Data Encryption Corporation v. Microsoft Corporation

NOTE: This disposition is nonprecedential.
United States Court of Appeals for the Federal Circuit
2006-1603
DATA ENCRYPTION CORPORATION,
Plaintiff/Counterclaim Defendant-
Appellant,
v.
MICROSOFT CORPORATION,
Defendant/Counterclaimant-Appellee,
and
DELL COMPUTER CORPORATION,
Defendant-Appellee.
Roderick G. Dorman, Hennigan, Bennett & Dormann LLP, of Los Angeles,
California, argued for plaintiff/counterclaimant defendant-appellant. With him on the
brief were Lawrence M. Hadley, Bless S. Young, and Hazim H. Ansari.
Kelly C. Hunsaker, Fish & Richardson P.C., of Redwood City, California, argued
for defendant/counterclaimant-appellee. With him on the brief for Microsoft Corporation
were Juanita R. Brooks and William Chad Shear, of San Diego, California. Of counsel
was Robert B. Lytle, Microsoft Corporation, of Redmond, Washington.
Daniel T. Conrad, Jones Day, of Dallas Texas, argued for defendant-appellee.
With him on the brief for Dell Computer Corporation was Mark N. Reiter. Of counsel
was Amy E. Blackwelder.
Appealed from: United States District Court for the Central District of California
Judge Manuel L. Real

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NOTE: This disposition is nonprecedential.
United States Court of Appeals for the Federal Circuit
2006-1603
DATA ENCRYPTION CORPORATION,
Plaintiff/Counterclaim Defendant-
Appellant,
v.
MICROSOFT CORPORATION,
Defendant/Counterclaimant-
Appellee,
and
DELL COMPUTER CORPORATION,
Defendant-Appellee.
__________________________
DECIDED: September 6, 2007
__________________________
Before RADER, BRYSON, and PROST, Circuit Judges.
PROST, Circuit Judge.
Plaintiff-Appellant, Data Encryption Corporation (“Data”) appeals the decision of
the United States District Court for the Central District of California granting summary
judgment of noninfringement of U.S. Patent No. 5,584,023 (the “’023 patent”) in favor of
Defendants-Appellees, Microsoft Corporation (“Microsoft”) and Dell Computer

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Corporation (“Dell”). Data Encryption Corp. v. Microsoft Computer Corp., No. 05-CV-
05531 (C.D. Cal. Aug. 14, 2006). We affirm.
I. BACKGROUND
Data is the owner of the ’023 patent, entitled “Computer System Including a
Transparent and Secure File Transform Mechanism.” Generally speaking, the ’023
patent is directed to computer systems that encrypt and decrypt files. On July 29, 2005,
Data sued Microsoft and Dell, alleging that Microsoft’s Windows operating systems and
Dell computers using Windows operating systems infringed claims 5-12 of the ’023
patent.
The parties filed cross motions for summary judgment. On August 14, 2006, the
district court (1) granted Microsoft’s motion for summary judgment of noninfringement,
(2) granted Dell’s motion for summary judgment of noninfringement, and (3) denied
Data’s motion for partial summary judgment of infringement of claims 5, 6, and 7 by
Microsoft and Dell.
Data appeals. We have jurisdiction under 28 U.S.C. § 1295(a)(1).
II. DISCUSSION
A
On appeal, Data argues that the district court misconstrued the asserted claims
and that, therefore, the district court’s infringement analysis was incorrect. We review
the district court’s claim construction de novo. Cybor Corp. v. FAS Techs., Inc., 138
F.3d 1448, 1456 (Fed. Cir. 1998) (en banc). We also review de novo the district court’s
grant of summary judgment of noninfringement. O2 Micro Int’l Ltd. v. Monolithic Power
Sys., Inc., 467 F.3d 1355, 1369 (Fed. Cir. 2006).
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Of the asserted claims, claims 5 and 8 are independent. Claim 5 recites:1
5. A computer system including a file encryption mechanism, said system
comprising:
a) a file store providing for the storage of a file including one or
more blocks of data;
b) a memory store providing for the storage of blocks of data in first
and second logical data areas; and
c) a processor coupled to said memory store and said file store for
executing instructions implementing a computer operating
system as stored in said first logical data area and an application
program as stored in said second logical data area, said
processor providing for the controlled transfer of a predetermined
block of data between said file store and said data store means,
said processor including:
i) an encryption routine, defined by the execution of
instructions of said computer operating system, for
encrypting and decrypting said predetermined block of
data in said first logical data area separately from another
block of data;
ii) a request routine, defined by the execution of instructions
of said application program, for selecting said
predetermined block of data to be operated on by the
execution of instructions of said application program in
said second logical data area; and
iii) a system interface routine, defined by the execution of
instructions of said computer operating system and
responsive to said request routine, that controls the
transfer of said predetermined block of data between said
file store and said data store and between said first and
second logical data areas of said data store, said system
interface routine determining whether said predetermined
block of data is encrypted as stored by said file store, said
system interface routine selectively directing the transfer
of said predetermined block of data between said first and
second logical data areas through said encryption routine.
(Emphases added). The parties agreed before the district court that the term “first
logical data area” as recited in the claim refers to the kernel memory area and that the
term “second logical data area” refers to the user memory area.
1 On appeal, Data presents no separate argument regarding independent
claim 8. We therefore discuss only independent claim 5.
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In granting summary judgment of noninfringement, the district court held that
certain statements in the specification amounted to a disavowal of coverage of systems
that maintain data subject to encryption in an unencrypted state in the kernel memory
buffer pool, or cache. Data Encryption Corp. v. Microsoft Computer Corp., No. 05-CV-
05531, slip op. at 2 (C.D. Cal. Aug. 14, 2006) (order granting Microsoft’s motion for
summary judgment). The court further held that the phrase “system interface routine
selectively directing the transfer of said predetermined block of data between said first
and second logical data areas through said encryption routine” requires that “the
encryption routine in kernel memory transforms (i.e., encrypts or decrypts) the data in
user memory when it is transferred between kernel memory and user memory, not
when it is transferred between memory and the disk.” Id. In light of its interpretation,
the court concluded that there was no genuine dispute as to any material fact that
Microsoft Windows products did not infringe any of the asserted claims and,
accordingly, granted summary judgment to Microsoft and Dell. Id., slip op. at 2-3; Data
Encryption Corp. v. Microsoft Computer Corp., No. 05-CV-05531, slip op. at 2 (C.D. Cal.
Aug. 14, 2006) (order granting Dell’s motion for summary judgment).
B
At issue is the proper construction of the phrase “system interface routine
selectively directing the transfer of said predetermined block of data between said first
and second logical data areas through said encryption routine.” Data argues that the
district court incorrectly concluded that the inventor disavowed coverage of systems that
maintain data subject to encryption in an unencrypted state in the kernel memory buffer
pool.
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We agree with the district court that the specification reveals a disavowal of claim
scope. See Phillips v. AWH Corp., 415 F.3d 1303, 1316 (Fed. Cir. 2005) (en banc)
([T]he specification may reveal an intentional disclaimer, or disavowal, of claim scope by
the inventor. In that instance . . ., the inventor has dictated the correct claim scope, and
the inventor’s intention, as expressed in the specification, is regarded as dispositive.”).
The ’023 patent specification explains that, in accordance with the invention,
data pending either a read or write operation to disk 22 or other storage
medium persists only in an encrypted state. All data subject to encryption
by operation of the present invention is maintained in an encrypted state in
the buffer pool.2
’023 patent, col. 14, ll. 10-14 (emphasis added). This language is unambiguous. By
stating that “[a]ll data subject to encryption by operation of the present invention is
maintained in an encrypted state in the [kernel memory] buffer pool,” the inventor has
disavowed coverage of systems that maintain data subject to encryption in an
unencrypted state in the kernel memory buffer pool.
Data nevertheless asserts that the above-quoted language should not inform the
construction of claim 5—and should therefore not amount to a disavowal of claim
scope—because claim 5 makes no mention of how data is “maintained” in the kernel
memory buffer pool. While it is true that claim 5 makes no mention of how data is
maintained in the kernel memory buffer pool, it is also true that claim 5 specifies that the
system decrypts data when it is transferred from the kernel memory to the user
memory. Specifically, claim 5 requires the system to “selectively direct[] the transfer of
said predetermined block of data between said first and second logical data areas[, i.e.,
2 The buffer pool is located within the kernel memory area. See ’023
patent, col. 5, ll. 63-64 (“Within the kernel space, a buffer pool, or buffer cache, is
maintained by the operating system.”).
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2006-1603 6
between the kernel memory and the user memory,] through said encryption routine.”
Thus, the specification’s statement that “[a]ll data subject to encryption by operation of
the present invention is maintained in an encrypted state in the [kernel memory] buffer
pool” is clearly relevant to claim 5’s requirement that data be decrypted upon its transfer
from the kernel memory to the user memory.
In light of the inventor’s disavowal of claim scope, we affirm the district court’s
grant of summary judgment of noninfringement. Data does not dispute that, in normal
operation, Windows operating systems maintain data subject to encryption in an
unencrypted state in the kernel memory buffer pool, or cache.
Notwithstanding the disavowal, Data argues that there is a genuine issue of
material fact regarding infringement by operation of Windows operating systems in non-
default mode. We have carefully examined Data’s arguments in this regard and find
them to be unpersuasive. We similarly find unpersuasive Data’s contention that the
district court erroneously denied its motion for further discovery pursuant to Federal
Rule of Civil Procedure 56(f).
III. CONCLUSION
For the above reasons, we affirm the district court’s judgment of noninfringement.

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