JMAP extension for S/MIME signing and encryption
draft-ietf-jmap-smime-sender-extensions-00

Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Informational                            19 August 2021
Expires: 20 February 2022

            JMAP extension for S/MIME signing and encryption
               draft-ietf-jmap-smime-sender-extensions-00

Abstract

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

Status of This Memo

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   This Internet-Draft will expire on 20 February 2022.

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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 . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  JMAP capability registration for "smime-advanced" . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

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

   o 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
   specified arguments (the "original message").  This is done by
   encapsulating the original message either inside application/
   pkcs7-mime or multipart/signed container.  If multiple addresses are
   present in one of these header fields, or there is more than one

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   Sender/From header field, the server SHOULD reject the Email/set as
   invalid o 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).  [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: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.; otherwise, it MUST take the first
   address in the last Sender/From header field.(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",
                "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,

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              "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:

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

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   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>.

   [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

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   TW12 2NP
   United Kingdom

   Email: Alexey.Melnikov@isode.com

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