Network Working Group A. Melnikov
Internet-Draft Isode Ltd
Intended status: Informational July 12, 2021
Expires: January 13, 2022
JMAP extension for S/MIME signing and encryption
draft-melnikov-jmap-smime-advanced-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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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" . . . . . . . . 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
[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:
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/
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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.
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).
(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" ]]
Example 1:
5. IANA Considerations
5.1. JMAP capability registration for "smime"
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
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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
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Alexey Melnikov
Isode Ltd
14 Castle Mews
Hampton, Middlesex TW12 2NP
UK
EMail: Alexey.Melnikov@isode.com
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