XMPP Instant Messaging From: http://www.ietf.org/internet-drafts/draft-miller-xmpp-im-01.txt Reference: draft-miller-xmpp-im-01 ------------------------------------------------------------------------ Network Working Group J. Miller Internet-Draft P. Saint-Andre Expires: April 23, 2003 Jabber Software Foundation October 23, 2002 XMPP Instant Messaging draft-miller-xmpp-im-01 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 23, 2003. Copyright Notice Copyright (C) The Internet Society (2002). All Rights Reserved. Abstract This document describes the specific extensions to and applications of the eXtensible Messaging and Presence Protocol (XMPP) that are necessary to create a basic instant messaging and presence application (specificlaly, an application that is compatible with the open-source Jabber instant messaging system). Miller & Saint-Andre Expires April 23, 2003 [Page 1] Internet-Draft XMPP Instant Messaging October 2002 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4 1.4 Conventions Used in this Document . . . . . . . . . . . . . 4 1.5 Discussion Venue . . . . . . . . . . . . . . . . . . . . . . 5 1.6 Intellectual Property Notice . . . . . . . . . . . . . . . . 5 2. Registration . . . . . . . . . . . . . . . . . . . . . . . . 6 2.1 Registration Data Flow . . . . . . . . . . . . . . . . . . . 6 2.2 Cancellation Data Flow . . . . . . . . . . . . . . . . . . . 7 2.3 Definition of the jabber:iq:register Namespace . . . . . . . 8 2.3.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.3.2 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3. Authentication . . . . . . . . . . . . . . . . . . . . . . . 11 3.1 Authentication Using SASL . . . . . . . . . . . . . . . . . 11 3.2 Authentication Using jabber:iq:auth . . . . . . . . . . . . 12 3.3 Definition of the jabber:iq:auth Namespace . . . . . . . . . 13 3.3.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.3.2 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.3.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4. Exchanging Messages . . . . . . . . . . . . . . . . . . . . 15 4.1 Specifying an Intended Recipient . . . . . . . . . . . . . . 15 4.2 Specifying the Sender . . . . . . . . . . . . . . . . . . . 15 4.3 Specifying a Message Type . . . . . . . . . . . . . . . . . 15 4.4 Specifying a Message Subject . . . . . . . . . . . . . . . . 16 4.5 Specifying a Message Thread . . . . . . . . . . . . . . . . 16 4.6 Specifying a Message Body . . . . . . . . . . . . . . . . . 17 4.7 Specifying Additional Information . . . . . . . . . . . . . 17 4.8 Message-Related Errors . . . . . . . . . . . . . . . . . . . 18 5. Exchanging Presence Information . . . . . . . . . . . . . . 19 5.1 Node and Host Responsibilities . . . . . . . . . . . . . . . 19 5.2 Sending Initial Presence . . . . . . . . . . . . . . . . . . 19 5.3 Specifying Availability Status . . . . . . . . . . . . . . . 20 5.4 Specifying Detailed Status Information . . . . . . . . . . . 20 5.5 Probing for Presence . . . . . . . . . . . . . . . . . . . . 20 5.6 Sending Final Presence . . . . . . . . . . . . . . . . . . . 20 6. Managing Subscriptions . . . . . . . . . . . . . . . . . . . 21 6.1 Requesting a Subscription . . . . . . . . . . . . . . . . . 21 6.2 Handling a Subscription Request . . . . . . . . . . . . . . 21 6.3 Cancelling a Subscription from Another Entity . . . . . . . 22 6.4 Unsubscribing from Another Entity's Presence . . . . . . . . 22 7. Managing One's Roster . . . . . . . . . . . . . . . . . . . 23 7.1 Receiving One's Roster on Login . . . . . . . . . . . . . . 23 7.2 Adding a Roster Item . . . . . . . . . . . . . . . . . . . . 23 7.3 Deleting a Roster Item . . . . . . . . . . . . . . . . . . . 24 Miller & Saint-Andre Expires April 23, 2003 [Page 2] Internet-Draft XMPP Instant Messaging October 2002 7.4 Definition of the jabber:iq:roster Namespace . . . . . . . . 25 7.4.1 Children . . . . . . . . . . . . . . . . . . . . . . . . . . 25 7.4.2 DTD . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 7.4.3 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 8. Routing and Delivery Guidelines . . . . . . . . . . . . . . 28 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . 29 10. Security Considerations . . . . . . . . . . . . . . . . . . 30 10.1 Secure Identity and Encryption . . . . . . . . . . . . . . . 30 10.2 Node Connections . . . . . . . . . . . . . . . . . . . . . . 30 References . . . . . . . . . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 31 Full Copyright Statement . . . . . . . . . . . . . . . . . . 33 Miller & Saint-Andre Expires April 23, 2003 [Page 3] Internet-Draft XMPP Instant Messaging October 2002 1. Introduction 1.1 Scope The core features of the XMPP protocol (XMPP Core [2]) provide the building blocks for many types of near-real-time applications, which may be layered on top of the core by sending XML chunks that are scoped by specific XML namespaces. This document describes the specific extensions to and applications of XMPP Core that are used to create the basic functionality expected of an instant messaging and presence application as defined in RFC 2778 [8] and RFC 2779 [9]. Many other functionality areas are defined in the Jabber protocol, including service discovery, multi-user chat, search, remote procedure calls, data gathering and forms submission, encryption, feature negotiation, message composing events, message expiration, and file transfer; however, such functionality is not described herein. 1.2 Terminology This document inherits the terminology defined in XMPP Core [2]. 1.3 Requirements For the purposes of this document, we stipulate that a basic instant messaging and presence application needs to enable a node to perform the following functionality: o Register an account with a host o Authenticate with a host o Exchange messages with other nodes o Exchange presence information with other nodes o Manage subscriptions to and from other nodes o Manage the items in the node's roster (a.k.a. contact list) 1.4 Conventions Used in this Document The capitalized 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 RFC 2119 [1]. Miller & Saint-Andre Expires April 23, 2003 [Page 4] Internet-Draft XMPP Instant Messaging October 2002 1.5 Discussion Venue The authors welcome discussion and comments related to the topics presented in this document, preferably on the "xmppwg@jabber.org" mailing list (archives and subscription information are available at http://www.jabber.org/cgi-bin/mailman/listinfo/xmppwg/). 1.6 Intellectual Property Notice This document is in full compliance with all provisions of Section 10 of RFC 2026. Parts of this specification use the term "jabber" for identifying URI schemes, namespaces, and other protocol syntax. Jabber[tm] is a registered trademark of Jabber, Inc. Jabber, Inc. grants permission to the IETF for use of Jabber trademark in association with this specification and its successors, if any. Miller & Saint-Andre Expires April 23, 2003 [Page 5] Internet-Draft XMPP Instant Messaging October 2002 2. Registration Registering with a host is necessary in order for a node to engage in any desired functionality. Certainly such registration MAY (and frequently does) occur outside the context of an instant messaging and presence application. However, XMPP also enables a node to register with a host within the context of an IM system. This functionality is enabled by sending and receiving IQ chunks in a request-response pattern, where the IQ chunks contain elements in the jabber:iq:register namespace. 2.1 Registration Data Flow Step 1: Node queries host regarding information that is required in order to register: Step 2: Host responds with the required registration fields: Choose a username and password to register with this service. Note: the node is REQUIRED to provide information for all of the elements (other than ) contained in the IQ result. (Note also that the XML chunk shown above does not include a 'to' attribute, since the connected socket does not yet have an account.) Miller & Saint-Andre Expires April 23, 2003 [Page 6] Internet-Draft XMPP Instant Messaging October 2002 Step 3: Node provides required information: juliet@capulet.com R0m30 juliet Step 4: Host informs node of successful registration: Step 4 (alt): Host informs node of failed registration: Not Acceptable 2.2 Cancellation Data Flow The jabber:iq:register namespace also makes it possible for a user to cancel a registration with a host by sending a element as shown below. Step 1: Node sends request to unregister: Miller & Saint-Andre Expires April 23, 2003 [Page 7] Internet-Draft XMPP Instant Messaging October 2002 Step 2: Host informs node of successful unregistration: 2.3 Definition of the jabber:iq:register Namespace 2.3.1 Children While numerous fields are available for use in the jabber:iq:register namespace, only those fields (other than ) sent from the host in an IQ result are REQUIRED in order to register. The officially-recognized fields available for use are as follows: o instructions o username o password o name o email o address o city o state o zip o phone o url o date o misc o text o remove - request to unregister (sent only in an IQ set) Miller & Saint-Andre Expires April 23, 2003 [Page 8] Internet-Draft XMPP Instant Messaging October 2002 2.3.2 DTD 2.3.3 Schema Miller & Saint-Andre Expires April 23, 2003 [Page 9] Internet-Draft XMPP Instant Messaging October 2002 Miller & Saint-Andre Expires April 23, 2003 [Page 10] Internet-Draft XMPP Instant Messaging October 2002 3. Authentication In order to gain access to the network of XMPP-compliant applications and thus engage in standard IM functionality such as exchanging messages and presence, a node must authenticate with a host. The preferred authentication method is SASL. Authentication using the older jabber:iq:auth method is OPTIONAL and MAY be used if a node does not support SASL. 3.1 Authentication Using SASL If a node is capable of authenticating with SASL, it MUST include the agreed-upon SASL namespace within the opening element with which it initiated communications with the host. For the protocol describing how a node authenticates with a host, refer to XMPP Core [2]. Once a node has authenticated its streams with a host, it MUST provide a resource associated with the connection. This is accomplished by means of the jabber:iq:auth namespace. The protocol for doing so is described below. Step 1: Node queries host regarding information that is still required to begin a session: juliet Step 2: Host responds with the required fields (in this case, only the username and resource): juliet Miller & Saint-Andre Expires April 23, 2003 [Page 11] Internet-Draft XMPP Instant Messaging October 2002 Step 3: Node sends resource information: juliet balcony Step 4: Host informs node of successful session initiation: 3.2 Authentication Using jabber:iq:auth Earlier iterations of XMPP contained a client-server authentication protocol that was enforced after the stream was negotiated; this protocol, which uses the jabber:iq:auth namespace, is described for completeness in this section. The jabber:iq:auth namespace provides two things: (1) a simple way for a node to authenticate with a host and (2) a way to create a resource representing a specific connection or session associated with the node. The following is the data flow for a complete example of a node authenticating with a host. Step 1: Node queries host regarding information that is required in order to authenticate: juliet Miller & Saint-Andre Expires April 23, 2003 [Page 12] Internet-Draft XMPP Instant Messaging October 2002 Step 2: Host responds with the required authentication fields: juliet Step 3: Node sends authentication information (encrypted password): juliet 64d60e40febe09264c52bc9cbddd5dd1147fae97 balcony Step 4: Host informs node of successful authentication: Step 4 (alt): Host informs node of failed authentication: Unauthorized 3.3 Definition of the jabber:iq:auth Namespace 3.3.1 Children o username - the unique username for this node (usually an IM user). o password - the secret key or passphrase for the node's access to the host. o digest - the concatenation of the stream id and the password, encrypted according to the SHA1 Secure Hash Algorithm [3] and represented as all lowercase hex. o resource - unique value to represent current connection. Miller & Saint-Andre Expires April 23, 2003 [Page 13] Internet-Draft XMPP Instant Messaging October 2002 3.3.2 DTD 3.3.3 Schema Miller & Saint-Andre Expires April 23, 2003 [Page 14] Internet-Draft XMPP Instant Messaging October 2002 4. Exchanging Messages Exchanging messages is simple within XMPP: using the data element, a node can send a message to any other node (or, more generally, any entity). 4.1 Specifying an Intended Recipient A node MAY specify an intended recipient for the message by providing an appropriate JID in the 'to' attribute of the element. Normally, the value of the 'to' attribute specifies an entity other than the sending node (for exceptions, see the next paragraph). The intended recipient MAY be any valid JID (e.g., a node on the same host, a node on a different host, the host itself, or another host). If no 'to' address is specified, it is implied that the message is addressed to the sending node itself (i.e., the node@host sending the chunk); furthermore, a message explicitly or implicitly addressed to the sending node itself is processed by the host on behalf of that node. A message addressed to a specific connected resource associated with the sending node is delivered to that node@host/ resource (which MAY be different from the connected resource that generated the message). 4.2 Specifying the Sender A node MAY specify the sender's address by including a 'from' attribute in the message chunk, and MAY specify any resource or full JID in that 'from' attribute. However, a host MUST verify that the value of the 'from' attribute matches the node@host/resource of the connected resource that generated the message chunk. If no 'from' attribute is included, the host MUST add the valid and authenticated from address of the connected resource sending the chunk (i.e., the node@host/resource). 4.3 Specifying a Message Type As mentioned in XMPP Core [2], there are several defined types of messages (specified by means of a 'type' attribute within the element). In the context of an instant messaging application, a node MAY include a message type in order to capture the conversational context of the message, thus providing a hint regarding presentation (e.g., in a GUI). If no type is set or if the type is set to a value other than those specified here, the value SHOULD be defaulted to "normal" by the host. If included, the 'type' attribute SHOULD have one of the following values: o normal - A single message Miller & Saint-Andre Expires April 23, 2003 [Page 15] Internet-Draft XMPP Instant Messaging October 2002 o chat - A message sent in the context of two-way chat between two entities o groupchat - A message sent in the context of multi-user chat among multiple entities o headline - A message that represents one of a list of items (e.g., in a news feed or information ticker) o error - A message returned to a sender specifying an error associated with a previous message sent by the sender to an intended recipient (for a full list of error messages, see XMPP Core [2]) 4.4 Specifying a Message Subject A message chunk MAY contain a child element specifying the subject of the message. The subject MAY NOT contain mixed content. A message with a subject: Imploring Wherefore art thou, Romeo? 4.5 Specifying a Message Thread A message chunk MAY contain a child element specifying the thread of the message for the purpose of tracking a conversation thread. The content of the element is a random string that is generated by the sender; this string MAY be copied back to the sender in subsequent replies. If included, the element MUST have no attributes and MAY NOT contain mixed content. Miller & Saint-Andre Expires April 23, 2003 [Page 16] Internet-Draft XMPP Instant Messaging October 2002 A simple threaded conversation: Art thou not Romeo, and a Montague? 283461923759234 Neither, fair saint, if either thee dislike. 283461923759234 How cam'st thou hither, tell me, and wherefore? 283461923759234 4.6 Specifying a Message Body A message chunk MAY (and usually will) contain a child element specifying the body of the message. The body MAY NOT contain mixed content. If it is necessary to provide the message body in an alternate form (e.g., encrypted using the public key infrastructure or formatted using XHTML), the alternate form SHOULD be contained in an appropriately-namespaced child of the element other than the element. 4.7 Specifying Additional Information A element MAY house an element containing content that extends the meaning of the message (e.g., an encrypted form of the message body). In common usage this child element is often the element but MAY be any element. The child element must possess an 'xmlns' namespace declaration (other than those defined for XML streams) that defines all elements contained within the child element. Miller & Saint-Andre Expires April 23, 2003 [Page 17] Internet-Draft XMPP Instant Messaging October 2002 4.8 Message-Related Errors If a message sent by a sender cannot be delivered, a host SHOULD return that message to the sender in a message of type "error" along with an appropriate error message (for a list of error messages, see XMPP Core [2]). A message-related error: Sleep dwell upon thine eyes Sleep dwell upon thine eyes Not Found Miller & Saint-Andre Expires April 23, 2003 [Page 18] Internet-Draft XMPP Instant Messaging October 2002 5. Exchanging Presence Information Exchanging presence information is made relatively simple within XMPP by using the data element. However, we see here a contrast to the handling of messages: although a node MAY send directed presence information to another entity, in general presence information is sent from a node to a host and then broadcasted by the host to any entities that are subscribed to the presence of the sending entity. 5.1 Node and Host Responsibilities When a node connects to a host, it sends an initial element to the host to express default availability. Upon receiving initial presence from a node, the host sends presence probes to any remote entities that are subscribed to that node's presence (as represented in the node's roster) in order to determine if they are available. (The remote host is responsible for responding to the presence probe only when (1) the probing entity has been allowed to access the probed entity's presence, e.g., by server rules or user subscriptions, and (2) the probed entity is available; the probing entity's host then informs the probing entity of the probed entity's last known available presence, for all of the probed entity's resources if applicable.) The host then sends the node's initial presence chunk to any subscribed entities that are available. Throughout the active session of a connected resource associated with the node, the host is responsible for broadcasting any changes in the availability status of the connected resource to the subscribed entities that are available, so that such entities are apprised of availability changes. Finally, the host MUST notify all of the subscribed and available entities when a connected resource becomes unavailable. 5.2 Sending Initial Presence Upon authenticating, a node SHOULD send initial presence to its host indicating that the connected resource is available for communications. Initial presence sent from node to host: Miller & Saint-Andre Expires April 23, 2003 [Page 19] Internet-Draft XMPP Instant Messaging October 2002 5.3 Specifying Availability Status A node MAY provide further information about its availability status by using the element. The recognized values for the show element are "away", "chat", "xa", and "dnd". Availability status: away 5.4 Specifying Detailed Status Information In conjunction with the element, a node MAY provide detailed status information by using the element. The content of this element is a natural-language description of the node's current availability status. Detailed status information: dnd Busy fighting the Romans 5.5 Probing for Presence A node or a host MAY probe for the current presence of another entity. A node probing for the presence of another node MUST have permission to view the presence of the probed node. Presence probe: 5.6 Sending Final Presence Upon ending its session with a host, a node SHOULD send a final presence chunk that is explicitly of type unavailable. Sending final presence to express unavailable state: Miller & Saint-Andre Expires April 23, 2003 [Page 20] Internet-Draft XMPP Instant Messaging October 2002 6. Managing Subscriptions In order to protect the privacy of instant messaging users and any other entities, presence and availability information is made available only to other entities that the user has approved. When a user has agreed that another entity may view its presence, the entity is said to have a subscription to the user's presence information. Note well that a subscription lasts across sessions; indeed, it lasts until the subscriber unsubscribes or the subscribee cancels the previously-granted subscription. Subscriptions are completed within XMPP by sending presence chunks containing specially-defined attributes of the element. 6.1 Requesting a Subscription A request to subscribe to another entity's presence is made by sending a presence chunk of type="subscribe". Sending a subscription request: 6.2 Handling a Subscription Request When a node receives a subscription request from another entity, it MAY accept the request by sending a presence chunk of type="subscribed" or decline the request by sending a presence chunk of type="unsubscribed". Accepting a subscription request: Miller & Saint-Andre Expires April 23, 2003 [Page 21] Internet-Draft XMPP Instant Messaging October 2002 Denying a presence subscription request: 6.3 Cancelling a Subscription from Another Entity If a node would like to cancel a previously-granted subscription request, it sends a presence chunk of type="unsubscribed". Cancelling a previously granted subscription request: 6.4 Unsubscribing from Another Entity's Presence If a node would like to unsubscribe from the presence of another entity, it sends a presence chunk of type="unsubscribe". Unsubscribing from an entity's presence: Miller & Saint-Andre Expires April 23, 2003 [Page 22] Internet-Draft XMPP Instant Messaging October 2002 7. Managing One's Roster One's list of contacts is called a roster. A roster is stored by the host so that a user may access roster information from any connected resource. 7.1 Receiving One's Roster on Login Upon connecting to the host, a node SHOULD request the roster (however, because receiving the roster may not be desirable for all resources, e.g., a connection with limited bandwidth, the node's request for the roster is OPTIONAL). Node requests current roster from host: Node receives roster from the host: Friends Friends 7.2 Adding a Roster Item At any time, a node MAY add an item to its roster. Miller & Saint-Andre Expires April 23, 2003 [Page 23] Internet-Draft XMPP Instant Messaging October 2002 Node adds a new item: Servants The host is responsible for updating the roster information in persistent storage, and also for pushing that change out to all connected resources for the node using an iq element of type "set". This enables all connected resources to remain in sync with the host- based roster information. Host replies with an IQ result to the sending resource and pushes the updated roster information to all connected resources: Servants Servants 7.3 Deleting a Roster Item At any time, a node MAY delete an item from its roster. Miller & Saint-Andre Expires April 23, 2003 [Page 24] Internet-Draft XMPP Instant Messaging October 2002 Node adds a new item: Servants Note: as with adding a roster item, when deleting a roster item the host is responsible for updating the roster information in persistent storage, and also for pushing that change out to all connected resources for the node using an iq element of type "set". 7.4 Definition of the jabber:iq:roster Namespace 7.4.1 Children A element scoped by the jabber:iq:roster namespace MAY contain zero or more elements. An item element MAY contain the following attributes: o jid - A REQUIRED attribute that contains the complete JID of the contact that this item represents o name - An OPTIONAL attribute that contains a natural-language name for the contact o subscription - The current status of the subscription related to this item. Should be one of the following (all other values are ignored): * none - no subscription. * from - this entity has a subscription to the contact. * to - the contact has a subscription to this entity. * both - subscription is both to and from. * remove - item is to be removed. o ask - An OPTIONAL attribute specifying the current status of a request to this contact. Should be one of the following (all Miller & Saint-Andre Expires April 23, 2003 [Page 25] Internet-Draft XMPP Instant Messaging October 2002 other values are ignored): * subscribe - this entity is asking to subscribe to that contact's presence. * unsubscribe - this entity is asking unsubscribe from that contact's presence. An element MAY contain zero or more instances of the following element: o group - Natural-language name of a user-specified group for the purpose of categorizing contacts into groups. 7.4.2 DTD 7.4.3 Schema Miller & Saint-Andre Expires April 23, 2003 [Page 26] Internet-Draft XMPP Instant Messaging October 2002 Miller & Saint-Andre Expires April 23, 2003 [Page 27] Internet-Draft XMPP Instant Messaging October 2002 8. Routing and Delivery Guidelines XML chunks that are not handled directly by a host (e.g., for the purpose of data storage or rebroadcasting) are routed or delivered to the intended recipient of the chunk as represented by a JID in the 'to' attribute. The following rules apply: o If the JID contains a resource identifier (to="node@host/ resource"), the chunk is delivered first to the resource that exactly matches the resource identifier, or secondarily to a resource that matches partially (e.g., resource "foo" partially matches resource identifier "foobar"). o If the JID contains a resource identifier and there are no matching resources, but there are other connected resources associated with the node, then message chunks are further processed as if no resource is specified (see next item). For all other chunks, the host should return them to the sender with a type of "error" and an appropriate error code (503) and message. o If the JID contains only a node@host and there is at least one connected resource available for the node, the host should deliver the chunk to an appropriate resource based on the availability state, priority, and connect time of the connected resource(s). (Existing XMPP implementations contain some hardcoded rules, based on and most recent connection time, for the routing of such chunks. A more flexible approach to routing would be desirable.) o If the JID contains only a node@host and there are no connected resources available for the node (e.g., an IM user is offline), the host MAY choose to store the chunk (usually only message and presence subscription chunks) on behalf of the node and deliver the chunk when a resource becomes available for that node. Miller & Saint-Andre Expires April 23, 2003 [Page 28] Internet-Draft XMPP Instant Messaging October 2002 9. IANA Considerations The IANA registers "jabber-client" and "jabber-server" as GSS-API [7] service names, as specified in Section 6.1.1. Miller & Saint-Andre Expires April 23, 2003 [Page 29] Internet-Draft XMPP Instant Messaging October 2002 10. Security Considerations For general security considerations, refer to the relevant section of XMPP Core [2]. 10.1 Secure Identity and Encryption Nodes MAY optionally support signing and encrypting messages and presence by using the Public Key Infrastructure (e.g., PGP/GnuPG), with the encrypted or signed data sent in an element within the jabber:x:encrypted or jabber:x:signed namespace. (These are informational protocols approved by the Jabber Software Foundation and are not covered in this document.) Implementations MAY choose to offer MIME-based security services providing message integrity and confidentiality, such as OpenPGP [4] or S/MIME [5]. 10.2 Node Connections The IP address and method of access of nodes MUST never be made available by a host, nor are any connections other than the original host connection required. This helps protect the node's host from direct attack or identification by third parties. Miller & Saint-Andre Expires April 23, 2003 [Page 30] Internet-Draft XMPP Instant Messaging October 2002 References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Miller, J. and P. Saint-Andre, "XMPP Core (draft-miller-jabber- xmpp-core-00, work in progress)", June 2002. [3] World Wide Web Consortium, "Secure Hash Algorithm - Version 1.0", October 1997, . [4] Elkins, M., Del Torto, D., Levien, R. and T. Roessler, "MIME Security with OpenPGP", RFC 3156, August 2001. [5] Ramsdell, B., "S/MIME Version 3 Message Specification", RFC 2633, June 1999. [6] Freier, A., Karlton, P. and P. Kocher, "The SSL Protocol - Version 3.0", November 1996, . [7] Linn, J., "Generic Security Service Application Program Interface, Version 2", RFC 2078, January 1997. [8] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000, . [9] Day, M., Aggarwal, S., Mohr, G. and J. Vincent, "A Model for Presence and Instant Messaging", RFC 2779, February 2000, . Authors' Addresses Jeremie Miller Jabber Software Foundation 1899 Wynkoop Street, Suite 600 Denver, CO 80202 US EMail: jeremie@jabber.org URI: http://www.jabber.org/ Miller & Saint-Andre Expires April 23, 2003 [Page 31] Internet-Draft XMPP Instant Messaging October 2002 Peter Saint-Andre Jabber Software Foundation 1899 Wynkoop Street, Suite 600 Denver, CO 80202 US EMail: stpeter@jabber.org URI: http://www.jabber.org/ Miller & Saint-Andre Expires April 23, 2003 [Page 32] Internet-Draft XMPP Instant Messaging October 2002 Full Copyright Statement Copyright (C) The Internet Society (2002). All Rights Reserved. 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