draft-ietf-mmusic-kmgmt-ext-07.txt		draft-ietf-mmusic-kmgmt-ext-08.txt
	Internet Engineering Task Force J. Arkko		Internet Engineering Task Force J. Arkko
	MMUSIC Working Group E. Carrara		MMUSIC Working Group E. Carrara
	INTERNET-DRAFT F. Lindholm		INTERNET-DRAFT F. Lindholm
	Expires: August 2003 M. Naslund		Expires: February 2004 M. Naslund
	K. Norrman		K. Norrman
	Ericsson		Ericsson
	February, 2003		August 2003
	Key Management Extensions for Session Description		Key Management Extensions for Session Description
	Protocol (SDP) and Real Time Streaming Protocol (RTSP)		Protocol (SDP) and Real Time Streaming Protocol (RTSP)
	<draft-ietf-mmusic-kmgmt-ext-07.txt>		<draft-ietf-mmusic-kmgmt-ext-08.txt>
	Status of this memo		Status of this memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that other		Task Force (IETF), its areas, and its working groups. Note that other
	groups may also distribute working documents as Internet-Drafts.		groups may also distribute working documents as Internet-Drafts.
	skipping to change at page 1, line 35		skipping to change at page 1, line 35
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or cite them other than as "work in progress".		material or cite them other than as "work in progress".
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/lid-abstracts.txt		http://www.ietf.org/ietf/lid-abstracts.txt
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html		http://www.ietf.org/shadow.html
			Copyright Notice
			Copyright (C) The Internet Society (2003). All Rights Reserved.
	Abstract		Abstract
	This document defines general extensions for SDP and RTSP to carry		This document defines general extensions for SDP and RTSP to carry
	the security information needed by a key management protocol, in		the security information needed by a key management protocol, in
	order to secure the media. These extensions are presented as a		order to secure the media. These extensions are presented as a
	framework, to be used by one or more key management protocols. As		framework, to be used by one or more key management protocols. As
	such, its use is meaningful only when it is completed by the key		such, its use is meaningful only when it is completed by the key
	management protocol in use.		management protocol in use.
	General guidelines are also given on how the framework should be used		General guidelines are also given on how the framework should be used
	together with SIP and RTSP.		together with SIP and RTSP.
	TABLE OF CONTENTS		TABLE OF CONTENTS
	1. Introduction.....................................................2		1. Introduction.....................................................2
	1.1. Notational Conventions.........................................3		1.1. Notational Conventions.........................................3
	2. Extensions to SDP and RTSP.......................................3		2. Extensions to SDP and RTSP.......................................4
	2.1. SDP Extensions.................................................4		2.1. SDP Extensions.................................................4
	2.2. RTSP Extensions................................................5		2.2. RTSP Extensions................................................4
	3. Usage with SIP and RTSP..........................................5		3. Usage with SIP and RTSP..........................................5
	3.1. General SDP processing.........................................5		3.1. General SDP processing.........................................5
	3.2. SIP usage......................................................7		3.2. SIP usage......................................................7
	3.3. RTSP usage.....................................................8		3.3. RTSP usage.....................................................8
	3.4. Example scenarios..............................................9		3.4. Example scenarios..............................................9
	4. Adding further Key management protocols.........................11		4. Adding further Key management protocols.........................11
	5. Security Considerations.........................................11		5. Security Considerations.........................................12
	6. IANA Considerations.............................................12		6. IANA Considerations.............................................13
	6.1. SDP Attribute Registration....................................12		6.1. SDP Attribute Registration....................................13
	6.2. Protocol Identifier Registration..............................13		6.2. Protocol Identifier Registration..............................13
	7. Conclusions.....................................................13		8. Acknowledgments.................................................14
	8. Acknowledgments.................................................13
	9. Author's Addresses..............................................14		9. Author's Addresses..............................................14
	10. References.....................................................14		10. References.....................................................15
	10.1. Normative References.........................................14		10.1. Normative References.........................................15
	10.2. Informative References.......................................15		10.2. Informative References.......................................15
	1. Introduction		1. Introduction
	[Editor remark] All instances of RFC xxxx should be replaced with		[Editor remark] All instances of RFC xxxx should be replaced with
	the RFC number of this document, when published. Furthermore, all		the RFC number of this document, when published. Furthermore, all
	instances of RFC yyyy should be replaced with the RFC number of		instances of RFC yyyy should be replaced with the RFC number of
	the MIKEY (Multimedia Internet KEYing) document [MIKEY], when		the MIKEY (Multimedia Internet KEYing) document [MIKEY], when
	published.		published.
	There has recently been work to define a security framework for the		There has recently been work to define a security framework for the
	protection of real-time applications running over RTP, [SRTP].		protection of real-time applications running over RTP, [SRTP].
	However, a security protocol needs a key management infrastructure to		However, a security protocol needs a key management infrastructure to
	exchange keys and security parameters, managing and refreshing keys,		exchange keys and security parameters, manage and refresh keys, etc.
	etc.
	A key management protocol is executed prior to the security protocol		A key management protocol is executed prior to the security protocol
	execution. The key management protocol's main goal is to, in a secure		execution. The key management protocol's main goal is to, in a secure
	and reliable way, establish a so-called security association for the		and reliable way, establish a security association for the security
	security protocol. This includes one or several cryptographic keys		protocol. This includes one or more cryptographic keys and the set of
	and a set of necessary parameters for the security protocol, e.g.,		necessary parameters for the security protocol, e.g., cipher and
	cipher and authentication algorithm to be used. The key management		authentication algorithm to be used. The key management protocol has
	protocol has similarities with, e.g., SIP [SIP] and RTSP [RTSP] in		similarities with, e.g., SIP [SIP] and RTSP [RTSP] in the sense that
	the sense that it negotiates necessary information in order to be		it negotiates necessary information in order to be able to setup the
	able to setup the session.		session.
	The focus in the following sections is to describe SDP attribute		The focus in the following sections is to describe a new SDP
	extensions and RTSP header extensions to support key management, and		attribute and RTSP header extension to support key management, and
	a possible integration within SIP and RTSP. A framework is therefore		the integration within SIP and RTSP. A framework is therefore
	described in the following. Such a framework will need to be		described in the following. This framework is completed by one or
	completed by one or more key management protocols, to describe how		more key management protocols, to describe how the framework is used,
	the framework is used, e.g. which is the data to be carried in the		e.g. which is the data to be carried in the extensions.
	extensions.
	Some of the motivations to create a framework with the possibility to		Some of the motivations to create a framework with the possibility to
	include the key management in the session establishment are:		include the key management in the session establishment are:
	* Just as the codec information is a description of how to encode and		* Just as the codec information is a description of how to encode and
	decode the audio (or video) stream, the key management data is a		decode the audio (or video) stream, the key management data is a
	description of how to encrypt and decrypt the data.		description of how to encrypt and decrypt the data.
	* The possibility to negotiate the security for the entire multimedia		* The possibility to negotiate the security for the entire multimedia
	session at the same time.		session at the same time.
	* The knowledge of the media at the session establishment makes it		* The knowledge of the media at the session establishment makes it
	easy to tie the key management to the multimedia sessions.		easy to tie the key management to the multimedia sessions.
	* This approach may be more efficient than setting up the security		* This approach may be more efficient than setting up the security
	later, as that approach might force extra roundtrips, possibly		later, as that approach might force extra roundtrips, possibly
	also a separate set-up for each stream, hence implying more delay		also a separate set-up for each stream, hence implying more delay
	to the actual setup of the media session.		to the actual setup of the media session.
			* The possibility to negotiate keying material end-to-end without
			applying end-to-end protection of the SDP (instead, hop-by-hop
			security mechanisms can be used which may be useful if
			intermediate proxies needs access to the SDP).
	Currently in SDP [SDPnew], one field exists to transport keys, i.e.		Currently in SDP [SDPnew], one field exists to transport keys, i.e.
	the "key=" field. However, this is not enough for a key management		the "k=" field. However, this is not enough for a key management
	protocol as there are many more parameters that need to be		protocol as there are many more parameters that need to be
	transported. The approach here is to use and extend the SDP		transported. The approach here is to use and extend the SDP
	description to transport the key management offer/answer and also to		description to transport the key management offer/answer and also to
	associate it with the media sessions. SIP uses the offer/answer model		associate it with the media sessions. SIP uses the offer/answer model
	[OAM] whereby extensions to SDP will be enough. However, RTSP [RTSP]		[OAM] whereby extensions to SDP will be enough. However, RTSP
	does not use the offer/answer model. This makes it impossible to send		[RTSP]does not use the offer/answer model with SDP, so a new header
	back an answer to the server. To solve this, a new header is		is introduced to convey key management data.
	introduced in which the key management data can be included.
	1.1. Notational Conventions		1.1. Notational Conventions
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC-2119.		document are to be interpreted as described in [RFC2119].
	2. Extensions to SDP and RTSP		2. Extensions to SDP and RTSP
	This section describes common attributes that are to be included in		This section describes common attributes that are to be included in
	an SDP description or in an RTSP header when an integrated key		an SDP description or in an RTSP header when an integrated key
	management protocol is used. The attribute values MUST follow the		management protocol is used. The attribute values MUST follow the
	general SDP or RTSP guidelines.		general SDP or RTSP guidelines (see [SDPnew] and [RTSP]).
	For the SDP description, the key management attributes MAY be defined
	at session level (i.e. before the media descriptor lines) and/or at
	media level. If the key management attributes are defined at media
	level, they will only apply to that specific media. If the key
	management attributes are defined at both session and media level,
	the media level definition overrides the session level definition for
	that specific media.
	The following SDP attribute is defined:
	key-mgmt:<identifier> <opaque-data>
	<identifier> is the name of the key management protocol and the		For both SDP and RTSP, the general method of adding the key
	opaque-data is a field to transport the key management protocol data.		management protocol is to introduce new attributes, one identifier to
	The key management protocol data contains the necessary information		identify the specific key management protocol, and one data field
	to establish the security protocol, e.g., keys and cryptographic		where the key management protocol data is placed. The key management
	parameters. All parameters and keys are protected by the key		protocol data contains the necessary information to establish the
	management. Note that if the key management protocol fails, e.g., the		security protocol, e.g., keys and cryptographic parameters. All
	receiver does not accept any of the proposed security parameters, or		parameters and keys are protected by the key management.
	simply does not understand the key management protocol, the security
	setup will fail. Consequently, it is impossible to establish a secure
	session. So, if the key management fails, the offer must be rejected.
	2.1. SDP Extensions		2.1. SDP Extensions
	This section provides an Augmented Backus-Naur Form (ABNF) grammar		This section provides an Augmented Backus-Naur Form (ABNF) grammar
	(as used in [SDPnew]) for the key management extensions to SDP.		(as used in [SDPnew]) for the key management extensions to SDP.
	Note that the new definitions are compliant with the definition of an		Note that the new definitions are compliant with the definition of an
	attribute field, i.e.		attribute field, i.e.
	attribute = (att-field ":" att-value) | att-field		attribute = (att-field ":" att-value) | att-field
	skipping to change at page 4, line 48		skipping to change at page 4, line 40
	One new attribute for SDP is defined:		One new attribute for SDP is defined:
	key-mgmt = "key-mgmt: " prtcl-id keymgmt-data		key-mgmt = "key-mgmt: " prtcl-id keymgmt-data
	prtcl-id = non-ws-string		prtcl-id = non-ws-string
	; e.g. "mikey"		; e.g. "mikey"
	keymgmt-data = text		keymgmt-data = text
	where non-ws-string and text are as defined in SDP [SDPnew]. The		where non-ws-string and text are as defined in SDP [SDPnew]. The
	attribute may be used at session level, media level or at both		attribute may be used at session level, media level, or at both
	levels. An attribute defined at media level overrides an attribute		levels. An attribute defined at media level overrides an attribute
	defined at session level. Note that the prtcl-id name will be case		defined at session level. Note that the prtcl-id name will be case
	sensitive and it is therefore RECOMMENDED that attributes registered		sensitive and it is therefore RECOMMENDED that attributes registered
	be in lower case letters.		are in lower case letters. Section 3 describes in detail how the
			attributes are used and how the SDP is handled in different usage
			scenarios.
	2.2. RTSP Extensions		2.2. RTSP Extensions
	To support the needed attribute described, the following RTSP header		To support the needed attribute, the following RTSP header is
	is defined:		defined:
	KeyMgmt = "keymgmt" ":" 1#key-mgmt-spec		KeyMgmt = "keymgmt" ":" 1#key-mgmt-spec
	key-mgmt-spec = "prot" "=" token ";" "data" "=" quoted-string		key-mgmt-spec = "prot" "=" token ";" "data" "=" quoted-string
			"token" and "quoted-string" are as defined in the RTSP specification
	token and quoted-string are as defined in the RTSP specification
	[RTSP].		[RTSP].
	The KeyMgmt header should be possible to use in the messages		The KeyMgmt header should be possible to use in the messages
	described in the table below.		described in the table below.
	Method Direction Requirement		Method Direction Requirement
	DESCRIBE C->S required		DESCRIBE C->S required
	SETUP C->S required		SETUP C->S required
	ANNOUNCE C->S, S->C optional (required: if re-key should		ANNOUNCE C->S, S->C optional (required: if re-key is supported)
	be supported)
			Note: Section 3 describes in detail how the RTSP extensions are used.
	3. Usage with SIP and RTSP		3. Usage with SIP and RTSP
	This section gives recommendations of how/when to include the defined		This section gives recommendations of how/when to include the defined
	key management attribute when SIP and/or RTSP are used together with		key management attribute when SIP and/or RTSP are used together with
	SDP.		SDP.
	When a key management protocol is integrated with SIP/SDP and RTSP,		When a key management protocol is integrated with SIP/SDP and RTSP,
	the following requirements are put on the key management:		the following requirements are placed on the key management:
	* It MUST be possible to execute the key management protocol in at		* It MUST be possible to execute the key management protocol in at
	most one roundtrip in case the answerer accepts the offer.		most one roundtrip in case the answerer accepts the offer.
	* It MUST be possible from the SIP/SDP and RTSP application, using		* It MUST be possible from the SIP/SDP and RTSP application, using
	the key management API, to receive key management data, and		the key management API, to receive key management data, and
	information of whether a message is accepted or not.		information of whether a message is accepted or not.
	Today, the MIKEY protocol [MIKEY] has adopted the key management		Today, the MIKEY protocol [MIKEY] has adopted the key management
	extensions to work together with SIP and RTSP. Other protocols MAY		extensions to work together with SIP and RTSP. Other protocols MAY
	use the described attribute and header, e.g. Kerberos [KERB].		use the described attribute and header, e.g. Kerberos [KERB].
	3.1. General SDP processing		3.1. General SDP processing
	When an SDP message is created, the following procedure should be		When an SDP message is created, the following procedure should be
	applied:		applied:
	* The identifier of the key management protocol used (e.g. MIKEY or		* The identifier of the key management protocol used (e.g. MIKEY or
	Kerberos) MUST be put in the prtcl-id field.		Kerberos) MUST be placed in the prtcl-id field.
	* The keymgmt-data field MUST be created as follows. The key		* The keymgmt-data field MUST be created as follows. The key
	management protocol MUST be used to create the key management		management protocol MUST be used to create the key management
	message. This message SHALL be base64 encoded by SDP and then		message. This message SHALL be base64 encoded [RFC3548] by the SDP
	encapsulated in the keymgmt-data attribute. The data may e.g. be a		application and then encapsulated in the keymgmt-data attribute.
	MIKEY message (see [MIKEY], Section 7) or Kerberos ticket.		The data may e.g. be a MIKEY message (see [MIKEY], Section 7) or
			Kerberos ticket.
	A received SDP message that contains the key management attributes		A received SDP message that contains the key management attributes
	SHOULD process these attributes in the following manner:		SHOULD be processed in the following manner:
	* The key management protocol used MUST be identified by checking the		* The key management protocol is identified according to the prtcl-id
	prtcl-id field in the key management attribute.		field.
	* The key management data from the keymgmt-data field MUST be		* The key management data from the keymgmt-data field MUST be
	extracted, base64 decoded to reconstruct the original message, and		extracted, base64 decoded to reconstruct the original message, and
	then passed to the key management protocol for further processing.		then passed to the key management protocol. Note that depending on
	Note that depending on key management protocol, some extra		key management protocol, some extra parameters might of course be
	parameters might of course be requested by the API, such as the		requested by the specific API, such as the source/destination
	source/destination network address/port(s) for the specified media		network address/port(s) for the specified media (however, this
	(however, the key management interface specification should		will be implementation specific depending on the actual API).
	specify this).
	* Depending on the outcome of the key management processing (i.e.		* Depending on the outcome of the key management processing (i.e.
	whether it was accepted or not), the processing can proceed		whether it was successful or not), the processing can proceed
	according to normal processing (e.g. according to the offer/answer		according to normal rules (e.g. according to the offer/answer
	model, see also Section 3.2).		model, see also Section 3.2).
	Note that the attribute MAY be repeated more than once (e.g., one at		Note that the key management attribute MAY be repeated more than once
	session level and one at media level). Consequently, the process is		(e.g., one at session level and one at media level). Consequently,
	repeated for each key management attribute detected.		the process is repeated for each key management attribute detected.
			However, in case of failure of the key management (on either session
			or media level), the session setup SHALL be aborted (see also Section
			3.2 and Section 3.3 for more details).
	If more than one key management protocol is supported, multiple		If more than one key management protocol is supported, multiple
	instances of the key management attribute MAY be included in the		instances of the key management attribute MAY be included in the
	initial offer, each transporting a different key management data,		initial offer, each transporting a different key management data,
	thus indicating alternatives supported.		thus indicating supported alternatives.
	If the sender includes more than one key management protocol		If the sender includes more than one key management protocol
	attributes at session level (analogous for the media level), these		attribute at session level (analogous for the media level), these
	SHOULD be listed in order of preference (with the first being the		SHOULD be listed in order of preference (the first being the
	preferred). The receiver chooses the key management protocol it		preferred). The receiver selects the key management protocol it
	supports. When answering, only the accepted key management protocol		wishes to use and includes only that attribute in the answer. If the
	attribute MUST be included. If the receiver does not support any of		receiver does not support any of the sender's suggested key
	the sender's suggested key management protocols, the receiver answers		management protocols, the receiver returns an error message (see
	with an error message (see SIP and RTSP), whereby the sender MUST put		section 3.2 and section 3.3), whereby the sender MUST abort the
	down the current setup procedure.		current setup procedure.
	Note that the placement of multiple key management offers in a single		Note that the placement of multiple key management offers in a single
	message has the disadvantage that the message expands and the		message has the disadvantage that the message expands and the
	computational workload for the offerer will increase drastically. The		computational workload for the offerer will increase drastically.
	possibility to support multiple key management protocols may
			The possibility to support multiple key management protocols may
	introduce bidding down attacks. To avoid this, the list of		introduce bidding down attacks. To avoid this, the list of
	identifiers of the proposed key management protocols MUST be		identifiers of the proposed key management protocols MUST be
	authenticated, which MUST be done by each key management.		authenticated. The authentication MUST be done separately by each key
			management protocol (see e.g. Section 7.1 in [MIKEY]).
	This puts the requirement that it MUST be specified (in the key		Accordingly, it MUST be specified (in the key management protocol
	management protocol itself or in a companion document) how the		specification itself or in a companion document) how the list of key
	protocol identifiers could be authenticated from the offerer to the		management protocol identifiers can be authenticated from the offerer
	responder by the use of the specific key management protocol. Note		to the answerer by the specific key management protocol. Note that
	that even if only one key management protocol is used, that still		even if only one key management protocol is used, that still MUST
	must authenticate its own protocol identifier. If the key management		authenticate its own protocol identifier.
	protocol fails to authenticate the protocol list, it MUST return an
	error message to SDP.
	The list of protocol identifiers MUST be given to the selected key		The list of protocol identifiers MUST be given to the selected key
	management protocol by SDP with ";" separated identifiers. All the		management protocol by the SDP application with ";" separated
	offered protocol identifiers MUST be included, in the same order as		identifiers. All the offered protocol identifiers MUST be included,
	they appear in the corresponding SDP description.		in the same order as they appear in the corresponding SDP
			description.
	The protocol list can formally be described as		The protocol list can formally be described as
	prtcl-list = prtcl-id *(";" prtcl-id)		prtcl-list = prtcl-id *(";" prtcl-id)
	prtcl-id = non-ws-string		prtcl-id = non-ws-string
	Example		For example, if the SDP is:
	v=0		v=0
	o=alice 2891092738 2891092738 IN IP4 lost.downunder.dom		o=alice 2891092738 2891092738 IN IP4 lost.example.com
	s=Secret discussion		s=Secret discussion
	t=0 0		t=0 0
	c=IN IP4 lost.downunder.dom		c=IN IP4 lost.example.com
	a=key-mgmt:mikey <data1>		a=key-mgmt:mikey <data1>
	a=key-mgmt:keyp1 <data2>		a=key-mgmt:keyp1 <data2>
	a=key-mgmt:keyp2 <data3>		a=key-mgmt:keyp2 <data3>
	m=audio 39000 RTP/SAVP 98		m=audio 39000 RTP/SAVP 98
	a=rtpmap:98 AMR/8000		a=rtpmap:98 AMR/8000
	m=video 42000 RTP/SAVP 31		m=video 42000 RTP/SAVP 31
	a=rtpmap:31 H261/90000		a=rtpmap:31 H261/90000
	The protocol list, "mikey;keyp1;keyp2", would be generated from		The protocol list, "mikey;keyp1;keyp2", would be generated from
	the SDP description and used as input to the selected key		the SDP description and used as input to each specified key
	management protocol (together with the data for that protocol).		management protocol (together with the data for that protocol).
	If more than one protocol is supported by the offerer, it is		If more than one protocol is supported by the offerer, it is
	RECOMMENDED that he offers all to him acceptable protocols in the		RECOMMENDED that all acceptable protocols are included in the first
	first offer, rather than making single, subsequent alternative offers		offer, rather than making single, subsequent alternative offers in
	in response to error messages, see "Security Considerations".		response to error messages, see "Security Considerations".
	3.2. SIP usage		3.2. SIP usage
	The offerer SHOULD include the key management data within an offer		When used with SIP and the offer/answer model, the offerer SHOULD
	that contains the media description it should apply to. The answerer		include the key management data within an offer that contains the
	MUST check with the key management protocol if the attribute values		media description it should apply to. The answerer MUST check with
	are valid, and then obtain from the key management the data to		the key management protocol if the attribute values are valid, and
	include in the answer.		then obtain from the key management the data to include in the
			answer.
	If the offer is not accepted, the answerer SHOULD return a "606 Not		If the offer is not accepted, the answerer SHOULD return a "606 Not
	Acceptable" message, including one or more Warning headers (at least		Acceptable" message, including one or more Warning headers (at least
	a 306). The offer MUST then abort the security setup.		a 306 "Attribute not understood"). The session is then aborted (and
			it is up to local policy or end user to decide how to continue).
	Re-keying can be handled as a new offer, i.e. a re-INVITE should be		Re-keying can be handled as a new offer, i.e. a re-INVITE should be
	sent with the new proposed parameters. The answerer treats this as a		sent with the new proposed parameters. The answerer treats this as a
	new offer where the key management is the issue of change. In		new offer where the key management is the issue of change. In
	general, the re-INVITE (and the key exchange) must be finalized		general, the re-INVITE (and the key exchange) must be finalized
	before the security protocol can change the keys. The synchronization		before the security protocol can change the keys. The same key
	method used when changing keys are dependent on the security and key		management protocol used in the original INVITE SHALL also be used in
	management protocol used. The same protocol used in the original		the re-INVITE carrying re-keying. If the re-INVITE carrying re-keying
	INVITE SHALL also be used in the re-INVITE carrying re-keying. If the		fails (e.g., the authentication verification fails), the answerer
	re-INVITE carrying re-keying fails (e.g., the authentication		SHOULD send a "606 Not Acceptable" message, including one or more
	verification fails), the answerer SHOULD send a "606 Not Acceptable"		Warning headers (at least a 306). The offer MUST then abort the
	message, including one or more Warning headers (at least a 306). The		security setup.
	offer MUST then abort the security setup.
	3.3. RTSP usage		3.3. RTSP usage
	RTSP does not use the offer/answer model, as SIP does. This causes		RTSP does not use the offer/answer model, as SIP does. This causes
	some problems, as it is not possible (without abusing RTSP) to send		some problems, as it is not possible (without abusing RTSP) to send
	back an answer to the server (as the server will in most cases be the		back an answer to the server (as the server will in most cases be the
	one initiating the security parameter exchange). To solve this, a new		one initiating the security parameter exchange). To solve this, a new
	header has been introduced (Section 2.2). This also assumes that the		header has been introduced (Section 2.2). This also assumes that the
	key management also has some kind of binding to the media, so that		key management also has some kind of binding to the media, so that
	the response to the server will be processed as required.		the response to the server will be processed as required.
	The processing of a key management header in RTSP should be done		The initial key management message from a server should be sent to
	analogous of the SDP message processing. The initial key management		the client using SDP. When responding to this, the client uses the
	message from a server should be sent to the client using SDP. When		new RTSP header to send back an answer (included in the SETUP
	responding to this, the client uses the new RTSP header to send back		message). If a server receives a SETUP message in which it expects a
	an answer (included in the SETUP message). If a server receives a		key management message, but none is included, a 403 Forbidden SHOULD
	SETUP message in which it expects a key management message, but none		be returned to the client, whereby the current setup MUST be aborted.
	is included, a 403 Forbidden SHOULD be returned to the client,
	whereby the current setup MUST be aborted.		The processing of creating a key management header in RTSP SHOULD be
			as follow:
			* The identifier of the key management protocol used (e.g. MIKEY or
			Kerberos) MUST be placed in the "prot" field of the header.
			* The keymgmt-data field MUST be created as follows. The key
			management protocol MUST be used to create the key management
			message. This message SHALL be base64 encoded by the SDP
			application and then encapsulated in the "data" field of the
			header. The data may e.g. be a MIKEY message (see [MIKEY], Section
			7) or Kerberos ticket.
			A received key management header SHOULD be processed in the following
			manner:
			* The key management protocol is identified according to the "prot"
			field.
			* The key management data from the "data" field MUST be extracted,
			base64 decoded to reconstruct the original message, and then
			passed to the key management protocol. Note that depending on the
			key management protocol, some extra parameters might of course be
			requested by the specific API, such as the source/destination
			network address/port(s) for the specified media (however, this
			will be implementation specific depending on the actual API).
			* Depending on the outcome of the key management processing (i.e.
			whether it was successful or not), the processing can proceed
			according to normal rules (see also below).
	The server MAY provide re-keying/updating facilities by sending a new		The server MAY provide re-keying/updating facilities by sending a new
	key management message in an ANNOUNCE messages. The ANNOUNCE message		key management message in an ANNOUNCE messages. The ANNOUNCE message
	contains an SDP message including the key management parameters. The		contains an SDP message including the key management parameters. The
	response message is put in the new RTSP header in the response from		response message is put in the new RTSP header in the response from
	the client to the server. Note that the ANNOUNCE messages MUST be		the client to the server. Note that the ANNOUNCE messages MUST be
	supported if this feature is to be used.		supported if this feature is to be used.
	3.4. Example scenarios		3.4. Example scenarios
	Example 1 (SIP)		Example 1 (SIP)
	A SIP call is taking place between Alice and Bob. Alice sends an		A SIP call is taking place between Alice and Bob. Alice sends an
	Invite message consisting of the following offer:		Invite message consisting of the following offer:
	v=0		v=0
	o=alice 2891092738 2891092738 IN IP4 lost.somewhere.com		o=alice 2891092738 2891092738 IN IP4 w-land.example.com
	s=Cool stuff		s=Cool stuff
	e=alice@w-land.org		e=alice@w-land.example.com
	t=0 0		t=0 0
	c=IN IP4 lost.somewhere.com		c=IN IP4 w-land.example.com
	a=key-mgmt:mikey uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...		a=key-mgmt:mikey uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...
	m=audio 49000 RTP/SAVP 98		m=audio 49000 RTP/SAVP 98
	a=rtpmap:98 AMR/8000		a=rtpmap:98 AMR/8000
	m=video 52230 RTP/SAVP 31		m=video 52230 RTP/SAVP 31
	a=rtpmap:31 H261/90000		a=rtpmap:31 H261/90000
	i.e. Alice proposes to set up one audio stream and one video stream		i.e. Alice proposes to set up one audio stream and one video stream
	that run over SRTP. To set up the security parameters for SRTP, she		that run over SRTP. To set up the security parameters for SRTP, she
	uses MIKEY. Note that MIKEY is negotiating the crypto suite for both		uses MIKEY. Note that MIKEY is negotiating the crypto suite for both
	streams (as it is placed at the session level).		streams (as it is placed at the session level).
	Bob accepts the offer and sends an answer back to Alice:		Bob accepts the offer and sends an answer back to Alice:
	v=0		v=0
	o=bob 2891092897 2891092897 IN IP4 found.somewhere.com		o=bob 2891092897 2891092897 IN IP4 foo.example.com
	s=Cool stuff		s=Cool stuff
	e=bob@null.org		e=bob@foo.example.com
	t=0 0		t=0 0
	c=IN IP4 found.somewhere.com		c=IN IP4 foo.example.com
	a=key-mgmt:mikey skaoqDeMkdwRW278HjKVB...		a=key-mgmt:mikey skaoqDeMkdwRW278HjKVB...
	m=audio 49030 RTP/SAVP 98		m=audio 49030 RTP/SAVP 98
	a=rtpmap:98 AMR/8000		a=rtpmap:98 AMR/8000
	m=video 52230 RTP/SAVP 31		m=video 52230 RTP/SAVP 31
	a=rtpmap:31 H261/90000		a=rtpmap:31 H261/90000
	Example 2 (SDP)		Example 2 (SDP)
	This example shows how Alice would have done in the previous example		This example shows how Alice would have done if she wished to protect
	if she wished to protect only the audio stream.		only the audio stream.
	v=0		v=0
	o=alice 2891092738 2891092738 IN IP4 lost.somewhere.com		o=alice 2891092738 2891092738 IN IP4 w-land.example.com
	s=Cool stuff		s=Cool stuff
	e=alice@w-land.org		e=alice@w-land.example.com
	t=0 0		t=0 0
	c=IN IP4 lost.somewhere.com		c=IN IP4 w-land.example.com
	m=audio 49000 RTP/SAVP 98		m=audio 49000 RTP/SAVP 98
	a=rtpmap:98 AMR/8000		a=rtpmap:98 AMR/8000
	a=key-mgmt:mikey uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...		a=key-mgmt:mikey uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...
	m=video 52230 RTP/AVP 31		m=video 52230 RTP/AVP 31
	a=rtpmap:31 H261/90000		a=rtpmap:31 H261/90000
	Note that even if the key management attribute is specified at		Note that even if the key management attribute were specified at
	session level, the video part will not be affected by this (as a		session level, the video part would not be affected by this (as a
	security profile is not used).		security profile is not used).
	Example 3 (RTSP)		Example 3 (RTSP)
	A client wants to set up a streaming session and requests a media		A client wants to set up a streaming session and requests a media
	description from the streaming server.		description from the streaming server.
	DESCRIBE rtsp://server.example.com/fizzle/foo RTSP/1.0		DESCRIBE rtsp://server.example.com/fizzle/foo RTSP/1.0
	CSeq: 312		CSeq: 312
	Accept: application/sdp		Accept: application/sdp
	From: user@client.com		From: user@example.com
	The server sends back an OK message including an SDP description.		The server sends back an OK message including an SDP description.
	RTSP/1.0 200 OK		RTSP/1.0 200 OK
	CSeq: 312		CSeq: 312
	Date: 23 Jan 1997 15:35:06 GMT		Date: 23 Jan 1997 15:35:06 GMT
	Content-Type: application/sdp		Content-Type: application/sdp
	v=0		v=0
	o=actionmovie 2891092738 2891092738 IN IP4 movie.somewhere.com		o=actionmovie 2891092738 2891092738 IN IP4 movie.example.com
	s=Action Movie		s=Action Movie
	e=action@movie.somewhere.com		e=action@movie.example.com
	t=0 0		t=0 0
	c=IN IP4 movie.somewhere.com		c=IN IP4 movie.example.com
	a=key-mgmt:mikey uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...		a=key-mgmt:mikey uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...
	m=audio 0 RTP/SAVP 98		m=audio 0 RTP/SAVP 98
	a=rtpmap:98 AMR/8000		a=rtpmap:98 AMR/8000
	control:rtsp://movie.somewhere.com/action/audio		control:rtsp://movie.example.com/action/audio
	m=video 0 RTP/SAVP 31		m=video 0 RTP/SAVP 31
	a=rtpmap:31 H261/90000		a=rtpmap:31 H261/90000
	control:rtsp://movie.somewhere.com/action/video		control:rtsp://movie.example.com/action/video
	The client is now ready to setup the sessions. It includes the key		The client is now ready to setup the sessions. It includes the key
	management data in the first message going back to the server (i.e.		management data in the first message going back to the server (i.e.
	the SETUP message).		the SETUP message).
	SETUP rtsp://movie.somewhere.com/action/audio RTSP/1.0		SETUP rtsp://movie.example.com/action/audio RTSP/1.0
	CSeq: 313		CSeq: 313
	Transport: RTP/SAVP/UDP;unicast;client_port=3056-3057		Transport: RTP/SAVP/UDP;unicast;client_port=3056-3057
	keymgmt: prot=mikey; data="skaoqDeMkdwRW278HjKVB..."		keymgmt: prot=mikey; data="skaoqDeMkdwRW278HjKVB..."
	The server processes the request including checking the validity of		The server processes the request including checking the validity of
	the key management header.		the key management header.
	RTSP/1.0 200 OK		RTSP/1.0 200 OK
	CSeq: 313		CSeq: 313
	Session: 12345678		Session: 12345678
	Transport: RTP/SAVP/UDP;unicast;client_port=3056-3057;		Transport: RTP/SAVP/UDP;unicast;client_port=3056-3057;
	server_port=5000-5001		server_port=5000-5001
	The RTSP then proceeds as usual (with e.g. a SETUP message for the		The RTSP then proceeds as usual (with e.g. a SETUP message for the
	skipping to change at page 11, line 43		skipping to change at page 12, line 17
	included in the offer in the correct order as they appear.		included in the offer in the correct order as they appear.
	The key management data MUST be base64 encoded in the SDP and RTSP		The key management data MUST be base64 encoded in the SDP and RTSP
	fields. Therefore, considerations of possible conversion from the		fields. Therefore, considerations of possible conversion from the
	normal key management representation to base64 SHOULD be taken into		normal key management representation to base64 SHOULD be taken into
	account.		account.
	5. Security Considerations		5. Security Considerations
	The nature of this document is to allow SDP and RTSP to support		The nature of this document is to allow SDP and RTSP to support
	security of the media sessions. It is therefore not a primary		negotiation of the security of the media sessions. It is therefore
	intention of this document to describe possible security solutions or		not a primary intention of this document to describe possible
	to define possible security problems. The defined SDP and RTSP		security solutions or to define possible security problems. The
	extensions are not believed to introduce any new security risks to		defined SDP and RTSP extensions are not believed to introduce any new
	SDP and RTSP, if used as specified.		security risks to SDP and RTSP, if used as specified.
	Note that the purpose of the key management fields is to provide		Note that the purpose of the key management fields is to provide
	information to secure the media streams. Under the assumption that		information to secure the media streams. Under the assumption that
	the key management schemes are secure, the SDP can be passed along		the key management schemes are secure, the SDP can be passed along
	unprotected without affecting the key management, and the media		unprotected without affecting the key management, and the media
	streams will still be secure even if some attackers gained knowledge		streams will still be secure even if some attackers gained knowledge
	of the SDP contents.		of the SDP contents.
	However, if the SDP messages are not sent authenticated between the		However, if the SDP messages are not sent authenticated between the
	parties, it is possible for an active attacker to change attributes		parties, it is possible for an active attacker to change attributes
	without being detected. As the key management protocol may		without being detected. As the key management protocol may
	(indirectly) rely on some of the session information from SDP (e.g.,		(indirectly) rely on some of the session information from SDP (e.g.,
	address information), an attack on SDP may have indirect consequences		address information), an attack on SDP may have indirect consequences
	on the key management. Even if the key management protocol does not		on the key management. Even if the key management protocol does not
	rely on parameters of SDP and will not be affected by manipulation of		rely on parameters of SDP and will not be affected by manipulation of
	these, different DoS attacks aimed at SDP (e.g. the SIMCAP		these, different DoS attacks aimed at SDP (e.g. the SIMCAP
	extensions) may lead to undesired interruption in the setup. In		extensions) may lead to undesired interruption in the setup.
	general, it is therefore a good thing, not only to try to secure the
	session, but also to secure the session setup. However, a solution		In general, it is therefore a good thing, not only to try to secure
	for this might not necessarily need to be end-to-end, but could also		the session, but also to secure the session setup. However, the
	be hop-by-hop depending on the trust model for the specific use case.		security of the session setup might not possible on an end-to-end
			basis, but may require to be protected on a hop-by-hop basis (this is
			generally the case for SIP/SDP when intermediate proxies needs to
			obtain information about the sessions etc). In fact, the focus of
			this framework is mainly when end-to-end protection of the session
			setup is not used, but where the media streams needs to be end-to-end
			protected.
	Note that it is impossible to assure the authenticity of a declined		Note that it is impossible to assure the authenticity of a declined
	offer, since even if it comes from the true respondent, the fact that		offer, since even if it comes from the true respondent, the fact that
	the answerer declines the offer usually means that he does not		the answerer declines the offer usually means that he does not
	support the protocol(s) offered, and consequently cannot be expected		support the protocol(s) offered, and consequently cannot be expected
	to authenticate the response either. This means that if the initiator		to authenticate the response either. This means that if the initiator
	is unsure of which protocol(s) the responder supports, we RECOMMEND		is unsure of which protocol(s) the responder supports, we RECOMMEND
	that the initiator offers all acceptable protocols in a single offer.		that the initiator offers all acceptable protocols in a single offer.
	If not, this opens up the possibility for a "man-in-the-middle"		If not, this opens up the possibility for a "man-in-the-middle"
	(MITM) to affect the outcome of the eventually agreed upon protocol,		(MITM) to affect the outcome of the eventually agreed upon protocol,
	by faking unauthenticated error messages until the initiator		by faking unauthenticated error messages until the initiator
	eventually offers a protocol "to the liking" of the MITM. This is not		eventually offers a protocol "to the liking" of the MITM. This is not
	really a security problem, but rather a mild form of denial of		really a security problem, but rather a mild form of denial of
	service that can be avoided by following the above recommendation.		service that can be avoided by following the above recommendation.
	6. IANA Considerations		6. IANA Considerations
	6.1. SDP Attribute Registration		6.1. SDP Attribute Registration
	A new SDP attribute needs to be defined for the purpose of key		A new SDP attribute needs to be registered for the purpose of key
	management protocol integration with SDP.		management protocol integration with SDP.
	Contact: Fredrik Lindholm		Contact: Fredrik Lindholm
	mailto: fredrik.lindholm@era.ericsson.se		mailto: fredrik.lindholm@ericsson.com
	tel: +46 8 58531705		tel: +46 8 58531705
	SDP Attribute ("att-field"):		SDP Attribute ("att-field"):
	Name: key-mgmt		Name: key-mgmt
	Long form: key management protocol		Long form: key management protocol
	Type of name: att-field		Type of name: att-field
	Type of attribute: Media and session level		Type of attribute: Media and session level
	Purpose: See RFC xxxx, Section 2.		Purpose: See RFC xxxx, Section 2.
	Reference: RFC xxxx, Section 2.1		Reference: RFC xxxx, Section 2.1
	Values: See registrations below		Values: See registrations below
	6.2. Protocol Identifier Registration		6.2. Protocol Identifier Registration
	This document defines one new name space associated with the above		This document defines one new name space associated with the above
	registered key-mgmt attribute i.e., the protocol identifier (see also		registered key-mgmt attribute i.e., the protocol identifier (see also
	Section 2.1 and Section 2.2).		Section 2.1 and Section 2.2).
	A new registry needs to be set up for "prtcl-id" parameter of the		A new registry needs to be set up for "prtcl-id" parameter of the
	skipping to change at page 13, line 19		skipping to change at page 13, line 46
	This document defines one new name space associated with the above		This document defines one new name space associated with the above
	registered key-mgmt attribute i.e., the protocol identifier (see also		registered key-mgmt attribute i.e., the protocol identifier (see also
	Section 2.1 and Section 2.2).		Section 2.1 and Section 2.2).
	A new registry needs to be set up for "prtcl-id" parameter of the		A new registry needs to be set up for "prtcl-id" parameter of the
	"key-mgmt" attribute, with the following registration created		"key-mgmt" attribute, with the following registration created
	initially: "mikey".		initially: "mikey".
	Contact: Fredrik Lindholm		Contact: Fredrik Lindholm
	mailto: fredrik.lindholm@era.ericsson.se		mailto: fredrik.lindholm@ericsson.com
	tel: +46 8 58531705		tel: +46 8 58531705
	Value name: mikey		Value name: mikey
	Long name: Multimedia Internet KEYing		Long name: Multimedia Internet KEYing
	Purpose: Usage of MIKEY with the key-mgmt attribute		Purpose: Usage of MIKEY with the key-mgmt attribute
	Reference: Section 7 in RFC yyyy		Reference: Section 7 in RFC yyyy
	Further entries may be registered according to the "Specification		Further entries may be registered according to the "Specification
	Required" policy as defined in RFC 2434 [GWISC]. Each new		Required" policy as defined in [RFC2434]. Each new registration needs
	registration needs to indicate the parameter name and the syntax of		to indicate the parameter name and the syntax of possible additional
	possible additional arguments. Note that the parameter name is case		arguments. Note that the parameter name is case sensitive and it is
	sensitive and it is recommended that the name should be in lower case		recommended that the name should be in lower case letters. For each
	letters. For each new registration, it is mandatory that a permanent,		new registration, it is mandatory that a permanent, stable, and
	stable, and publicly accessible document exists that specifies the		publicly accessible document exists that specifies the semantics of
	semantics of the registered parameter, the syntax and semantics of		the registered parameter, the syntax and semantics of its parameters
	its parameters as well as all the requested details of interaction		as well as all the requested details of interaction between the key
	between the key management protocol and SDP, as specified in this		management protocol and SDP, as specified in this document.
	document.
	7. Conclusions
	A security solution for real-time applications needs a key management
	infrastructure. Integrating the key management scheme with the
	session establishment protocol could be done efficiently in most of
	the scenarios. This draft proposes a framework that integrates a key
	management protocol (e.g., MIKEY) into SIP and RTSP, and which can be
	accompanied by different key management protocols. A set of new
	attributes and headers has been defined in SDP and RTSP to support
	this.
	8. Acknowledgments		8. Acknowledgments
	Thanks to: Rolf Blom, Magnus Westerlund, and the rest involved in the		Thanks to: Rolf Blom, Magnus Westerlund, and the rest involved in the
	MMUSIC WG and the MSEC WG.		MMUSIC WG and the MSEC WG.
	A special thanks to Joerg Ott and Colin Perkins.		A special thanks to Joerg Ott and Colin Perkins.
	9. Author's Addresses		9. Author's Addresses
	Jari Arkko		Jari Arkko
	Ericsson		Ericsson
	02420 Jorvas Phone: +358 40 5079256		02420 Jorvas Phone: +358 40 5079256
	Finland Email: jari.arkko@ericsson.com		Finland Email: jari.arkko@ericsson.com
	Elisabetta Carrara		Elisabetta Carrara
	Ericsson Research		Ericsson Research
	SE-16480 Stockholm Phone: +46 8 50877040		SE-16480 Stockholm Phone: +46 8 50877040
	Sweden EMail: elisabetta.carrara@era.ericsson.se		Sweden EMail: elisabetta.carrara@ericsson.com
	Fredrik Lindholm		Fredrik Lindholm
	Ericsson Research		Ericsson Research
	SE-16480 Stockholm Phone: +46 8 58531705		SE-16480 Stockholm Phone: +46 8 58531705
	Sweden EMail: fredrik.lindholm@era.ericsson.se		Sweden EMail: fredrik.lindholm@ericsson.com
	Mats Naslund		Mats Naslund
	Ericsson Research		Ericsson Research
	SE-16480 Stockholm Phone: +46 8 58533739		SE-16480 Stockholm Phone: +46 8 58533739
	Sweden EMail: mats.naslund@era.ericsson.se		Sweden EMail: mats.naslund@ericsson.com
	Karl Norrman		Karl Norrman
	Ericsson Research		Ericsson Research
	SE-16480 Stockholm Phone: +46 8 4044502		SE-16480 Stockholm Phone: +46 8 4044502
	Sweden EMail: karl.norrman@era.ericsson.se		Sweden EMail: karl.norrman@ericsson.com
	10. References		10. References
	10.1. Normative References		10.1. Normative References
	[OAM] Rosenberg, J. and Schulzrinne, H., "An Offer/Answer Model with		[OAM] Rosenberg, J. and Schulzrinne, H., "An Offer/Answer Model with
	the Session Description Protocol (SDP)", IETF, 3264.		the Session Description Protocol (SDP)", IETF, RFC 3264.
	[RTSP] Schulzrinne, H., Rao, A., and Lanphier, R., "Real Time		[RTSP] Schulzrinne, H., Rao, A., and Lanphier, R., "Real Time
	Streaming Protocol (RTSP)", IETF, RFC 2326.		Streaming Protocol (RTSP)", IETF, RFC 2326.
			[RFC2119] Bradner, S. "Key words for use in RFCs to Indicate
			Requirement Levels", IETF, RFC 2119.
	[SDPnew] Handley, M., Jacobson, V., and Perkins, C., "SDP: Session		[SDPnew] Handley, M., Jacobson, V., and Perkins, C., "SDP: Session
	Description Protocol", Internet Draft, IETF, Work in progress		Description Protocol", Internet Draft, IETF, Work in progress
	(MMUSIC).		(MMUSIC), draft-ietf-mmusic-sdp-new-13.txt.
	[SIP] Handley, M., Schulzrinne, H., Schooler, E., and Rosenberg, J.,		[SIP] Handley, M., Schulzrinne, H., Schooler, E., and Rosenberg, J.,
	"SIP: Session Initiation Protocol", IETF, RFC 2543.		"SIP: Session Initiation Protocol", IETF, RFC 3261.
	[GWISC] Narten, T. and Alvestrand, H., "Guidelines for Writing an		[RFC2434] Narten, T. and Alvestrand, H., "Guidelines for Writing an
	IANA Considerations Section in RFCs", IETF, RFC 2434.		IANA Considerations Section in RFCs", IETF, RFC 2434.
			[RFC3548] Josefsson, S., "The Base16, Base32, and Base64 Data
			Encodings", IETF, RFC 3548.
	10.2. Informative References		10.2. Informative References
	[KERB] Kohl, J., Neuman, C., "The Kerberos Network Authentication		[KERB] Kohl, J., Neuman, C., "The Kerberos Network Authentication
	Service (V5)", IETF, RFC 1510.		Service (V5)", IETF, RFC 1510.
	[MIKEY] Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and		[MIKEY] Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and
	Norrman, K., "MIKEY: Multimedia Internet KEYing", IETF, RFC yyyy,		Norrman, K., "MIKEY: Multimedia Internet KEYing", IETF, RFC yyyy,
	[Internet Draft, Work in progress (MSEC)].		[Internet Draft, Work in progress (MSEC)].
	[SRTP] Baugher, M., Blom, R., Carrara, E., McGrew, D., Naslund, M,		[SRTP] Baugher, M., Blom, R., Carrara, E., McGrew, D., Naslund, M,
	Norrman, K., and Oran, D., "The Secure Real Time Transport Protocol",		Norrman, K., and Oran, D., "The Secure Real Time Transport Protocol",
	Internet Draft, IETF, Work in Progress (AVT).		Internet Draft, IETF, Work in Progress (AVT).
	This Internet-Draft expires in August 2003.		Copyright Notice
			Copyright (C) The Internet Society (2003). All Rights Reserved.
			This document and translations of it may be copied and furnished to
			others, and derivative works that comment on or otherwise explain it
			or assist in its implementation may be prepared, copied, published
			and distributed, in whole or in part, without restriction of any
			kind, provided that the above copyright notice and this paragraph are
			included on all such copies and derivative works. However, this
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			the copyright notice or references to the Internet Society or other
			Internet organizations, except as needed for the purpose of
			developing Internet standards in which case the procedures for
			copyrights defined in the Internet Standards process must be
			followed, or as required to translate it into languages other than
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			The limited permissions granted above are perpetual and will not be
			revoked by the Internet Society or its successors or assigns.
			This document and the information contained herein is provided on an
			"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
			TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
			BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
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			This Internet-Draft expires in February 2004.
End of changes.
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