Automatic Certificate Management Environment (ACME) Onion v3 Identifier Validation Extension
draft-shoemaker-acme-onion-00

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ACME Working Group                                        R.B. Shoemaker
Internet-Draft                                                      ISRG
Intended status: Standards Track                           29 April 2020
Expires: 31 October 2020

Automatic Certificate Management Environment (ACME) Onion v3 Identifier
                          Validation Extension
                     draft-shoemaker-acme-onion-00

Abstract

   This document specifies identifiers and challenges required to enable
   the Automatic Certificate Management Environment (ACME) to issue
   certificates for Onion Addresses as specified in Tor Rendezvous
   Specification - Version 3.

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 31 October 2020.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Onion Address Identifier  . . . . . . . . . . . . . . . . . .   2
   4.  Onion CSR Challenge . . . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Identifier Types  . . . . . . . . . . . . . . . . . . . .   4
     5.2.  Challenge Types . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   9.  Informative References  . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   Currently the Automatic Certificate Management Environment (ACME)
   [RFC8555] only specifies how DNS identifiers and IP address
   identifiers [RFC8738] may be validated for inclusion in x.509
   certificates [RFC5280].  This document extends the protocol to
   include a validation mechanism for Tor version 3 Onion Addresses
   [TOR-REND-V3].

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.  Onion Address Identifier

   Version 3 Onion address identifier objects MUST use the type "onion-
   v3".  The value field of the identifier MUST contain the textual
   encoding of the address as defined as onion_address in [TOR-REND-V3]
   section 6.  ACME servers MUST verify that the value field contains a
   properly encoded address by checking that it contains only two
   labels, that first label contains a valid checksum, and that the last
   byte of the first label is \x03.  [TODO: this could probably be
   specified better?]

   An identifier for the version 3 Onion address address for the
   following Ed25519 public key would be formatted like so:

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   -----BEGIN PUBLIC KEY-----
   MCowBQYDK2VwAyEAAJhLnbvXNWu8WXre3Y0HU+1FErU13zcbO7pEqkI38+Q=
   -----END PUBLIC KEY-----

   {"type": "onion-v3", "value": "acmexhn3242wxpczplpn3dihkpwukevvgxptogz3xjckuqrx6pscepad.onion"}

4.  Onion CSR Challenge

   This document specifies a single new challenge type that can be used
   for validation of onion-v3 identifiers.  This challenge demonstrates