Title: RSA Security's Statement about IPR claimed in 
       draft-ietf-ipsec-properties-00 and
       draft-jennings-sip-hashcash-00
Received: 30 August 2004 
From: Linn, John <jlinn@rsasecurity.com>

RSA Security Inc. has submitted a patent application (US 
Serial No. 09/496,824) concerning client puzzles, a technique 
initially described in Juels and Brainard, "Client Puzzles: A 
Cryptographic Countermeasure against Connection Depletion
Attacks", ISOC NDSS, 1999. As of 2001, discussions within the 
IPsec WG had cited this technique and had considered incorporation 
of methods with similar properties. Related concepts were referenced 
in 2001 in draft-ietf-ipsec-properties-00.txt (relative to which 
an IPR disclosure was submitted on 3 August 2001), and more recently 
in draft-jennings-sip-hashcash-00.txt. If use of client puzzles is 
incorporated into a future Internet standard, and if the currently active
application leads to an issued patent, RSA Security Inc. is willing to 
grant licenses to such patent under reasonable and non-discriminatory 
terms for purposes of implementing that Internet standard. 

Correspondence concerning licensing for this technology should be 
addressed to: 

RSA Security Inc., 
174 Middlesex Turnpike, 
Bedford, MA 01730, USA, 
Attn: General Counsel.