT PAPER NUMBER
2495
NOTIFICATION DATE DELIVERY MODE
10/29/2021 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):
e-office@sternekessler.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte SHIH-LIEN LINUS LU
____________

Appeal 2020-003226
Application 15/441,788
Technology Center 2400
____________

Before JEREMY J. CURCURI, NATHAN A. ENGELS, and
AMEE A. SHAH, Administrative Patent Judges.

SHAH, Administrative Patent Judge.

DECISION ON APPEAL

STATEMENT OF THE CASE
Pursuant to 35 U.S.C. § 134(a), the Appellant1 appeals from the
Examiner’s final decision to reject claims 1–3, 5–12, and 14–22.2 We have
jurisdiction under 35 U.S.C. § 6(b).
We REVERSE.

1 We use the word “Appellant” to refer to “applicant” as defined in
37 C.F.R. § 1.42. The Appellant identifies the real party in interest as
“Taiwan Semiconductor Manufacturing Co., LTD.” Appeal Br. 2.
2 The Examiner has withdrawn the prior art rejection of claims 4 and 13.
Ans. 3.
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Application 15/441,788

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CLAIMED SUBJECT MATTER
The Appellant’s invention relates to “SECURE COMMUNICATION
BETWEEN SERVER DEVICE AND CLIENTS UTILIZING STRONG
PHYSICAL UNCLONABLE FUNCTIONS.” Spec., Title (emphasis
omitted).
Claims 1, 10, and 19 are the independent claims on appeal. Claim 1 is
illustrative of the subject matter on appeal and is reproduced below (with
added lettered bracketing for reference):
1. A server device within a client-server device communication
system, the server device comprising:
[(a)] a virtual physical unclonable function (PUF) circuitry
storage device that stores a virtual mapping of a plurality of PUF
circuitries of a plurality client devices within the client-server
device communication system; and
[(b)] encryption circuitry configured to:
[(b1)] query the virtual PUF circuitry storage device
with a first challenge for a first response from among the
virtual mapping corresponding to a client device from
among the plurality of client devices,
[(b2)] generate a second challenge by increasing or
decreasing the first challenge by a challenge coefficient,
and
[(b3)] query the virtual PUF circuitry storage device
with the second challenge for a second response from
among the virtual mapping corresponding to the client
device, and
[(c)] wherein the encryption circuitry comprises:
[(c1)] a first logical gate configured to perform a
logical operation between a first message from among a
plurality of messages and the first response to provide a
first encrypted message, and
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[(c2)] a second logical gate configured to perform
the logical operation between a second message from
among the plurality of messages and the second response
to provide a second encrypted message.
Appeal Br. 20 (Claims App.).

REFERENCES
The prior art references relied upon by the Examiner are:
Name Reference Date
Satoh et al. (“Satoh”) US 2013/0047209 A1 Feb. 21, 2013
Wang et al. (“Wang”) US 2018/0145838 A1 May 24, 2018

THE REJECTION
Claims 1–3, 5–12, and 14–22 stand rejected under 35 U.S.C. § 103 as
unpatentable over Wang and Satoh.

OPINION
We agree with the Appellant that the Examiner does not adequately
show how Wang teaches claim 1’s server device, comprising a virtual
physical unclonable function circuitry storage device (“virtual PUF”) and
encryption circuitries, challenges and uses the responses from the virtual
PUF to encrypt messages. See Appeal Br. 14, 16–17; Reply Br. 2–4.
The Examiner finds that Wang teaches the server device of claim 1
comprising: “a virtual physical unclonable function (PUF) circuitry storage
device that stores a virtual mapping of a plurality of PUF circuitries,” as
recited in limitation (a), and encryption circuitries, as recited in limitations
(b) and (c), comprising the first and second logical gates as configured in
limitations (c1) and (c2). Final Act. 9–11. In the Final Action, the
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Examiner appears to find that Wang’s logical copy of the PUF, PUF
108/208, meets the claimed virtual PUF and Wang’s encryption engine
120/312 meet the claimed encryption circuitries. Id.; Ans. 4. The Examiner
acknowledges that Wang does not teach querying the virtual PUF circuitries
storage device with a first challenge, generating a second challenge, and
querying the virtual PUF circuitries storage device with a second challenge,
as recited in limitations (b1), (b2), and (b3). Final Act. 11. The Examiner
relies on Satoh for curing this deficiency and determines that one of ordinary
skill in the art would modify Wang with Satoh “to create method and
apparatus to authenticate processing, which execute device authentication by
reading parameters recorded in a PUF device using a PUF reader, see
[SATOH: Paragraph 0001: lines 1–4].” Id. at 11–12.
Wang provides for “secure communications using Physical
Unclonable Function (PUF) devices” whereby “[s]egments of a message to
be encrypted are sequentially applied to a PUF device as a series of
challenges to obtain a series of responses for generating a sequence of
encryption keys,” and “whereby a previous segment of the message is used
to obtain a key for encrypting a subsequent segment of the message.” Wang,
Abstr. Wang’s Figure 1 depicts “selected components of a secure
communication system employing a Physical Unclonable Function (PUF)
device for encrypting messages and a logical copy of the PUF for decrypting
messages” (id. ¶ 8), the components including transmit-side device 102,
such as an implantable medical device, that applies a predetermined
challenge 110 to PUF 104 to generate a response 112 that is applied to key
generator 114 to generate key 116 (id. ¶¶ 34, 39). Key 116 and message to
be encrypted 118 are applied to encryption engine 120 to generate encrypted
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message 122. Id. ¶ 34. “Upon receipt of the message, the receive-side
device 106[, such as a health monitoring system,] applies the same challenge
value 110 to the logical copy 108 of the PUF to generate the same response
value 112,” that is then “applied to a key generator 128 (which uses the same
key generation procedures as key generator 114) to generate the
corresponding (same) key 116.” Id. ¶¶ 34, 39. “The key 116 is applied to a
decryption engine 130 along with the received encrypted message 110 to
obtain the (plaintext) message 118.” Id. ¶ 34. “The logical copy 108 of the
PUF may be a set of lookup tables or the like that provides a listing of the
corresponding responses to all permissible challenges for the PUF 104.” Id.
¶ 35. Figure 3 depicts an exemplary transmit-side device 300 “to
sequentially apply segments of a message to a PUF [device 306] to obtain a
sequence of keys, whereby a previous segment of the message is used to
encrypt a subsequent segment of the message,” where a previous message
segment is used to encrypt a subsequent message segment using encryption
engine 312. Id. ¶ 41. For example, “a message (x) 302 to be encrypted is
applied to a serial encoder 304, which may be configured, e.g., to expand a
range of values of the message to more fully exercise a PUF device 306.”
Id. Both the PUF 306 and encryption engine 312 are configured to receive
N-bits in parallel. Id. ¶ 42. “[W]hile an initial N-bit segment of the message
is applied to the PUF 306, a next N-bit segment of the message is applied to
the encryption engine 312.” Id. The key generated by the previous N-bit
segment of the messages is used to encrypt the next N-bit segment of the
message. Id.
As such, Wang teaches that the transmit-side device, i.e., server,
comprises a PUF and encryption engine, whereby the PUF generates a
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response based on a received challenge and the key is used to encrypt a
message, and that the receive-side device comprises a virtual PUF that
obtains the sequence of keys to decrypt the message via a decryption engine.
See Wang ¶¶ 34, 35, 41, 45, Figs. 1, 2; see also Appeal Br. 16–17; Reply
Br. 2–3. However, we interpret the claim as requiring that the virtual PUF
and encryption circuitries are within the same device within a client-server
communication system, i.e., both within either the transmit-side device or
the receive-side device, and that the responses from the virtual PUF are used
to encrypt messages, not decrypt messages. See Appeal Br. 17; Reply
Br. 3–5.
Further, to the extent the Examiner correlates Wang’s PUF 104/204
with the claimed virtual PUF because it ostensibly performs the mapping of
the PUF circuitries (Ans. 6 (explaining that, according to the Appellant’s
Specification, the virtual mapping of responses “is between the physical
PUF and the client device”)), the claim requires a virtual PUF storing the
virtual mapping. See Reply Br. 4. The Examiner does not adequately
explain how Wang teaches PUF 104/204 being a virtual PUF (as opposed to
logical copy of PUF, PUF 108/208) that stores the mapping. To the extent
the Examiner relies on the combination of Wang and Satoh for teaching
querying and receiving responses from the virtual PUF (see Final
Act. 11–12), we note that the Examiner does not explain how Satoh’s PUF
device and reader teach that a virtual PUF is queried and responds, and
whose responses are used to encrypt messages.
Thus, we do not sustain the Examiner’s rejection under 35 U.S.C.
§ 103 of independent claim 1. As the Examiner relies on these findings and
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determinations for claims 2, 3, 5–12, and 14–22 (see Final Act. 12–21;
Ans. 4–9), we also do not sustain the rejection of these claims.
CONCLUSION
The Examiner’s decision to reject claims 1–3, 5–12, and 14–22 is not
sustained.
In summary:
Claim(s)
Rejected
35 U.S.C.
§
Reference(s)/Basis Affirmed Reversed
1–3, 5–12,
14–22
103 Wang, Satoh 1–3, 5–12,
14–22

REVERSED