@misc{rfc5906,
    series =    {Request for Comments},
    number =    5906,
    howpublished =  {RFC 5906},
    publisher = {RFC Editor},
    doi =       {10.17487/RFC5906},
    url =       {https://www.rfc-editor.org/info/rfc5906},
    author =    {Professor David L. Mills and Brian Haberman},
    title =     {{Network Time Protocol Version 4: Autokey Specification}},
    pagetotal = 58,
    year =      2010,
    month =     jun,
    abstract =  {This memo describes the Autokey security model for authenticating servers to clients using the Network Time Protocol (NTP) and public key cryptography. Its design is based on the premise that IPsec schemes cannot be adopted intact, since that would preclude stateless servers and severely compromise timekeeping accuracy. In addition, Public Key Infrastructure (PKI) schemes presume authenticated time values are always available to enforce certificate lifetimes; however, cryptographically verified timestamps require interaction between the timekeeping and authentication functions. This memo includes the Autokey requirements analysis, design principles, and protocol specification. A detailed description of the protocol states, events, and transition functions is included. A prototype of the Autokey design based on this memo has been implemented, tested, and documented in the NTP version 4 (NTPv4) software distribution for the Unix, Windows, and Virtual Memory System (VMS) operating systems at http://www.ntp.org. This document is not an Internet Standards Track specification; it is published for informational purposes.},
}