Ex Parte Proudler

Board of Patent Appeals and Interferences

Oct 25, 2011

10688397 (B.P.A.I. Oct. 25, 2011)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte GRAEME JOHN PROUDLER

___________

Appeal 2009-012007
Application 10/688,397
Technology Center 2400
____________

Before ALLEN R. MACDONALD, JASON V. MORGAN, and
ERIC B. CHEN, Administrative Patent Judges.

CHEN, Administrative Patent Judge.

DECISION ON APPEAL

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This is an appeal under 35 U.S.C. § 134(a) from the final rejection of
claims 35-42, 44 and 46-49. Claims 1-34, 43 and 45 have been cancelled.
We have jurisdiction under 35 U.S.C. § 6(b). We affirm.
Appellant’s invention relates to an access-control arrangement for
handling a tree-structured hierarchy such as a key hierarchy. (Spec.
Abstract.)
Claim 35 is exemplary, with disputed limitations in italics:
35. A computing platform comprising:
a secure key-handling unit arranged to store a storage root key
that forms the root node of a tree-structured node hierarchy the non-
leaf nodes of which, other than the root node, each comprise, in
encrypted form, a key used to encrypt the or each of its child nodes,
and
insecure storage for storing the hierarchy nodes other than the
root node;
the key-handling unit comprising:
a memory for storing a current decryption-root key;
a decrypted-access arrangement arranged to restrict decrypted
access to the hierarchy nodes to those nodes decryptable by a chain of
decryption rooted in said current decryption-root key; and
a current-decryption-root setting arrangement for storing in
said memory, in decrypted form, the key of a selected non-leaf node
of said hierarchy to serve as said current decryption-root key, the
current-decryption-root setting arrangement enabling the selected non-
leaf node to be changed.
Claims 35-42, 44 and 46-49 stand rejected under 35 U.S.C. § 103(a)
as being obvious over Challener (U.S. Patent Application Publication No.
2002/0059286) and Ishiguro (U.S. Patent No. 5,796,839).
We are not persuaded by Appellant’s arguments (App. Br. 5-6; see
also Reply Br. 2-3) that the combination of Challener and Ishiguro would
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not have rendered obvious independent claim 35, including the disputed
limitation “a decrypted-access arrangement arranged to restrict decrypted
access to the hierarchy nodes to those nodes decryptable by a chain of
decryption rooted in said current decryption-root key.”
The Examiner found that the trusted platform module chip (TPM) of
Challener including a storage root key 101 corresponds to this disputed
limitation. (Ans. 3, 7-8.) In particular, the Examiner found that “Challener
explicitly discloses a decrypted access arrangement (i.e. the storage root key
being used to decrypt all leaf nodes below it).” (Ans. 8; Challener,
¶ [0021].) We agree with the Examiner.
Challener describes a typical design of a trusted platform module chip
(TPM) that includes “a storage root key 101, which would have a platform
migratable key 102, which would also have a user key 103, which would
then have signing keys 104-106.” (¶ [0021]; fig. 1.) The storage root
key 101 is used to store other keys (i.e., children keys), such that the chip
decrypts these other keys. (¶ [0021].) In other words, Challener teaches the
limitation “a decrypted-access arrangement arranged to restrict decrypted
access to the hierarchy nodes to those nodes decryptable by a chain of
decryption rooted in said current decryption-root key.”
Appellant argues that:
[T]he only “current decryption-root key” disclosed in Challener is the
storage root key itself and all the hierarchy nodes are decryptable by a
chain of decryption rooted in the storage root key – therefore there is
no concept of less than the whole hierarchy being decryptable in
Challener and therefore no concept of an arrangement restricting
decrypted access to a subset of the nodes of the hierarchy.
(App. Br. 6.)
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However, this argument is not commensurate in scope with claim 35
because the claim does not require that only a subset of the whole hierarchy
nodes be decryptable.
Therefore, we agree with the Examiner that the combination of
Challener and Ishiguro would have rendered obvious independent claim 35,
including the disputed limitation “a decrypted-access arrangement arranged
to restrict decrypted access to the hierarchy nodes to those nodes decryptable
by a chain of decryption rooted in said current decryption-root key.”
We are also not persuaded by Appellant’s arguments (App. Br. 8-11;
see also Reply Br. 4) that the combination of Challener and Ishiguro would
not have rendered obvious independent claim 35, including the disputed
limitation “a current-decryption-root setting arrangement.”
The Examiner acknowledged that Challener does not disclose the
second disputed limitation and therefore cited Ishiguro. (Ans. 3-4.) In
particular, the Examiner found that the disclosure in Ishiguro of selecting an
encryption key of a proper generation from hierarchized keys corresponds to
this disputed limitation. (Ans. 9.) The Examiner concluded that “it would
have been obvious . . . to modify the teachings of Challener by the current
decryption-root arrangement as taught by Ishiguro to provide a decoding
apparatus in which encryption keys can be managed with ease.” (Ans. 4.)
We agree with the Examiner.
As discussed previously, Challener describes a trusted platform
module chip (TPM). (¶ [0021].) Ishiguro relates to the encryption of
software or data (col. 1, ll. 8-14) (e.g., encrypted software or data recorded
on a digital video disk (col. 1, ll. 24-29)). Ishiguro describes that each time
an encryption key is updated, the previous encryption key is retained such
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that “the hardware and the software both face problems of managing the
retained encryption keys” (col. 1, ll. 59-67) and thus, “it is an object of the
present invention to provide an encryption method . . . in which encryption
keys can be managed with ease by hierarchizing encryption keys” (col. 2,
ll. 6-11). Ishiguro describes a master key read out from a memory 12 of an
IC chip 11 and set to a selection key (k) that is supplied to a decoding
circuit 14, such that the selection key (k) is expressed as an encryption key.
(Col. 6, ll. 29-34.) In other words, Ishiguro teaches the limitation “a current-
decryption-root setting arrangement.”1
A person of ordinary skill in the art at the time of the invention would
have recognized that incorporating the master key and the selection key (k)
of Ishiguro, with the trusted platform module chip (TPM) of Challener
would improve Challener by facilitating the management of encryption keys.
See KSR Int’l Co. v. Teleflex, Inc., 550 U.S. 398, 417 (2007). Thus, we
agree with the Examiner (Ans. 4) that modifying Challener to include the
master key and the selection key (k) of Ishiguro would have been obvious.
Appellant argues that “Ishiguru has no concept of an arrangement for
restricting access to only some of the hierarchy nodes because Ishiguru
always starts with the available key that is highest up the hierarchy.” (App.
Br. 9.) Again, this argument is not commensurate in scope with claim 35
because the claim does not require restricting access to only some of the
hierarchy nodes.

1 Appellant also admits that “we agree that Ishiguro discloses the current-
decryption-root setting arrangement” and “Ishiguro must also implicitly
have a memory for storing the key acting as the current decryption root
key.” (App. Br. 8.)
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Appellant also argues that “[t]he Examiner has provided no articulated
reasoning with some rational underpinning to support his legal conclusion of
obviousness” because “the required security properties of the Challener
TPM make it highly undesirable that the keys of its key hierarchy are
cryptographically related to each other as in Ishiguro.” (App. Br. 11; see
also Reply Br. 4.) However, as discussed previously, the combination of
Challener and Ishiguro is based on the improvement of a similar device in
the same way as in the prior art. Furthermore, Appellant has not provided
any persuasive evidence to support the argument that the TPM of Challener
and the encryption keys of Ishiguro are incompatible. Arguments of counsel
cannot take the place of factually supported objective evidence. See, e.g.,
In re Huang, 100 F.3d 135, 139-140 (Fed. Cir. 1996).
Therefore, we agree with the Examiner that the combination of
Challener and Ishiguro would have rendered obvious independent claim 35,
including the disputed limitation “a current-decryption-root setting
arrangement.”
Accordingly, we sustain the rejection of independent claim 35 under
35 U.S.C. § 103(a). Claims 36-42, 44 and 46-49 depend from independent
claim 35 and Appellant has not presented any substantive arguments with
respect to these claims. Therefore, we sustain the rejection of claims 36-42,
44 and 46-49 under 35 U.S.C. § 103(a) for the same reasons discussed with
respect to independent claim 35.
DECISION
The Examiner’s decision to reject claims 35-42, 44 and 46-49 is
affirmed.
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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)(1)(iv).

AFFIRMED

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