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Security '01 Abstract

Using Client Puzzles to Protect TLS

Drew Dean, Xerox PARC and Adam Stubblefield, Rice University


Client puzzles are commonly proposed as a solution to denial-of-service attacks. However, very few implementations of the idea actually exist, and there are a number of subtle details in the implementation. In this paper, we describe our implementation of a simple and backwards compatible client puzzle extension to TLS. We also present measurements of CPU load and latency when our modified library is used to protect a secure webserver. These measurements show that client puzzles are a viable method for protecting SSL servers from SSL based denial-of-service attacks.
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Last changed: 30 Apr 2002 ml
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