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. 2Page: Previous 1 2 3 4 5 6 7 8 9 10 NextLast modified: November 3, 2007