%% You should probably cite draft-ietf-httpbis-message-signatures instead of this I-D.
@techreport{cavage-http-signatures-00,
    number =    {draft-cavage-http-signatures-00},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-cavage-http-signatures/00/},
    author =    {Mark Cavage and Manu Sporny},
    title =     {{HTTP Signatures}},
    pagetotal = 10,
    year =      2013,
    month =     may,
    day =       4,
    abstract =  {This document describes a way to add origin authentication, message integrity, and replay resistance to HTTP requests. It is intended to be used over the HTTPS protocol.},
}