@techreport{ietf-lamps-header-protection-25, number = {draft-ietf-lamps-header-protection-25}, type = {Internet-Draft}, institution = {Internet Engineering Task Force}, publisher = {Internet Engineering Task Force}, note = {Work in Progress}, url = {https://datatracker.ietf.org/doc/draft-ietf-lamps-header-protection/25/}, author = {Daniel Kahn Gillmor and Bernie Hoeneisen and Alexey Melnikov}, title = {{Header Protection for Cryptographically Protected E-mail}}, pagetotal = 269, year = 2025, month = jan, day = 6, abstract = {S/MIME version 3.1 introduced a mechanism to provide end-to-end cryptographic protection of e-mail message headers. However, few implementations generate messages using this mechanism, and several legacy implementations have revealed rendering or security issues when handling such a message. This document updates the S/MIME specification (RFC8551) to offer a different mechanism that provides the same cryptographic protections but with fewer downsides when handled by legacy clients. Furthermore, it offers more explicit usability, privacy, and security guidance for clients when generating or handling e-mail messages with cryptographic protection of message headers. The Header Protection scheme defined here is also applicable to messages with PGP/MIME cryptographic protections.}, }