Ex Parte Wray

Board of Patent Appeals and Interferences

Aug 11, 2008

10202050 (B.P.A.I. Aug. 11, 2008)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte MICHAEL WRAY
____________

Appeal 2008-2326
Application 10/202,050
Technology Center 2100
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Decided: August 11, 2008
____________

Before KENNETH W. HAIRSTON, JOHN A. JEFFERY, and MARC S.
HOFF, Administrative Patent Judges.

JEFFERY, Administrative Patent Judge.

DECISION ON APPEAL
Appellant appeals under 35 U.S.C. § 134 from the Examiner’s
rejection of claims 1-20. We have jurisdiction under 35 U.S.C. § 6(b). We
affirm.

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STATEMENT OF THE CASE
Appellant invented a method for authenticating a user on a computer
network. Specifically, the user is authenticated to a computer on the
network using a password that is unknown to the computer and via a hybrid
protocol over a standard network connection. If the authentication is
accepted, then the computer sends a digital certificate to the user for
subsequent authentication purposes by the user.1 Claim 1 is illustrative:
1. A method for a user to authenticate to a first computer on a
computer network comprises:

a) a user authenticating himself to the first computer with a secret
password unknown to the first computer and by means of a hybrid protocol
over a standard network connection; and

b) if the authentication is accepted, the first computer then sends a
digital certificate to the user, for subsequent use by the user to authenticate
himself by means of the digital certificate to the first computer or other
computers over a standard network connection.

The Examiner relies on the following prior art references to show
unpatentability:
Birrell US 5,805,803 Sep. 8, 1998
Sean Deuby, Windows 2000 Server: Planning and Migration, 1st ed., pp.
82-90, 1999 (“Deuby”).

Jalal Feghhi et al., Digital Certificates: Applied Internet Security, pp. 61-69,
166, 1999 (“Feghhi”).

T. Wu, The SRP Authentication and Key Exchange System (RFC2945), The
Internet Society, Sep. 1, 2000 (“Wu”).

1 See generally Spec. 2:6-5:26.
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Toni Nykänen, Attribute Certificates in X.509, Tik-110.501 Seminar on
Network Security, HUT TML 2000, 2000 (“Nykänen”).

1. Claims 1 and 16 stand rejected under 35 U.S.C. § 103(a) as
unpatentable over Wu and Deuby.
2. Claims 1-20 stand rejected under 35 U.S.C. § 103(a) as unpatentable
over Wu, Birrell, and Feghhi.
3. Claim 11 stands rejected under 35 U.S.C. § 103(a) as unpatentable
over Wu, Birrell, Feghhi, and Nykänen.
Rather than repeat the arguments of Appellant or the Examiner, we
refer to the Briefs and the Answer for their respective details. In this
decision, we have considered only those arguments actually made by
Appellant. Arguments which Appellant could have made but did not make
in the Briefs have not been considered and are deemed to be waived. See 37
C.F.R. § 41.37(c)(1)(vii).

The Obviousness Rejection Over Wu and Deuby
We first consider the Examiner’s obviousness rejection of claims 1
and 16 over Wu and Deuby (Ans. 3-4). Regarding independent claim 1,
Appellant argues that the prior art does not teach or suggest the first
computer sending a digital certificate to the user for subsequent use by the
user for authentication over a standard network connection if authentication
is accepted. Additionally, Appellant argues even if the session ticket of
Deuby is analogous with a digital certificate, it is not sent after the Key
Distribution Center (KDC) accepts user authentication. Rather, Appellant
argues, the KDC sends the session keys to the user responsive to a request,
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and authentication is accepted once the session keys are decrypted by the
client and server and confirmation of such is received. Appellant adds that
the cited prior art fails to disclose user authentication with a secret password
unknown to the first computer as claimed since, among other things, the
KDC in Deuby knows the keys of the client and server (i.e., the first
computer) (App. Br. 6-8). Appellant asserts essentially the same arguments
with respect to independent claim 16 (App. Br. 9-12).
The Examiner indicates that Deuby’s “ticket-granting ticket” (TGT)
corresponds to the recited digital certificate. According to the Examiner,
since the TGT is later sent to the KDC for obtaining a session ticket, it fully
meets the “subsequent use” limitation in step (b) of claim 1 (Ans. 10-12).
The Examiner adds that Wu fully meets the secret password limitation
of step (a) since the first computer in that reference (i.e., the host) knows
only the password verifier (v)—not the password (p). In any event, the
Examiner contends, Deuby also meets this limitation since the KDC knows
only the hash of the user’s password—not the password itself (Ans. 12-13).
Also, the Examiner notes that the client/server connections in the cited prior
art fully meet a “standard network connection” as claimed (Ans. 14).

ISSUE
The issue before us, then, is whether Appellant has shown that the
Examiner erred in finding that the collective teachings of Wu and Deuby
teach or suggest the limitations of independent claims 1 and 16. The issue
turns on whether (1) Deuby’s TGT reasonably corresponds to the recited
digital certificate, and (2) the “first computer” in Wu or Deuby does not
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know the user’s authenticating password. For the following reasons, we find
that no such error has been shown.

FINDINGS OF FACT
1. Wu discloses a network authentication mechanism (Secure Remote
Password (SRP)) that enables negotiating secure connections using a user-
supplied password and secure key exchange (Wu, Abstract). To this end, the
SRP protocol employs a hash function to generate session keys and
authentication proofs. In Wu, the host stores user passwords as triplets that
include (1) the username; (2) the password verifier; and (3) the “salt.”2 (Wu
3:14-25).
2. To authenticate, the client in Wu first sends the username to the
host. In response, the host sends the client the salt stored on the host under
the client’s username. Then, after the client generates a random number that
is used to obtain a result from a particular expression (“A”), the client sends
this result to the host. Upon receipt, the host performs the same process, but
adds the public verifier (v), and then sends this result (from expression “B”)
to the client. Both the client and the host then construct the shared session
key based on their respective formulas (Wu 3:32-4:19).
3. In Wu, constructing the shared session key by both the client and
the host involve each entity determining the result of a particular expression
(“S”)—results that are based in part on the password and password verifier,
respectively. On the client side, “S” is determined based on, among other
things, the values of expression “B” (i.e., received from the host) and value
of expression “x” which is expressed in terms of, among other things, the

2 Wu indicates that the “salt” is expressed as “ = random ( ).” (Wu 3).
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raw password (p) (Wu, 4:8-10 (listing expressions for “x” and “S”)). On the
host side, however, “S” is determined based on a formula which includes the
value of expression “A” (i.e., received from the client). Significantly, unlike
the client, the formula for “S” on the host does not depend on the value of
“x” (which is expressed in terms of the raw password (p)), but rather is
based in part on the password verifier (v). See Wu 4:10 (listing expressions
for “S” for the client and host, respectively).
4. Deuby discloses an authentication protocol, known as “Kerberos,”
that operates with Windows 2000 servers and clients (Deuby 82:10-21,
83:19-22). In a typical implementation, the user at a workstation is
authenticated via a Key Distribution Center (KDC)—a server that essentially
functions as an authentication service for clients using the system (Deuby
84:19-21).
5. One key function of Deuby’s KDC is that it grants “tickets” to
users not only for identification, but also to indicate the permissible range of
activities allowed by the KDC. The KDC can issue various types of tickets,
including session tickets, server tickets, and ticket-granting tickets (TGTs)
(Deuby 84:7-18).
6. A typical example of Deuby’s authentication system is shown in
Figures 3.13 through 3.16. In this example, the user ultimately wants to
access resources on an Exchange server (i.e., the “Brahma” server shown in
Figure 3.14). To this end, the user first must acquire a TGT from the KDC.
Therefore, the user sends an “authentication service request” (i.e., the user’s
hashed password bundled with security information) to the KDC. Upon
receipt, the KDC verifies the user by comparing the password hash to what it
develops from its own copy of the user’s key. If successful, then the KDC
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sends the user a TGT—a ticket that is used to get other tickets (Deuby
84:27-85:8; Fig. 3.13).
7. Once the user in Deuby obtains the TGT, the user can then initiate
the process of accessing the Exchange server. To do this, the user first sends
the TGT and a “ticket-granting service” (TGS) request to the KDC. Upon
receipt, the KDC uses the information in the TGT to construct a “session
ticket” which is sent back to the user. The user then sends the session ticket
to the Exchange server to request access to the requested service. Upon
receipt, the Exchange server opens the session ticket and sets up the session
with the user (Deuby 85:11-88:2; Figs. 3.14-3.16).
8. Birrell discloses a client computer connected to public network
(e.g., the internet). A firewall 130 and a “tunnel” 140 is provided between a
client 110 computer and an intranet 150 with private resources 160 to be
accessed (Birrell, col. 3, ll. 14-20; Fig. 1). The tunnel comprises (1) checker
141; (2) redirector 142; and (3) proxy server 143 that ultimately establish the
requisite connection between the user and the intranet to enable the user to
access the intranet’s private resources.
9. As shown in Figure 3 of Birrell, the client exchanges various
messages between the components of the tunnel to ultimately establish this
connection to the private resources (Birrell, col. 4, ll. 1-64; Figs. 2-3). As
part of this procedure, the checker supplies the client a validation token
299—a token that can be in the form of an X.500 certificate (Birrell, col. 4,
ll. 37-40; Fig. 3 (Step 360)). Upon receipt, the client then sends this token
along with the request for the resource to the proxy server where the token is
validated. If the token is valid, then the proxy server forwards the
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authenticated request to the specified resource inside the firewall (Birrell,
col. 4, ll. 47-54; Fig. 3).
10. Feghhi teaches providing public key information as part of a
digital certificate (Feghhi 68:10-12).

PRINCIPLES OF LAW
In rejecting claims under 35 U.S.C. § 103, it is incumbent upon the
Examiner to establish a factual basis to support the legal conclusion of
obviousness. See In re Fine, 837 F.2d 1071, 1073 (Fed. Cir. 1988). In so
doing, the Examiner must make the factual determinations set forth in
Graham v. John Deere Co., 383 U.S. 1, 17 (1966).
Discussing the question of obviousness of a patent that claims a
combination of known elements, KSR Int’l v. Teleflex, Inc., 127 S. Ct. 1727
(2007), explains:
When a work is available in one field of endeavor, design
incentives and other market forces can prompt variations of it,
either in the same field or a different one. If a person of
ordinary skill can implement a predictable variation, § 103
likely bars its patentability. For the same reason, if a technique
has been used to improve one device, and a person of ordinary
skill in the art would recognize that it would improve similar
devices in the same way, using the technique is obvious unless
its actual application is beyond his or her skill. Sakraida [v. AG
Pro, Inc., 425 U.S. 273 (1976)] and Anderson's-Black Rock[,
Inc. v. Pavement Salvage Co., 396 U.S. 57 (1969)] are
illustrative—a court must ask whether the improvement is more
than the predictable use of prior art elements according to their
established functions.
KSR, 127 S. Ct. at 1740. If the claimed subject matter cannot be fairly
characterized as involving the simple substitution of one known element for
another or the mere application of a known technique to a piece of prior art
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ready for the improvement, a holding of obviousness can be based on a
showing that “there was an apparent reason to combine the known elements
in the fashion claimed.” Id. at 1740-41. Such a showing requires “some
articulated reasoning with some rational underpinning to support the legal
conclusion of obviousness. . . . [H]owever, the 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.” Id. at 1741 (quoting In re
Kahn, 441 F.3d 977, 988 (Fed. Cir. 2006)).
If the Examiner’s burden is met, the burden then shifts to the
Appellant to overcome the prima facie case with argument and/or evidence.
Obviousness is then determined on the basis of the evidence as a whole and
the relative persuasiveness of the arguments. See In re Oetiker, 977 F.2d
1443, 1445 (Fed. Cir. 1992).

ANALYSIS
Based on the functionality of Wu noted in the Findings of Fact section
above, we agree with the Examiner that the host (i.e., the “first computer”)
in Wu’s authentication procedure does not know the user’s password. As
the Examiner indicates (Ans. 13), the host in Wu knows only the password
verifier (v)—not the password (p) itself. This fact is readily apparent from
Page 4 of Wu which shows the stored password verifier (v) at the host and
the raw password (p) at the client.
Furthermore, constructing the shared session key by both the client
and the host in Wu involves each entity determining the result of a particular
expression (“S”)—results that are based in part on the password and
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password verifier, respectively (Findings of Fact (FF) 1-3). Based on this
functionality, we find no error in the Examiner’s position that the host would
not know the user’s password. As indicated above, it is the password
verifier that the host uses in this authentication procedure—not the password
itself.
We also find no error in the Examiner’s reliance on Deuby as teaching
the digital certificate limitation of claims 1 and 16. Based on the function of
the TGT in Deuby’s authentication procedure (FF 4-7), we agree with the
Examiner that the TGT reasonably constitutes a digital certificate that the
user subsequently uses for authentication over a standard network
connection, as claimed. First, the TGT is a digital form of information that
is used not only for identification, but also to indicate the permissible range
of activities allowed by the KDC (FF 5). In this sense, the TGT is said to be
“like a driver’s license” (Deuby 84:7-8) and, as a digital form of information
that is transferred between the KDC and the user, fully meets a “digital
certificate.” Furthermore, the user subsequently uses the TGT for
authentication at least with respect to the KDC (i.e., the “first computer”) in
conjunction with a TGS request as shown in Figure 3.15 (Step 2). The TGT
also effectively authenticates the user with respect to the Exchange server as
well since the user could not access the requested services on the Exchange
server but for the issuance of the TGT. The fact that two authentication
procedures are used in Deuby as Appellant argues (Reply Br. 3) does not
detract from the fact that the TGT is subsequently used by the user for
authentication purposes.
Not only do we find that this functionality in Deuby fully meets the
digital certificate limitation of claims 1 and 16, but we also note that
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Appellant has not persuasively rebutted the Examiner’s position (Ans. 12-
13) regarding the KDC’s functionality with respect to the user’s password.
As we noted previously, the user in Deuby sends an “authentication service
request” in the form of the user’s hashed password bundled with security
information to the KDC which is verified by comparing the password hash
to what the KDC develops from its own copy of the user’s key (FF 6). In
this procedure, the KDC does not use the password itself, but rather the hash
of the password. As such, we find no error in the Examiner’s position that
the KDC does not know the user’s password, but rather the hash of the
password. Lastly, we find that the network connections used in both Wu and
Deuby fully meet a “standard network connection” in view of the scope and
breadth of the limitation.
We therefore find all limitations of claims 1 and 16 fully met by the
collective teachings of Wu and Deuby and the references are reasonably
combinable. We see no reason why Deuby’s teaching of issuing digital
certificates could not be applied upon acceptance of authentication in a
system such as that disclosed by Wu which likewise employs a secure
authentication system. Such a modification, in our view, is tantamount to
the predictable use of prior art elements according to their established
functions -- an obvious improvement. See KSR, 127 S. Ct. at 1740.
For the foregoing reasons, Appellant has not persuaded us of error in
the Examiner’s rejection of independent claims 1 and 16. Therefore, we will
sustain the Examiner’s obviousness rejection of those claims.

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The Obviousness Rejection Over Wu, Birrell, and Feghhi
Claim 1
We now consider the Examiner’s obviousness rejection of claims 1-20
over Wu, Birrell, and Feghhi (Ans. 4-7). Regarding independent claim 1,
Appellant argues that the cited references considered individually and in
combination fail to teach or suggest the limitations of the claim (App. Br.
13-15). The Examiner indicates that not only does Birrell use a standard
network connection, but the reference also teaches issuing a digital
certificate to a user (i.e., via the checker 141) to allow the user to supply
authentication information. This teaching, the Examiner contends, would
have been combinable with Wu’s authentication procedure in light of
Feghhi—a reference that is said to provide the motivation to combine (Ans.
15-18).
The issue before us, then, is whether Appellant has shown that the
Examiner erred in concluding that the limitations of claim 1 would have
been obvious to ordinarily skilled artisans over the collective teachings of
Wu, Birrell, and Feghhi. For the following reasons, we find that no such
error has been shown.
At the outset, our previous discussion with respect to the disclosure of
Wu applies equally here and we therefore incorporate that discussion by
reference. We also find no error in the Examiner’s reliance on Birrell for
teaching a digital certificate as claimed.
In our view, Birrell’s validation token (FF 9) fully meets a digital
certificate as claimed. Not only does Birrell expressly state that the token
can be an X.500 certificate, it is also used by the user for authentication with
respect to the proxy server. We see no reason why this teaching of issuing
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digital certificates could not be applied upon acceptance of authentication in
a system such as that disclosed by Wu which likewise employs a secure
authentication system. Such a modification, in our view, is tantamount to
the predictable use of prior art elements according to their established
functions -- an obvious improvement. See KSR, 127 S. Ct. at 1740.
Furthermore, we find that the connection in Birrell fully meets a “standard
network connection” since both non-secure HTTP and secure HTTPS
protocols are employed (Birrell, col. 3, ll. 5-13; Fig. 1).
Since we find that all limitations of claim 1 are fully met by the
collective teachings of Wu, Birrell, and Feghhi, we find no error in the
Examiner’s obviousness rejection of that claim.

Claims 2-11 and 13-15
Appellant argues claims 2-15, 17, and 18 as a group. Of these claims,
Appellant does not separately argue with particularity the limitations of
claims 2-11 and 13-15 apart from merely asserting that these claims recite
further features and/or combinations of features that are patentably distinct
from the cited prior art (App. Br. 15-16). Such conclusory assertions
without supporting explanation or analysis particularly pointing out errors in
the Examiner’s reasoning fall well short of persuasively rebutting the
Examiner's prima facie case of obviousness. See In re Oetiker, 977 F.2d
1443, 1445 (Fed. Cir. 1992). We therefore sustain the Examiner’s rejection
of claims 2-11 and 13-15 for the reasons indicated previously.

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Claim 12
Appellant, however, does present specific arguments with respect to
claim 12, namely that the prior art fails to teach or suggest that the user is (1)
authenticated initially using a secret password and hybrid protocol, and then
(2) authenticated in a subsequent session using a digital certificate and
public key encryption (App. Br. 16).
However, we agree with the Examiner (Ans. 20) that Wu’s mutual
authentication procedure involves using a secret password and hybrid
protocol, and that Birrell teaches the digital certificate limitation. As we
noted above, we find ample reason to combine these teachings. Moreover,
we note that Feghhi teaches providing public key information as part of a
digital certificate (Feghhi 68:10-12). In light of these collective teachings,
we find no error in the Examiner’s findings that ordinarily skilled artisans
would have employed the recited authentication procedures including using
digital certificates and public key encryption in the subsequent session as
claimed.
For the foregoing reasons, Appellant has not persuaded us of error in
the Examiner’s rejection of claim 12. Therefore, we will sustain the
Examiner’s rejection of that claim.

Claims 17 and 18
Regarding claims 17 and 18, Appellant argues that since Birrell uses
HTTPS communications protocol, it apparently needs an address for the
checker or proxy server to establish the connection. As such, Appellant
contends, the cited prior art fails to teach user authentication without
knowledge of the first computer’s domain name as claimed (App. Br. 16;
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Reply Br. 4). The Examiner, however, notes that nowhere in Wu is there
any disclosure that the user knows the first computer’s domain name in the
authentication process, and, in any event, such knowledge is not required
when communicating with a computer (Ans. 20).
Based on the record before us, we find that Appellant has simply not
shown error in the Examiner’s position—a position that we find reasonable.
First, despite the absence of the computer’s domain name in Wu as noted by
the Examiner, Appellant has not shown that a domain name would
nonetheless be known to the first computer in that system. Appellant has
simply not rebutted the Examiner’s position in this regard.
Nor has Appellant persuasively rebutted the Examiner’s position
regarding domain names not being required for computer communication—a
position that we likewise find reasonable. Appellant’s argument that domain
names are apparently needed in view of the HTTPS protocol used in Birrell
is unsupported by any evidence on this record proving such an assertion.
While we can envision domain names being used in such communications
(e.g., internet-based communications), Appellant has simply not shown why
they would be needed in Birrell. That is, it is equally plausible on the record
before us that such communications would not need domain names, but
rather some alternative form of computer identification could be employed
in lieu of domain names (e.g., numerical addresses or other identifiers).
For the foregoing reasons, Appellant has not persuaded us of error in
the Examiner’s rejection of claims 17 and 18.

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Claim 16
Although Appellant presents separate arguments with respect to the
Examiner's rejection of claim 16 (App. Br. 17-19), we are not persuaded by
these arguments essentially for the reasons we indicated with respect to
claim 1. The rejection of claim 16 over the collective teachings of Wu,
Birrell, and Feghhi is therefore sustained.

Claims 19 and 20
Likewise, since Appellant’s arguments with respect to claims 19 and
20 (App. Br. 19-20) essentially reiterate the same arguments we considered
with respect to claims 17 and 18 above, we will sustain the Examiner’s
rejection of claims 19 and 20 for similar reasons.

The Obviousness Rejection Over Wu, Birrell, Feghhi, and Nykänen
We will also sustain the Examiner's obviousness rejection of claim 11
over the collective teachings of Wu, Birrell, Feghhi, and Nykänen (Ans. 7-
8). Appellant did not present any arguments pertaining to this rejection, let
alone particularly point out errors in the Examiner’s reasoning to
persuasively rebut the Examiner’s prima facie case of obviousness. The
rejection of claim 11 is therefore sustained.

CONCLUSIONS OF LAW
Appellant has not shown that the Examiner erred in finding that the
collective teachings of Wu and Deuby teach or suggest the limitations of
independent claims 1 and 16. Nor has Appellant shown that the Examiner
erred in finding that the collective teachings of Wu, Birrell, and Feghhi teach
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or suggest the limitations of claim 1-20. Also, Appellant has not shown
error in the Examiner’s rejection claim 11 over the collective teachings of
Wu, Birrell, Feghhi, and Nykänen.

DECISION
We have sustained the Examiner's rejections with respect to all claims
on appeal. Therefore, the Examiner’s decision rejecting claims 1-20 is
affirmed.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).

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AFFIRMED

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