Negotiated Finite Field Diffie-Hellman Ephemeral Parameters for Transport Layer Security (TLS) (RFC7919)
Original Publication Date: 2016-Aug-01
Included in the Prior Art Database: 2016-Aug-11
Internet Society Requests For Comment (RFCs)
Traditional TLS [RFC5246] offers a Diffie-Hellman Ephemeral (DHE) key exchange mode that provides forward secrecy for the connection. The client offers a cipher suite in the ClientHello that includes DHE, and the server offers the client group parameters generator g and modulus p. If the client does not consider the group strong enough (e.g., p is too small, p is not prime, or there are small subgroups that cannot be easily avoided) or if it is unable to process the group for other reasons, the client has no recourse but to terminate the connection.
Internet Engineering Task Force (IETF) D. Gillmor Request for Comments: 7919 ACLU Updates: 2246, 4346, 4492, 5246 August 2016 Category: Standards Track ISSN: 2070-1721
Negotiated Finite Field Diffie-Hellman Ephemeral Parameters for Transport Layer Security (TLS)
Traditional finite-field-based Diffie-Hellman (DH) key exchange during the Transport Layer Security (TLS) handshake suffers from a number of security, interoperability, and efficiency shortcomings. These shortcomings arise from lack of clarity about which DH group parameters TLS servers should offer and clients should accept. This document offers a solution to these shortcomings for compatible peers by using a section of the TLS "Supported Groups Registry" (renamed from "EC Named Curve Registry" by this document) to establish common finite field DH parameters with known structure and a mechanism for peers to negotiate support for these groups.
This document updates TLS versions 1.0 (RFC 2246), 1.1 (RFC 4346), and 1.2 (RFC 5246), as well as the TLS Elliptic Curve Cryptography (ECC) extensions (RFC 4492).
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7919.
Gillmor Standards Track [Page 1]
RFC 7919 Negotiated FFDHE for TLS August 2016
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.