PEM file format for ESNI
draft-farrell-tls-pemesni-00

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TLS                                                           S. Farrell
Internet-Draft                                    Trinity College Dublin
Intended status: Experimental                           October 28, 2019
Expires: April 30, 2020

                        PEM file format for ESNI
                      draft-farrell-tls-pemesni-00

Abstract

   Encrypted SNI key pairs need to be configured into TLS servers, some
   of which can be built with different TLS libraries, so there is a
   benefit and little cost in documenting a file format to use for
   these, similar to how RFC7468 defines other PEM file formats.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on April 30, 2020.

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   Copyright (c) 2019 IETF Trust and the persons identified as the
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  ESNIKeys file . . . . . . . . . . . . . . . . . . . . . . . .   2
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   Encrypted Server Name Indication (ESNI) [I-D.ietf-tls-esni] for
   TLS1.3 [RFC8446] defines a confidentiality mechanism for server names
   in TLS.  That requires publication of an ESNIKeys data structure in
   the DNS.  An ESNIKeys structure contains the public component of a
   key pair that will typically be periodically (re-)generated by some
   key manager for a TLS server.  TLS servers then need to be configured
   to use these key pairs, and given that various TLS servers can be
   built with different TLS libraries, there is a benefit in having a
   standard format for ESNI key pairs, just as was done with [RFC7468].

   [[This idea could: a) wither on the vine, b) be published as it's own
   RFC, or c) end up as a PR for [I-D.ietf-tls-esni].  There is no
   absolute need for this to be in the RFC that defines ESNI, so (b)
   seems feasible if there's enough interest, hence this draft.  The
   source for this is in https://github.com/sftcd/pemesni/ PRs are
   welcome there too.]]

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  ESNIKeys file

   The public and private keys MUST both be PEM encoded.  The file
   contains the catenation of the PEM encoding of the private key
   followed by the PEM encoding of the public key.  The private key MUST
   be encoded as a PKCS#8 PrivateKey.  The public key MUST be the base64
   encoded form of the binary ESNIKeys value that is published in the
   DNS.  The string "ESNIKEY" MUST be used in the PEM file delimiter for
   the public key.

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   There MUST only be one key pair in each file even if a server
   publishes multiple public keys in one ESNIKeys structure.

   Figure 1 shows an example ESNI PEM File

-----BEGIN PRIVATE KEY-----
MC4CAQAwBQYDK2VuBCIEIEDyEDpfvLoFYQi4rNjAxAz7F/Dqydv5IFmcPpIyGNd8
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