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Computational Puzzles for SPAM Reduction in SIP

Document Type Expired Internet-Draft (individual)
Expired & archived
Author Cullen Fluffy Jennings
Last updated 2007-07-09
RFC stream (None)
Intended RFC status (None)
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


One of the techniques used in SPAM prevention and various solutions for denial of service attacks is to force the SIP client requesting a service to perform a calculation that limits the rate and increases the cost of the request. This draft defines a way to allow a UAS to ask the UAC to compute a computationally expensive hash based function and present the result to the UAS. Although the computation is expensive for the UAC to compute, it is cheap for the UAS to verify. The solution also allows for proxies to compute and check the puzzle on behalf of the UAC or UAS. This draft currently outlines enough information to evaluate and consider this approach or even run experiments. It would need finalization around the forking topics discussed in the open issues before it would be implementable in production system.


Cullen Fluffy Jennings

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)