NOTE: This disposition is nonprecedential. 

United States Court of Appeals for the Federal Circuit 

2006-1603 

DATA ENCRYPTION CORPORATION, 

Plaintiff/Counterclaim DefendantAppellant, 

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 
NOTE: This disposition is nonprecedential.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 
Corporation (“Dell”). Data Encryption Corp. v. Microsoft Computer Corp., No. 05-CV05531 (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). 

2006-1603 2
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. 

2006-1603 3
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-CV05531, 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. 

2006-1603 4
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.”). 

2006-1603 5
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 nondefault 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.