Appeal No. 2000-1330
Application No. 08/972,835
high level of security against attackers. At the same time,
with knowledge of a secret distribution key, a government
agency is presented with a lower work factor.
Independent claim 1 is reproduced as follows:
1. A method for providing a cryptographic key for
cryptographically processing information, said method
comprising the steps of:
(a) generating a first key according to a key generator
scheme;
(b) reducing a key space of said first key in accordance
with a key space reduction function; and
(c) distributing said reduced key space over a larger key
space in accordance with a one-way key space distribution
function to provide said cryptographic key; wherein:
said cryptographic key has an associated first work
factor S for a person without knowledge of said key space
distribution function; and
said cryptographic key has an associated second work
factor W < S for a person with knowledge of said key space
distribution function.
The Examiner relies on the following references:
Elander et al. (Elander) 5,323,464 June 21,
1994
Applied Cryptography, Bruce Schneier, CIP of 1993 and
copyright of 1994.
Claims 1 through 6, 8 through 20 and 23 through 31 stand
rejected under 35 U.S.C. § 103 as unpatentable over Elander.
2
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