%% You should probably cite draft-nygren-tls-client-puzzles-02 instead of this revision.
@techreport{nygren-tls-client-puzzles-01,
    number =    {draft-nygren-tls-client-puzzles-01},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-nygren-tls-client-puzzles/01/},
    author =    {Erik Nygren and Samuel Erb and Alex Biryukov and Dmitry Khovratovich},
    title =     {{TLS Client Puzzles Extension}},
    pagetotal = 13,
    year =      2016,
    month =     jun,
    day =       28,
    abstract =  {Client puzzles allow a TLS server to defend itself against asymmetric DDoS attacks. In particular, it allows a server to request clients perform a selected amount of computation prior to the server performing expensive cryptographic operations. This allows servers to employ a layered defense that represents an improvement over pure rate-limiting strategies. Client puzzles are implemented as an extension to TLS 1.3 {[}I-D.ietf-tls-tls13{]} wherein a server can issue a HelloRetryRequest containing the puzzle as an extension. The client must then resend its ClientHello with the puzzle results in the extension.},
}