Appeal No. 2006-3120
Application No. 09/944,695
Appellant argues that the examiner failed to establish a prima facie case
of obviousness for three main reasons. First, the examiner’s motivation to
combine the references – namely “to prevent unauthorized printing and spoofing”
– is a mere desired result that, unlike the claimed invention, cannot be achieved
with the cited references [brief, page 6]. Appellant emphasizes that unauthorized
printing is possible in the prior art arrangement since Mazzagatte’s system only
encrypts at the printer, and a spoofer in DeBry’s system could intercept
documents if they are able to fake the system printer’s certification by encrypting
the symmetric key using the spoofer’s public key [brief, pages 6 and 7]. In the
claimed invention, however, printing is secure because the user controls the
private key. In short, no decryption is possible until the user arrives at the printer
and enters their private key [brief, pages 7 and 8; reply brief, page 5]. Second,
appellant contends that there is no reasonable expectation that the claimed
invention could be derived from the teachings of the prior art – even by an
“expert” [brief, page 8].
Third, appellant argues that, even if the references are combined, the prior
art does not disclose all claimed limitations, namely (1) encrypting the document
with a public key; (2) accepting a private key at the printer; and (3) decrypting the
document with the private key [brief, page 8]. In this regard, appellant notes that
Mazzagatte does not describe the transmission of the document using a
public/private key pair. Also, DeBry does not encrypt the document using a
public key, but rather encrypts a symmetric key using a public key. Appellant
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