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Secure Negotiation of Incompatible Protocols in TLS

Document Type Expired Internet-Draft (tls WG)
Expired & archived
Author Martin Thomson
Last updated 2023-01-01 (Latest revision 2022-06-30)
Replaces draft-thomson-tls-snip
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Additional resources Mailing list discussion
Stream WG state WG Document
Document shepherd (None)
IESG IESG state Expired
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft is available in these formats:


An extension is defined for TLS that allows a client and server to detect an attempt to force the use of less-preferred application protocol even where protocol options are incompatible. This supplements application-layer protocol negotiation (ALPN), which allows choices between compatible protocols to be authenticated.


Martin Thomson

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)