Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Informational                           8 November 2021
Expires: 12 May 2022


            JMAP extension for S/MIME signing and encryption
               draft-ietf-jmap-smime-sender-extensions-01

Abstract

   This document specifies an extension to JMAP for sending S/MIME
   signed and S/MIME encrypted messages.

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 12 May 2022.

Copyright Notice

   Copyright (c) 2021 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
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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Simplified BSD License.







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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   2
   3.  Addition to the capabilities object . . . . . . . . . . . . .   2
   4.  Extension to Email/set for S/MIME signing and/or
           encryption  . . . . . . . . . . . . . . . . . . . . . . .   2
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  JMAP capability registration for "smime-advanced" . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   [RFC8621] is a JSON based application protocol for synchronising
   email data between a client and a server.

   This document describes an extension to JMAP for sending S/MIME
   signed and encrypted messages .  It allows JMAP server to sign/
   encrypt messages on user's behalf.

2.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  Addition to the capabilities object

   The capabilities object is returned as part of the standard JMAP
   Session object; see the JMAP spec.  Servers supporting _this_
   specification MUST add a property called "urn:ietf:params:jmap:smime-
   advanced" to the capabilities object.

   The value of this property is an empty object in both the JMAP
   session _capabilities_ property and an account's
   _accountCapabilities_ property.

4.  Extension to Email/set for S/MIME signing and/or encryption

   [RFC8621] defines Email/set method for creating new email messages.
   This document defines the following additional request arguments that
   can be used to create S/MIME signed and/or encrypted messages:

   *  smimeSign: "Boolean" (default: false).  If included and has the
      value "true", this requests the JMAP server to create an S/MIME
      signed message from the message constructed according to other



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      specified arguments (the "original message").  This is done by
      encapsulating the original message either inside application/
      pkcs7-mime or multipart/signed container.  The signature's private
      key/certificate is associated with the email address in the Sender
      header field, if present; otherwise, it is associated with the
      email address in the From header field, if present.

      If multiple addresses are present in one of these header fields,
      or there is more than one Sender/From header field, the server
      SHOULD reject the Email/set as invalid; otherwise, it MUST take
      the first address in the last Sender/From header field.

   *  smimeEncrypt: "Boolean" (default: false).  If included and has the
      value "true", this requests the JMAP server to create an S/MIME
      encrypted message from the constructed message.  This is done by
      encapsulating the message inside application/pkcs7-mime media
      type.  The message MUST be encrypted to the sender and all To/Cc/
      Bcc recipients.  This extension assumes that there is some kind of
      per user or organizational addressbook, that can be used to lookup
      public keys of recipients.  If lookup of a particular public key
      fails, or results in an expired or revoked certificate, the Email/
      set operation MUST fail.

   If both "smimeSign" and "smimeEncrypt" are set to true, the message
   is first signed and then the signed version is encrypted (in that
   order).

   (Note that this extension doesn't allow management of private keys/
   certificates.  How private keys are managed or configured for a
   particular user is out of scope for this document.)

   [[How to control header protection?]]



        [[ "Email/set", {
          "accountId": "ue150411c",
          "create": {
            "k192": {
              "mailboxIds": {
                "2ea1ca41b38e": true
              },
              "keywords": {
                "$seen": true,
                "$draft": true
              },
              "from": [{
                "name": "Joe Bloggs",



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                "email": "joe@example.com"
              }],
              "subject": "World domination",
              "receivedAt": "2021-07-07T01:03:11Z",
              "sentAt": "2021-07-10T11:03:11+10:00",
              "smimeSign": true,
              "smimeEncrypt": true,
              "bodyStructure": {
                "type": "text/plain",
                "partId": "bd48",
                "header:Content-Language": "en"
              },
              "bodyValues": {
                "bd48": {
                  "value": "I have the most brilliant plan.  Let me tell
                    you all about it.",
                  "isTruncated": false
                }
              }
            }
          }
        }, "0" ]]

  This will result in the following response:

        [[ "Email/set", {
          "accountId": "ue150411c",
          "oldState": "780823",
          "newState": "780839",
          "created": {
            "k192": {
              "id": "Mf40b5f831efa7233b9eb1c7f",
              "blobId": "Gf40b5f831efa7233b9eb1c7f8f97d84eeeee64f7",
              "threadId": "Td957e72e89f516dc",
              "size": 5096
            }
          },
          ...
        }, "0" ]]

                           Figure 1: Example 1:










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5.  IANA Considerations

5.1.  JMAP capability registration for "smime-advanced"

   IANA is requested to register the "smime" JMAP Capability as follows:

   Capability Name: "urn:ietf:params:jmap:smime-advanced"

   Specification document: this document

   Intended use: common

   Change Controller: IETF

   Security and privacy considerations: this document, Section 6

6.  Security Considerations

   This JMAP extension assumes trust between the user and the JMAP
   server for purposes of signing and encrypting messages on user's
   behalf.

   This JMAP extension also relies on access to user's (or
   organization's) addressbook which contain up-to-date certificates for
   recipients.

   This JMAP extension doesn't support management of user's private keys
   and corresponding certificates.

7.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8550]  Schaad, J., Ramsdell, B., and S. Turner, "Secure/
              Multipurpose Internet Mail Extensions (S/MIME) Version 4.0
              Certificate Handling", RFC 8550, DOI 10.17487/RFC8550,
              April 2019, <https://www.rfc-editor.org/info/rfc8550>.

   [RFC8551]  Schaad, J., Ramsdell, B., and S. Turner, "Secure/
              Multipurpose Internet Mail Extensions (S/MIME) Version 4.0
              Message Specification", RFC 8551, DOI 10.17487/RFC8551,
              April 2019, <https://www.rfc-editor.org/info/rfc8551>.






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   [RFC8620]  Jenkins, N. and C. Newman, "The JSON Meta Application
              Protocol (JMAP)", RFC 8620, DOI 10.17487/RFC8620, July
              2019, <https://www.rfc-editor.org/info/rfc8620>.

   [RFC8621]  Jenkins, N. and C. Newman, "The JSON Meta Application
              Protocol (JMAP) for Mail", RFC 8621, DOI 10.17487/RFC8621,
              August 2019, <https://www.rfc-editor.org/info/rfc8621>.

Author's Address

   Alexey Melnikov
   Isode Ltd
   14 Castle Mews
   Hampton
   TW12 2NP
   United Kingdom

   Email: Alexey.Melnikov@isode.com

































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