%% You should probably cite draft-stenn-ntp-mac-last-ef-04 instead of this revision. @techreport{stenn-ntp-mac-last-ef-01, number = {draft-stenn-ntp-mac-last-ef-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-stenn-ntp-mac-last-ef/01/}, author = {Harlan Stenn and Danny Mayer}, title = {{Network Time Protocol MAC/Last Extension Fields}}, pagetotal = 7, year = 2017, month = nov, day = 30, abstract = {NTPv4 is defined by RFC 5905 {[}RFC5905{]}, and it and earlier versions of the NTP Protocol have supported symmetric private key Message Authentication Code (MAC) authentication. MACs were first described in Appendix C of RFC 1305 {[}RFC1305{]} and are further described in RFC 5905 {[}RFC5905{]}. As the number of Extension Fields grows there is an increasing chance of a parsing ambiguity when deciding if the "next" set of data is an Extension Field or a legacy MAC. This proposal defines two new Extension Fields to avoid this ambiguity. One, LAST- EF, is used to signifiy that it is the last Extension Field in the packet. If the LAST-EF is present, any subsequent data MUST be considered to be a legacy MAC. The other, MAC-EF, allows one or more MACs to be encapsulated in an Extension Field. If all parties in an association support MAC-EF, the use of a legacy MAC may be avoided.}, }