draft-ietf-calsify-rfc2447bis-06.txt   draft-ietf-calsify-rfc2447bis-07.txt 
INTERNET-DRAFT A. Melnikov INTERNET-DRAFT A. Melnikov
Document: draft-ietf-calsify-rfc2447bis-06.txt Editor Document: draft-ietf-calsify-rfc2447bis-07.txt Editor
Intended status: Standard Track September 6, 2009 Intended status: Standard Track October 9, 2009
Expires: March 2010 Expires: April 2010
iCalendar Message-Based Interoperability Protocol iCalendar Message-Based Interoperability Protocol
(iMIP) (iMIP)
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. This document may contain material provisions of BCP 78 and BCP 79. This document may contain material
from IETF Documents or IETF Contributions published or made publicly from IETF Documents or IETF Contributions published or made publicly
available before November 10, 2008. The person(s) controlling the available before November 10, 2008. The person(s) controlling the
skipping to change at page 2, line 5 skipping to change at page 2, line 5
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
A revised version of this draft document will be submitted to the RFC A revised version of this draft document will be submitted to the RFC
editor as a Draft Standard for the Internet Community. Discussion editor as a Draft Standard for the Internet Community. Discussion
and suggestions for improvement are requested, and should be sent to and suggestions for improvement are requested, and should be sent to
the CALSIFY Mailing list <ietf-calsify@osafoundation.org>. the CALSIFY Mailing list <ietf-calsify@osafoundation.org>.
Distribution of this document is unlimited. Distribution of this document is unlimited.
Copyright Notice Copyright Notice
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info). publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. and restrictions with respect to this document.
Abstract Abstract
This document, iCalendar Message-Based Interoperability Protocol This document, iCalendar Message-Based Interoperability Protocol
(iMIP), specifies a binding from the iCalendar Transport-independent (iMIP), specifies a binding from the iCalendar Transport-independent
Interoperability Protocol (iTIP) to Internet email-based transports. Interoperability Protocol (iTIP) to Internet email-based transports.
Calendaring entries defined by the iCalendar Object Model (iCAL) are Calendaring entries defined by the iCalendar Object Model (iCAL) are
composed using constructs from RFC 5322, RFC 2045, RFC 2046, RFC 2047 wrapped using constructs from RFC 5322, RFC 2045, RFC 2046, RFC 2047
and RFC 2049. and RFC 2049, and then transported over SMTP.
This document is a product of Calendaring and Scheduling Standards This document is a product of the Calendaring and Scheduling
Simplification (calsify) working group. More information about the Standards Simplification (calsify) working group. More information
IETF CALSIFY working group activities can be found on the IETF web about the IETF CALSIFY working group activities can be found on the
site at <http://www.ietf.org/html.charters/calsify-charter.html>. IETF web site at <http://www.ietf.org/html.charters/calsify-
charter.html>.
The issue tracker for the Calsify WG is located at: The issue tracker for the Calsify WG is located at:
<http://www.ofcourseimright.com/cgi-bin/roundup/calsify> <http://www.ofcourseimright.com/cgi-bin/roundup/calsify>
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
Table of Contents Table of Contents
1 INTRODUCTION........................................................2 1 INTRODUCTION........................................................2
1.1 RELATED MEMOS ...................................................2 1.1 RELATED MEMOS ...................................................2
1.2 FORMATTING CONVENTIONS ..........................................3 1.2 FORMATTING CONVENTIONS ..........................................3
1.3 TERMINOLOGY .....................................................4 1.3 TERMINOLOGY .....................................................4
2 MIME MESSAGE FORMAT BINDING.........................................4 2 MIME MESSAGE FORMAT BINDING.........................................4
2.1 MIME MEDIA TYPE .................................................4 2.1 MIME MEDIA TYPE .................................................4
2.2 SECURITY ........................................................4 2.2 SECURITY ........................................................4
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Implementers will need to be familiar with several other memos that, Implementers will need to be familiar with several other memos that,
along with this memo, form a framework for Internet calendaring and along with this memo, form a framework for Internet calendaring and
scheduling standards. scheduling standards.
This document, [iMIP], specifies an Internet email binding for iTIP. This document, [iMIP], specifies an Internet email binding for iTIP.
[iCAL] - specifies a core specification of objects, data types, [iCAL] - specifies a core specification of objects, data types,
properties and property parameters; properties and property parameters;
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
[iTIP] - specifies an interoperability protocol for scheduling [iTIP] - specifies an interoperability protocol for scheduling
between different implementations; between different implementations;
This memo does not attempt to repeat the specification of concepts or This memo does not attempt to repeat the specification of concepts or
definitions from these other memos. Where possible, references are definitions from these other memos. Where possible, references are
made to the memo that provides for the specification of these made to the memo that provides for the specification of these
concepts or definitions. concepts or definitions.
1.2 Formatting Conventions 1.2 Formatting Conventions
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Properties defined by [iCAL] are referred to with capitalized, Properties defined by [iCAL] are referred to with capitalized,
quoted-strings of text, followed by the word "property". For example, quoted-strings of text, followed by the word "property". For example,
"ATTENDEE" property refers to the iCalendar property used to convey "ATTENDEE" property refers to the iCalendar property used to convey
the calendar address of a calendar user. the calendar address of a calendar user.
Property parameters defined by [iCAL] are referred to with lower Property parameters defined by [iCAL] are referred to with lower
case, quoted-strings of text, followed by the word "parameter". For case, quoted-strings of text, followed by the word "parameter". For
example, "value" parameter refers to the iCalendar property parameter example, "value" parameter refers to the iCalendar property parameter
used to override the default data type for a property value. used to override the default data type for a property value.
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
1.3 Terminology 1.3 Terminology
The email terms used in this memo are defined in [RFC-5322] and The email terms used in this memo are defined in [RFC-5322] and
[RFC-2045]. The calendaring and scheduling terms used in this memo [RFC-2045]. The calendaring and scheduling terms used in this memo
are defined in [iCAL] and [iTIP]. are defined in [iCAL] and [iTIP].
2 MIME Message Format Binding 2 MIME Message Format Binding
This section defines the message binding to the MIME electronic mail This section defines the message binding to the MIME electronic mail
transport. transport.
The sections below refer to the "originator" and the "respondent" of The sections below refer to the "originator" and the "respondent" of
an iMIP message. Typically, the originator is the "Organizer" of an an iMIP message. Typically, the originator is the "Organizer" of an
event. The respondent is an "Attendee" of the event. event and the respondent is an "Attendee" of the event.
The [RFC-5322] "Reply-To" header typically contains the email address The [RFC-5322] "Reply-To" header typically contains the email address
of the originator or respondent of an event. However, this cannot be of the originator or respondent of an event. However, this cannot be
guaranteed as Mail User Agents (MUA) are not required to enforce iMIP guaranteed as Mail User Agents (MUA) are not required to enforce iMIP
semantics. semantics.
2.1 MIME Media Type 2.1 MIME Media Type
A MIME entity containing content information formatted according to A MIME entity containing content information formatted according to
this document will be referenced as a "text/calendar" content type. this document will be referenced as a "text/calendar" content type.
It is assumed that this content type will be transported through a It is assumed that this content type will be transported through a
MIME electronic mail transport. MIME electronic mail transport.
2.2 Security 2.2 Security
This section addresses several aspects of security including This section addresses several aspects of security including
Authentication, Authorization and Confidentiality. Authentication and authentication, authorization and confidentiality. Authentication and
confidentiality can be achieved using [RFC-1847] that specifies the confidentiality can be achieved using [RFC-1847] that specifies the
Security Multiparts for MIME. This framework defines new content Security Multiparts for MIME. This framework defines new content
types and subtypes of multipart: signed and encrypted. Each contains types and subtypes of multipart: signed and encrypted. Each contains
two body parts: one for the protected data and another for the two body parts: one for the protected data and another for the
control information necessary to remove the protection. control information necessary to remove the protection.
2.2.1 Authorization 2.2.1 Authorization
In [iTIP] messages, only the "Organizer" is authorized to modify or In [iTIP] messages, only the "Organizer" is authorized to modify or
cancel calendar entries they organize. That is, spoof@xyz.example.net cancel calendar entries she organizes. That is, spoof@xyz.example.net
is not allowed to modify or cancel a meeting that was organized by is not allowed to modify or cancel a meeting that was organized by
a@example.com. Furthermore, only the respondent has the authorization a@example.com. Furthermore, only the respondent has the authorization
to indicate their status to the "Organizer". That is, the "Organizer" to indicate their status to the "Organizer". That is, the "Organizer"
must ignore an [iTIP] message from spoof@xyz.example.net that must ignore an [iTIP] message from spoof@xyz.example.net that
declines a meeting invitation for b@example.com. declines a meeting invitation for b@example.com.
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
Implementations of iMIP SHOULD verify the authenticity of the creator Implementations of iMIP SHOULD verify the authenticity of the creator
of an iCalendar object before taking any action. The methods for of an iCalendar object before taking any action. The methods for
doing this are presented later in this document. doing this are presented later in this document.
[RFC-1847] Message flow in iTIP supports someone working on behalf of [RFC-1847] Message flow in iTIP supports someone working on behalf of
a "Calendar User" through use of the "sent-by" parameter that is a "Calendar User" through use of the "sent-by" parameter that is
associated with the "ATTENDEE" and "ORGANIZER" properties. However, associated with the "ATTENDEE" and "ORGANIZER" properties. However,
there is no mechanism to verify whether or not a "Calendar User" has there is no mechanism to verify whether or not a "Calendar User" has
authorized someone to work on their behalf. It is left to authorized someone to work on their behalf. It is left to
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"Attendee" cannot be reliably inferred by the [RFC-5322] "Sender" or "Attendee" cannot be reliably inferred by the [RFC-5322] "Sender" or
"Reply-to" values of an iMIP message. The relevant address MUST be "Reply-to" values of an iMIP message. The relevant address MUST be
ascertained by opening the "text/calendar" MIME body part and ascertained by opening the "text/calendar" MIME body part and
examining the "ATTENDEE" and "ORGANIZER" properties. examining the "ATTENDEE" and "ORGANIZER" properties.
2.4 Content Type 2.4 Content Type
A MIME body part containing content information that conforms to this A MIME body part containing content information that conforms to this
document MUST have an [RFC-2045] "Content-Type" value of document MUST have an [RFC-2045] "Content-Type" value of
"text/calendar". The [RFC-2045] "Content-Type" header field MUST also "text/calendar". The [RFC-2045] "Content-Type" header field MUST also
include the type parameter "method". The value MUST be the same as include the type parameter "method". The value MUST be the same
the value of the "METHOD" calendar property within the iCalendar (ignoring case) as the value of the "METHOD" calendar property within
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
object. the iCalendar object.
Note 1: A MIME message containing multiple iCalendar objects with Note 1: A MIME message containing multiple iCalendar objects with
different method values must be further encapsulated with a different method values must be further encapsulated with a
"multipart/mixed" MIME entity. This will allow each of the iCalendar "multipart/mixed" MIME entity. This will allow each of the iCalendar
objects to be encapsulated within their own "text/calendar" MIME objects to be encapsulated within their own "text/calendar" MIME
entity. entity.
Note 2: A MIME body part of "text/calendar" "Content-Type" that lacks Note 2: A MIME body part of "text/calendar" "Content-Type" that lacks
the "method" parameter is not considered to be an iMIP body part and the "method" parameter is not considered to be an iMIP body part and
thus is not subject to the requirements specified in this document. thus is not subject to the requirements specified in this document.
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type to be included in a MIME message with other content information type to be included in a MIME message with other content information
(i.e., "multipart/mixed") or included in a MIME message with a clear- (i.e., "multipart/mixed") or included in a MIME message with a clear-
text, human-readable form of the scheduling message (i.e., text, human-readable form of the scheduling message (i.e.,
"multipart/alternative"). "multipart/alternative").
In order to permit the information in the scheduling message to be In order to permit the information in the scheduling message to be
understood by MIME user agents (UA) that do not support the understood by MIME user agents (UA) that do not support the
"text/calendar" content type, scheduling messages SHOULD be sent with "text/calendar" content type, scheduling messages SHOULD be sent with
an alternative, human-readable form of the information. an alternative, human-readable form of the information.
Note that "multiple/alternative" MUST NOT be used to represent two Note that "multipart/alternative" MUST NOT be used to represent two
slightly different iCalendar objects, for example two VEVENT with slightly different iCalendar objects, for example two VEVENT with
alternative starting times. alternative starting times.
CUA can use language and other parameters to pick a "text/calendar" CUAs can use language <<add ref>> and other parameters to pick a
part if a "multipart/alternative" MIME message contains more than one "text/calendar" part if a "multipart/alternative" MIME message
"text/calendar" part. contains more than one "text/calendar" part.
Any receiving UA compliant with this specification MUST be able to Any receiving UA compliant with this specification MUST be able to
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
process "text/calendar" body parts enclosed within "multipart/*". process "text/calendar" body parts enclosed within "multipart/*".
Note that a "multipart/mixed" MIME message can include multiple Note that a "multipart/mixed" MIME message can include multiple
"text/calendar" components. The receiving UA MUST be able to process "text/calendar" components. The receiving UA MUST be able to process
all of them. all of them.
2.5 Content-Transfer-Encoding 2.5 Content-Transfer-Encoding
Unless iMIP message is transported over 8-bit clean transport (such Unless iMIP message is transported over 8-bit clean transport (such
as SMTP [8BITMIME]), a transfer encoding such as quoted-printable or as SMTP [8BITMIME]), a transfer encoding such as quoted-printable or
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Message-ID: <4821E731.5040506@laptop1.example.com> Message-ID: <4821E731.5040506@laptop1.example.com>
Content-Type: text/calendar; method=REQUEST; charset=UTF-8 Content-Type: text/calendar; method=REQUEST; charset=UTF-8
Content-Transfer-Encoding: quoted-printable Content-Transfer-Encoding: quoted-printable
BEGIN:VCALENDAR BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST METHOD:REQUEST
VERSION:2.0 VERSION:2.0
BEGIN:VEVENT BEGIN:VEVENT
ORGANIZER:mailto:user1@example.com ORGANIZER:mailto:user1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:user1@example.com ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:mailto:user1@example.com
ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:user2@example.com ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:user2@example.com
DTSTAMP:20080507T170000Z DTSTAMP:20080507T170000Z
DTSTART:20080701T160000Z DTSTART:20080701T160000Z
DTEND:20080701T163000Z DTEND:20080701T163000Z
SUMMARY:Phone call to discuss your last visit SUMMARY:Phone call to discuss your last visit
DESCRIPTION:=D1=82=D1=8B =D0=BA=D0=B0=D0=BA - =D0=B4=D0=BE=D0= DESCRIPTION:=D1=82=D1=8B =D0=BA=D0=B0=D0=BA - =D0=B4=D0=BE=D0=
=B2=D0=BE=D0=BB=D0=B5=D0=BD =D0=BF=D0=BE=D0=B5=D0=B7=D0=B4=D0=BA=D0=BE=D0= =B2=D0=BE=D0=BB=D0=B5=D0=BD =D0=BF=D0=BE=D0=B5=D0=B7=D0=B4=D0=BA=D0=BE=D0=
=B9? =B9?
UID:calsvr.example.com-8739701987387998 UID:calsvr.example.com-8739701987387998
SEQUENCE:0 SEQUENCE:0
STATUS:TENTATIVE STATUS:TENTATIVE
END:VEVENT END:VEVENT
END:VCALENDAR END:VCALENDAR
2.6 Content-Disposition 2.6 Content-Disposition
Implementations MAY include a "Content-Disposition" header field to Implementations MAY include a "Content-Disposition" header field to
define a file name for an iCalendar object. However, the handling of define a file name for an iCalendar object. However, the handling of
a MIME part MUST be based on its [RFC-2045] "Content-Type" and not on a MIME part MUST be based on its [RFC-2045] "Content-Type" and not on
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
the extension specified in the "Content-Disposition", as different the extension specified in the "Content-Disposition", as different
email malware is known to trick User Agents into misinterpreting email malware is known to trick User Agents into misinterpreting
content of messages by specifying a file extension in the Content- content of messages by specifying a file extension in the Content-
Disposition header field that doesn't correspond to the value of Disposition header field that doesn't correspond to the value of
Content-Type header field. Content-Type header field.
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
3 Security Considerations 3 Security Considerations
The security threats that applications must address when implementing The security threats that applications must address when implementing
iTIP are detailed in [iTIP]. In particular two spoofing threats are iTIP are detailed in [iTIP]. In particular two spoofing threats are
identified in [iTIP]: Spoofing the "Organizer", and Spoofing an identified in [iTIP]: Spoofing the "Organizer", and Spoofing an
"Attendee". To address these threats, the originator of an iCalendar "Attendee". To address these threats, the originator of an iCalendar
object must be authenticated by a recipient. Once authenticated, a object must be authenticated by a recipient. Once authenticated, a
determination can be made as to whether or not the originator is determination can be made as to whether or not the originator is
authorized to perform the requested operation. Compliant applications authorized to perform the requested operation. Compliant applications
MUST support signing and encrypting text/calendar body parts using a MUST support signing and encrypting text/calendar body parts using a
mechanism based on Security Multiparts for MIME [RFC-1847] to mechanism based on Security Multiparts for MIME [RFC-1847] to
facilitate the authentication of the originator of the iCalendar facilitate the authentication of the originator of the iCalendar
object. The steps for processing a signed iMIP message are described object. The steps for processing a signed iMIP message are described
below: below:
1. The iCalendar object MUST be signed by the "Organizer" sending an 1. The iCalendar object MUST be signed by the "Organizer" sending an
update/initial request or the "Attendee" sending a reply. <<Or the update/initial request; the "Attendee" sending a reply; or another
person sending on their behalf? Clearly if somebody else is sending ("uninvited") CU, who was forwarded a REQUEST, sending a reply. <<Or
the invitation, she can't sign using the key belonging to the the person sending on their behalf? Clearly if somebody else is
sending the invitation, she can't sign using the key belonging to the
organizer>> organizer>>
2. Using the security mechanism compliant with [RFC-1847], determine 2. Using the security mechanism compliant with [RFC-1847], determine
who signed the iCalendar object. This is the "signer". Note that the who signed the iCalendar object. This is the "signer". Note that the
signer is not necessarily the person sending an e-mail message since signer is not necessarily the person sending an e-mail message since
an e-mail message can be forwarded. an e-mail message can be forwarded.
3. Correlate the signer to either an "ATTENDEE" property or to the 3. Correlate the signer to either an "ATTENDEE" property or to the
"ORGANIZER" property in the iCalendar object, based on the method and "ORGANIZER" property in the iCalendar object, based on the method and
the calendar component specified in the iCalendar object, as defined the calendar component specified in the iCalendar object, as defined
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5. If all the above conditions are met, the message can be processed. 5. If all the above conditions are met, the message can be processed.
[RFC-1847] signing also protects against malicious changes in [RFC-1847] signing also protects against malicious changes in
transit. transit.
If calendar confidentiality is required by the sender, signed iMIP If calendar confidentiality is required by the sender, signed iMIP
messages SHOULD be encrypted by a mechanism based on Security messages SHOULD be encrypted by a mechanism based on Security
Multiparts for MIME [RFC-1847]. Multiparts for MIME [RFC-1847].
Once a signed and/or encrypted iMIP message is received and Once a signed and/or encrypted iMIP message is received and
successfully verified (as detailed above) by a CUA, the CUA SHOULD
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
successfully verified (as detailed above) by a CUA, the CUA SHOULD
remember whether the sender of the message is using signing and/or remember whether the sender of the message is using signing and/or
encrypting. If an unsigned iMIP message is received from the same encrypting. If an unsigned iMIP message is received from the same
sender later on, the receiving CUA SHOULD warn the user about a sender later on, the receiving CUA SHOULD warn the receiving user
possible man-in-the-middle attack and SHOULD ignore the message, about a possible man-in-the-middle attack and SHOULD ignore the
unless explicitly overriden by the user. <<Should it also try to message, unless explicitly overridden by the user. <<Should it also
notify the other end?>> try to notify the other end?>>
Implementations MAY provide means for users to disable signing and Implementations MAY provide means for users to disable signing and
encrypting. encrypting.
It is possible to receive iMIP messages sent by someone working on It is possible to receive iMIP messages sent by someone working on
behalf of another "Calendar User". This is determined by examining behalf of another "Calendar User". This is determined by examining
the "sent-by" parameter in the relevant "ORGANIZER" or "ATTENDEE" the "sent-by" parameter in the relevant "ORGANIZER" or "ATTENDEE"
property. [iCAL] and [iTIP] provide no mechanism to verify that a property. [iCAL] and [iTIP] provide no mechanism to verify that a
"Calendar User" has authorized someone else to work on their behalf. "Calendar User" has authorized someone else to work on their behalf.
To address this security issue, implementations MUST provide To address this security issue, implementations MUST provide
mechanisms for the "Calendar Users" to make that decision before mechanisms for the "Calendar Users" to make that decision before
applying changes from someone working on behalf of a "Calendar User". applying changes from someone working on behalf of a "Calendar User".
One way to achieve this is to reject iMIP messages sent by users One way to achieve this is to reject iMIP messages sent by users
other than the "ORGANIZER" or the "ATTENDEE"s. other than the "ORGANIZER" or the "ATTENDEE"s.
A security consideration associated with use of Content-Disposition A security consideration associated with use of Content-Disposition
header field is described in section 2.6. header field is described in section 2.6.
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
4 Examples 4 Examples
4.1 Single Component With An ATTACH Property 4.1 Single Component With An ATTACH Property
This minimal message shows how an iCalendar object references an This minimal message shows how an iCalendar object references an
attachment. The attachment is accessible via its URL. attachment. The attachment is accessible via its URL.
From: sman@netscape.example.com From: sman@netscape.example.com
To: stevesil@microsoft.example.com To: stevesil@microsoft.example.com
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Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: text/calendar; method=REQUEST; charset=US-ASCII Content-Type: text/calendar; method=REQUEST; charset=US-ASCII
Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit
BEGIN:VCALENDAR BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST METHOD:REQUEST
VERSION:2.0 VERSION:2.0
BEGIN:VEVENT BEGIN:VEVENT
ORGANIZER:mailto:sman@netscape.example.com ORGANIZER:mailto:sman@netscape.example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:sman@netscape.example.com ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:mailto:sman@netscape.example.com
ATTENDEE;RSVP=YES:mailto:stevesil@microsoft.example.com ATTENDEE;RSVP=YES:mailto:stevesil@microsoft.example.com
DTSTAMP:19970611T190000Z DTSTAMP:19970611T190000Z
DTSTART:19970701T210000Z DTSTART:19970701T210000Z
DTEND:19970701T230000Z DTEND:19970701T230000Z
SUMMARY:Phone Conference SUMMARY:Phone Conference
DESCRIPTION:Please review the attached document. DESCRIPTION:Please review the attached document.
UID:calsvr.example.com-873970198738777 UID:calsvr.example.com-873970198738777
ATTACH:ftp://ftp.bar.example.com/pub/docs/foo.doc ATTACH:ftp://ftp.bar.example.com/pub/docs/foo.doc
STATUS:CONFIRMED STATUS:CONFIRMED
END:VEVENT END:VEVENT
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From: foo1@example.com From: foo1@example.com
To: foo2@example.com To: foo2@example.com
Subject: Phone Conference Subject: Phone Conference
Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: multipart/alternative;boundary="01BD3665.3AF0D360" Content-Type: multipart/alternative;boundary="01BD3665.3AF0D360"
--01BD3665.3AF0D360 --01BD3665.3AF0D360
Content-Type: text/plain;charset=us-ascii Content-Type: text/plain;charset=us-ascii
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit
This is an alternative representation of a TEXT/CALENDAR MIME Object This is an alternative representation of a TEXT/CALENDAR MIME Object
When: 7/1/1997 10:00AM PDT - 7/1/97 10:30AM PDT When: 7/1/1997 10:00AM PDT - 7/1/97 10:30AM PDT
Where: Where:
Organizer: foo1@example.com Organizer: foo1@example.com
Summary: Phone Conference Summary: Phone Conference
--01BD3665.3AF0D360 --01BD3665.3AF0D360
Content-Type: text/calendar; method=REQUEST; charset=US-ASCII Content-Type: text/calendar; method=REQUEST; charset=US-ASCII
Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit
BEGIN:VCALENDAR BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST METHOD:REQUEST
VERSION:2.0 VERSION:2.0
BEGIN:VEVENT BEGIN:VEVENT
ORGANIZER:mailto:foo1@example.com ORGANIZER:mailto:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:foo1@example.com ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:mailto:foo1@example.com
ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo2@example.com ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo2@example.com
DTSTAMP:19970611T190000Z DTSTAMP:19970611T190000Z
DTSTART:19970701T170000Z DTSTART:19970701T170000Z
DTEND:19970701T173000Z DTEND:19970701T173000Z
SUMMARY:Phone Conference SUMMARY:Phone Conference
UID:calsvr.example.com-8739701987387771 UID:calsvr.example.com-8739701987387771
SEQUENCE:0 SEQUENCE:0
STATUS:CONFIRMED STATUS:CONFIRMED
END:VEVENT END:VEVENT
END:VCALENDAR END:VCALENDAR
skipping to change at page 14, line 5 skipping to change at page 14, line 5
From: foo1@example.com From: foo1@example.com
To: foo2@example.com To: foo2@example.com
Subject: Phone Conference Subject: Phone Conference
Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: multipart/related; boundary="boundary-example-1" Content-Type: multipart/related; boundary="boundary-example-1"
--boundary-example-1 --boundary-example-1
Content-Type: text/calendar; method=REQUEST; charset=US-ASCII Content-Type: text/calendar; method=REQUEST; charset=US-ASCII
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="event.vcs" Content-Disposition: attachment; filename="event.ics"
BEGIN:VCALENDAR BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST METHOD:REQUEST
VERSION:2.0 VERSION:2.0
BEGIN:VEVENT BEGIN:VEVENT
ORGANIZER:mailto:foo1@example.com ORGANIZER:mailto:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:foo1@example.com ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:mailto:foo1@example.com
ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo2@example.com ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo2@example.com
DTSTAMP:19970611T190000Z DTSTAMP:19970611T190000Z
DTSTART:19970701T180000Z DTSTART:19970701T180000Z
DTEND:19970701T183000Z DTEND:19970701T183000Z
SUMMARY:Phone Conference SUMMARY:Phone Conference
UID:calsvr.example.com-8739701987387771 UID:calsvr.example.com-8739701987387771
ATTACH:cid:123456789@example.com ATTACH:cid:123456789@example.com
SEQUENCE:0 SEQUENCE:0
STATUS:CONFIRMED STATUS:CONFIRMED
END:VEVENT END:VEVENT
skipping to change at page 14, line 52 skipping to change at page 14, line 52
Multiple iCalendar components of the same type can be included in the Multiple iCalendar components of the same type can be included in the
iCalendar object when the METHOD is the same for each component. iCalendar object when the METHOD is the same for each component.
From: foo1@example.com From: foo1@example.com
To: foo2@example.com To: foo2@example.com
Subject: Summer Company Holidays Subject: Summer Company Holidays
Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: text/calendar; method=PUBLISH; charset=US-ASCII Content-Type: text/calendar; method=PUBLISH; charset=US-ASCII
Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="event.vcs" Content-Disposition: attachment; filename="event.ics"
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
BEGIN:VCALENDAR BEGIN:VCALENDAR
PRODID:-//ACME/DESKTOPCALENDAR//EN PRODID:-//ACME/DESKTOPCALENDAR//EN
METHOD:PUBLISH METHOD:PUBLISH
VERSION:2.0 VERSION:2.0
BEGIN:VEVENT BEGIN:VEVENT
ORGANIZER:MAILTO:FOO1@EXAMPLE.COM ORGANIZER:MAILTO:FOO1@EXAMPLE.COM
DTSTAMP:19970611T150000Z DTSTAMP:19970611T150000Z
DTSTART:19970701T150000Z DTSTART:19970701T150000Z
DTEND:19970701T230000Z DTEND:19970701T230000Z
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To: foo2@example.com To: foo2@example.com
Subject: Phone Conference Subject: Phone Conference
Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: multipart/mixed;boundary="--FEE3790DC7E35189CA67CE2C" Content-Type: multipart/mixed;boundary="--FEE3790DC7E35189CA67CE2C"
This is a multi-part message in MIME format. This is a multi-part message in MIME format.
----FEE3790DC7E35189CA67CE2C ----FEE3790DC7E35189CA67CE2C
Content-Type: text/calendar; method=REQUEST; charset=US-ASCII Content-Type: text/calendar; method=REQUEST; charset=US-ASCII
Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="event1.vcs" Content-Disposition: attachment; filename="event1.ics"
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
BEGIN:VCALENDAR BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST METHOD:REQUEST
VERSION:2.0 VERSION:2.0
BEGIN:VEVENT BEGIN:VEVENT
ORGANIZER:mailto:foo1@example.com ORGANIZER:mailto:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:foo1@example.com ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:mailto:foo1@example.com
ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo2@example.com ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo2@example.com
DTSTAMP:19970611T190000Z DTSTAMP:19970611T190000Z
DTSTART:19970701T210000Z DTSTART:19970701T210000Z
DTEND:19970701T230000Z DTEND:19970701T230000Z
SUMMARY:Phone Conference SUMMARY:Phone Conference
DESCRIPTION:Discuss what happened at the last meeting DESCRIPTION:Discuss what happened at the last meeting
UID:calsvr.example.com-8739701987387772 UID:calsvr.example.com-8739701987387772
SEQUENCE:0 SEQUENCE:0
STATUS:CONFIRMED STATUS:CONFIRMED
END:VEVENT END:VEVENT
END:VCALENDAR END:VCALENDAR
----FEE3790DC7E35189CA67CE2C ----FEE3790DC7E35189CA67CE2C
Content-Type: text/calendar; method=REQUEST; charset=US-ASCII Content-Type: text/calendar; method=REQUEST; charset=US-ASCII
Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="todo1.vcs" Content-Disposition: attachment; filename="todo1.ics"
BEGIN:VCALENDAR BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN PRODID:-//ACME/DesktopCalendar//EN
METHOD:REQUEST METHOD:REQUEST
VERSION:2.0 VERSION:2.0
BEGIN:VTODO BEGIN:VTODO
DUE:19970701T090000-0700 DUE:19970701T160000Z
ORGANIZER:mailto:foo1@example.com ORGANIZER:mailto:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:mailto:foo1@example.com ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:mailto:foo1@example.com
ATTENDEE;RSVP=YES:mailto:foo2@example.com ATTENDEE;RSVP=YES:mailto:foo2@example.com
SUMMARY:Phone Conference SUMMARY:Phone Conference
DESCRIPTION:Discuss a new location for the company picnic DESCRIPTION:Discuss a new location for the company picnic
UID:calsvr.example.com-td-8739701987387773 UID:calsvr.example.com-td-8739701987387773
SEQUENCE:0 SEQUENCE:0
STATUS:NEEDS ACTION STATUS:NEEDS-ACTION
END:VEVENT END:VEVENT
END:VCALENDAR END:VCALENDAR
----FEE3790DC7E35189CA67CE2C ----FEE3790DC7E35189CA67CE2C
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
4.6 Detailed Components With An ATTACH Property 4.6 Detailed Components With An ATTACH Property
This example shows the format of a message containing a group meeting This example shows the format of a message containing a group meeting
between three individuals. The multipart/related encapsulation is between three individuals. The multipart/related encapsulation is
used because the iCalendar object contains an ATTACH property that used because the iCalendar object contains an ATTACH property that
uses a CID to reference the attachment. uses a CID to reference the attachment.
From: foo1@example.com From: foo1@example.com
MIME-Version: 1.0 MIME-Version: 1.0
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When: 7/1/1997 10:00PM PDT- 7/1/97 10:30 PM PDT When: 7/1/1997 10:00PM PDT- 7/1/97 10:30 PM PDT
Where: Where:
Organizer: foo1@example.com Organizer: foo1@example.com
Summary: Let's discuss the attached document Summary: Let's discuss the attached document
----00FEE3790DC7E35189CA67CE2C00 ----00FEE3790DC7E35189CA67CE2C00
Content-Type: text/calendar; method=REQUEST; charset=US-ASCII; Content-Type: text/calendar; method=REQUEST; charset=US-ASCII;
Component=vevent Component=vevent
Content-Transfer-Encoding: 7bit Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="event.vcs" Content-Disposition: attachment; filename="event.ics"
BEGIN:VCALENDAR BEGIN:VCALENDAR
PRODID:-//ACME/DesktopCalendar//EN PRODID:-//ACME/DesktopCalendar//EN
PROFILE:REQUEST METHOD:REQUEST
PROFILE-VERSION:1.0
VERSION:2.0 VERSION:2.0
BEGIN:VEVENT BEGIN:VEVENT
ORGANIZER:foo1@example.com ORGANIZER:foo1@example.com
ATTENDEE;ROLE=CHAIR;ATTSTAT=ACCEPTED:foo1@example.com ATTENDEE;ROLE=CHAIR;PARTSTAT=ACCEPTED:foo1@example.com
ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo2@example.com ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo2@example.com
ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo3@example.com ATTENDEE;RSVP=YES;CUTYPE=INDIVIDUAL:mailto:foo3@example.com
DTSTAMP:19970611T190000Z DTSTAMP:19970611T190000Z
DTSTART:19970621T170000Z DTSTART:19970621T170000Z
DTEND:199706211T173000Z DTEND:199706211T173000Z
SUMMARY:Let's discuss the attached document SUMMARY:Let's discuss the attached document
UID:calsvr.example.com-873970198738777-8aa UID:calsvr.example.com-873970198738777-8aa
ATTACH:cid:calsvr.example.com-12345aaa
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
ATTACH:cid:calsvr.example.com-12345aaa
SEQUENCE:0 SEQUENCE:0
STATUS:CONFIRMED STATUS:CONFIRMED
END:VEVENT END:VEVENT
END:VCALENDAR END:VCALENDAR
----00FEE3790DC7E35189CA67CE2C00 ----00FEE3790DC7E35189CA67CE2C00
----FEE3790DC7E35189CA67CE2C ----FEE3790DC7E35189CA67CE2C
Content-Type: application/msword; name="FieldReport.doc" Content-Type: application/msword; name="FieldReport.doc"
Content-Transfer-Encoding: base64 Content-Transfer-Encoding: base64
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The [iCAL] specification makes frequent use of the URI for data types The [iCAL] specification makes frequent use of the URI for data types
in properties such as "DESCRIPTION", "ATTACH", "CONTACT" and others. in properties such as "DESCRIPTION", "ATTACH", "CONTACT" and others.
Two forms of URIs are Message ID (MID) and Content ID (CID). These Two forms of URIs are Message ID (MID) and Content ID (CID). These
are defined in [RFC-2392]. Although [RFC-2392] allows referencing are defined in [RFC-2392]. Although [RFC-2392] allows referencing
messages or MIME body parts in other MIME entities or stores, it is messages or MIME body parts in other MIME entities or stores, it is
strongly recommended that iMIP implementations include all referenced strongly recommended that iMIP implementations include all referenced
messages and body parts in a single MIME entity. Simply put, if an messages and body parts in a single MIME entity. Simply put, if an
iCalendar object contains CID or MID references to other messages or iCalendar object contains CID or MID references to other messages or
body parts, implementations should ensure that these messages and/or body parts, implementations should ensure that these messages and/or
body parts are transmitted with the iCalendar object. If they are not body parts are transmitted with the iCalendar object. If they are
there is no guarantee that the receiving CUA will have the access or not, there is no guarantee that the receiving CUA will have the
the authorization to view those objects. access or the authorization to view those objects.
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
6 IANA Considerations 6 IANA Considerations
Registration of text/calendar MIME Media Type is done in [iCal]. Registration of text/calendar MIME Media Type is done in [iCal].
This document doesn't require any additional actions from IANA. This document doesn't require any additional actions from IANA.
7 References 7 References
7.1 Normative References 7.1 Normative References
[iCAL] Desruisseaux, B., (Ed.), "Internet Calendaring and [iCAL] Desruisseaux, B., (Ed.), "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)", work in progress, Scheduling Core Object Specification (iCalendar)", RFC 5545.
draft-ietf-calsify-rfc2445bis-XX.txt (Updated RFC 2445)
[iTIP] Daboo, C., "iCalendar Transport-Independent [iTIP] Daboo, C., "iCalendar Transport-Independent
Interoperability Protocol (iTIP)", work in progress, draft-ietf- Interoperability Protocol (iTIP)", work in progress, draft-ietf-
calsify-2446bis-XX.txt (Updates RFC 2446) calsify-2446bis-XX.txt (Updates RFC 2446)
[RFC-5322] Resnick, P., "Internet Message Format", RFC 5322, October [RFC-5322] Resnick, P., "Internet Message Format", RFC 5322, October
2008. 2008.
[RFC-1847] Galvin, J., Murphy, S., Crocker, S. and N. Freed, [RFC-1847] Galvin, J., Murphy, S., Crocker, S. and N. Freed,
"Security Multiparts for MIME: Multipart/Signed and "Security Multiparts for MIME: Multipart/Signed and
skipping to change at page 20, line 4 skipping to change at page 19, line 54
[UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 10646", [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
STD 63, RFC 3629, November 2003. STD 63, RFC 3629, November 2003.
7.2 Informative References 7.2 Informative References
[8BITMIME] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D. [8BITMIME] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
Crocker, "SMTP Service Extension for 8bit-MIMEtransport", RFC 1652, Crocker, "SMTP Service Extension for 8bit-MIMEtransport", RFC 1652,
July 1994. July 1994.
[RFC-2047] Moore, K., "Multipurpose Internet Mail Extensions (MIME) - [RFC-2047] Moore, K., "Multipurpose Internet Mail Extensions (MIME) -
Part Three: Message Header Extensions for Non-ASCII Text", RFC 2047,
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
Part Three: Message Header Extensions for Non-ASCII Text", RFC 2047,
November 1996. November 1996.
[RFC-2049] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC-2049] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Five: Conformance Criteria and Examples", RFC Extensions (MIME) Part Five: Conformance Criteria and Examples", RFC
2049, November 1996. 2049, November 1996.
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
8 Authors' Addresses 8 Authors' Addresses
Alexey Melnikov (editor) Alexey Melnikov (editor)
Isode Ltd Isode Ltd
5 Castle Business Village 5 Castle Business Village
36 Station Road 36 Station Road
Hampton, Middlesex TW12 2BX Hampton, Middlesex TW12 2BX
UK UK
Email: Alexey.Melnikov@isode.com Email: Alexey.Melnikov@isode.com
RFC 2447bis iMIP September 2009 RFC 2447bis iMIP October 2009
Appendix A. Changes since RFC 2447. Appendix A. Changes since RFC 2447.
Updated references. Split them into Normative and Informative. Updated references. Split them into Normative and Informative.
Updated examples to use example.com/example.net domains. Updated examples to use example.com/example.net domains.
Corrected usage of RFC 2119 language. Corrected usage of RFC 2119 language.
Clarified that charset=UTF-8 is required, unless the calendar can be Clarified that charset=UTF-8 is required, unless the calendar can be
entirely represented in US-ASCII. entirely represented in US-ASCII.
Clarified that 7-bit content transfer encodings should be used unless Clarified that 7-bit content transfer encodings should be used unless
the calendar object is known to be transferred over 8-bit clean the calendar object is known to be transferred over 8-bit clean
transport. transport.
Clarified that file extension specified in the Content-Disposition Clarified that file extension specified in the Content-Disposition
header field is not to be used to override the Content-Type MIME header field is not to be used to override the Content-Type MIME
type. type.
Disallow use of "multiple/alternative" for slightly different Disallow use of "multipart/alternative" for slightly different
representations of the same calendar. representations of the same calendar.
Fixed examples with ATTENDEE property to use "CUTYPE=" instead of Fixed examples with ATTENDEE property to use "CUTYPE=" instead of
"TYPE=". "TYPE=".
Various editorial changes to the Security Considerations section. Improved Security Considerations section.
Multiple editorial changes to different sections of the document.
<<TBD>> <<TBD>>
Appendix B. Acknowledgements
<<RFC Editor: feel free to move this section elsewhere.>>
The editor of this document wish to thank Frank Dawson, Steve Mansour
and Steve Silverberg, the original authors of RFC 2447, as well as
the following individuals who have participated in the drafting,
review and discussion of this memo:
Reinhold Kainhofer, Cyrus Daboo, Bernard Desruisseaux, Eliot Lear.
 End of changes. 59 change blocks. 
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