%% You should probably cite draft-ietf-keyprov-symmetrickeyformat instead of this I-D.
@techreport{turner-symmetrickeyformat-00,
    number =    {draft-turner-symmetrickeyformat-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-turner-symmetrickeyformat/00/},
    author =    {Sean Turner and Russ Housley},
    title =     {{Symmetric Key Package Content Type}},
    pagetotal = 9,
    year =      2007,
    month =     jul,
    day =       3,
    abstract =  {This document defines the symmetric key format content type. It is transport independent. The Cryptographic Message Syntax {[}RFC3852{]} can be used to digitally sign, digest, authenticate, or encrypt this content type.},
}