%% You should probably cite rfc8591 instead of this I-D. @techreport{campbell-sip-messaging-smime-02, number = {draft-campbell-sip-messaging-smime-02}, type = {Internet-Draft}, institution = {Internet Engineering Task Force}, publisher = {Internet Engineering Task Force}, note = {Work in Progress}, url = {https://datatracker.ietf.org/doc/draft-campbell-sip-messaging-smime/02/}, author = {Ben Campbell and Russ Housley}, title = {{Securing Session Initiation Protocol (SIP) based Messaging with S/MIME}}, pagetotal = 36, year = 2017, month = dec, day = 26, abstract = {Mobile messaging applications used with the Session Initiation Protocol (SIP) commonly use some combination of the SIP MESSAGE method and the Message Session Relay Protocol (MSRP). While these provide mechanisms for hop-by-hop security, neither natively provides end-to-end protection. This document offers guidance on how to provide end-to-end authentication, integrity protection, and confidentiality using the Secure/Multipurpose Internet Mail Extensions (S/MIME). It updates and provides clarifications for RFC 3261, RFC 3428, and RFC 4975.}, }