@misc{rfc1421,
    series =    {Request for Comments},
    number =    1421,
    howpublished =  {RFC 1421},
    publisher = {RFC Editor},
    doi =       {10.17487/RFC1421},
    url =       {https://www.rfc-editor.org/info/rfc1421},
    author =    {John Linn},
    title =     {{Privacy Enhancement for Internet Electronic Mail: Part I: Message Encryption and Authentication Procedures}},
    pagetotal = 42,
    year =      1993,
    month =     feb,
    abstract =  {This document defines message encryption and authentication procedures, in order to provide privacy-enhanced mail (PEM) services for electronic mail transfer in the Internet. {[}STANDARDS-TRACK{]}},
}