draft-ietf-mmusic-kmgmt-ext-11.txt		draft-ietf-mmusic-kmgmt-ext-12.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: October 2004 M. Naslund		Expires: April 2005 M. Naslund
	K. Norrman		K. Norrman
	Ericsson		Ericsson
	April 2004		November 2004
	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-11.txt>		<draft-ietf-mmusic-kmgmt-ext-12.txt>
	Status of this memo		Status of this memo
	By submitting this Internet-Draft, I certify that any applicable		By submitting this Internet-Draft, I certify that any applicable
	patent or other IPR claims of which I am (we are) aware have been		patent or other IPR claims of which I am (we are) aware have been
	disclosed, and any of which I (we) become aware will be disclosed, in		disclosed, and any of which I (we) become aware will be disclosed, in
	accordance with RFC 3668 (BCP 79).		accordance with RFC 3668 (BCP 79).
	By submitting this Internet-Draft, I accept the provisions of Section		By submitting this Internet-Draft, I accept the provisions of Section
	3 of RFC 3667 (BCP 78).		3 of RFC 3667 (BCP 78).
	skipping to change at page 2, line 20		skipping to change at page 2, line 20
	be used by one or more key management protocols. As such, their use		be used by one or more key management protocols. As such, their use
	is meaningful only when complemented by an appropriate key management		is meaningful only when complemented by an appropriate key management
	protocol.		protocol.
	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. The usage with the MIKEY key management		together with SIP and RTSP. The usage with the MIKEY key management
	protocol is also defined.		protocol is also defined.
	TABLE OF CONTENTS		TABLE OF CONTENTS
	1. Introduction.....................................................2		1. Introduction.....................................................3
	1.1. Notational Conventions.........................................4		1.1. Notational Conventions.........................................4
	2. Extensions to SDP and RTSP.......................................4		2. Extensions to SDP and RTSP.......................................4
	2.1. SDP Extensions.................................................4		2.1. SDP Extensions.................................................5
	2.2. RTSP Extensions................................................5		2.2. RTSP Extensions................................................5
	3. Usage with SDP, SIP, RTSP, and SAP...............................6		3. Usage with SDP, SIP, RTSP, and SAP...............................6
	3.1. Use of SDP.....................................................7		3.1. Use of SDP.....................................................7
	3.1.1 General processing............................................7		3.1.1 General processing............................................7
	3.1.2 Use of SDP with offer/answer and SIP..........................9		3.1.2 Use of SDP with offer/answer and SIP..........................9
	3.1.3 Use of SDP with SAP..........................................10		3.1.3 Use of SDP with SAP..........................................11
	3.1.4 Bidding-down attack prevention...............................11		3.1.4 Bidding-down attack prevention...............................11
	3.2. RTSP usage....................................................12		3.2. RTSP usage....................................................13
	4. Example scenarios...............................................14		4. Example scenarios...............................................15
	5. Adding further Key management protocols.........................18		5. Adding further Key management protocols.........................19
	6. Integration of MIKEY............................................19		6. Integration of MIKEY............................................20
	6.1 MIKEY Interface................................................19		6.1 MIKEY Interface................................................20
	7. Security Considerations.........................................20		7. Security Considerations.........................................21
	8. IANA Considerations.............................................21		8. IANA Considerations.............................................23
	8.1. SDP Attribute Registration....................................21		8.1. SDP Attribute Registration....................................23
	8.2. RTSP Registration.............................................22		8.2. RTSP Registration.............................................23
	8.3. Protocol Identifier Registration..............................22		8.3. Protocol Identifier Registration..............................23
	9. Acknowledgments.................................................23		9. Acknowledgments.................................................24
	10. Author's Addresses.............................................23		10. Author's Addresses.............................................25
	11. References.....................................................24		11. References.....................................................25
	11.1. Normative References.........................................24		11.1. Normative References.........................................25
	11.2. Informative References.......................................24		11.2. Informative References.......................................26
	1. Introduction		1. Introduction
	[RFC Editor remark] All instances of RFC xxxx should be replaced		[RFC Editor remark] All instances of RFC xxxx should be replaced
	with the RFC number of this document, when published. Furthermore,		with the RFC number of this document, when published.
	all instances of RFC yyyy should be replaced with the RFC number
	of the MIKEY (Multimedia Internet KEYing) document [MIKEY], when
	published.
	There has recently been work to define a security profile for the		There has recently been work to define a security profile 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 solution to		However, a security protocol needs a key management solution to
	exchange keys and security parameters, manage and refresh keys, etc.		exchange keys and security parameters, manage and refresh keys, etc.
	A key management protocol is executed prior to the security		A key management protocol is executed prior to the security
	protocol's execution. The key management protocol's main goal is to,		protocol's execution. The key management protocol's main goal is to,
	in a secure and reliable way, establish a security association for		in a secure and reliable way, establish a security association for
	the security protocol. This includes one or more cryptographic keys		the security protocol. This includes one or more cryptographic keys
	skipping to change at page 3, line 54		skipping to change at page 4, line 5
	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		* The possibility to negotiate keying material end-to-end without
	applying end-to-end protection of the SDP (instead, hop-by-hop		applying end-to-end protection of the SDP (instead, hop-by-hop
	security mechanisms can be used which may be useful if		security mechanisms can be used which may be useful if
	intermediate proxies needs access to the SDP).		intermediate proxies needs access to the SDP).
	Currently in SDP [SDPnew], there exists one field to transport keys,		Currently in SDP [SDPnew], there exists one field to transport keys,
	the "k=" 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, and the "k=" field is not extendible. The approach used		transported, and the "k=" field is not extensible. The approach used
	is to extend the SDP description through a number of attributes that		is to extend the SDP description through a number of attributes that
	transport the key management offer/answer and also to associate it		transport the key management offer/answer and also to associate it
	with the media sessions. SIP uses the offer/answer model [OAM]		with the media sessions. SIP uses the offer/answer model [OAM]
	whereby extensions to SDP will be enough. However, RTSP [RTSP] does		whereby extensions to SDP will be enough. However, RTSP [RTSP] does
	not use the offer/answer model with SDP, so a new RTSP header is		not use the offer/answer model with SDP, so a new RTSP header is
	introduced to convey key management data.		introduced to convey key management data.
	The document also defines the use of the described framework together		The document also defines the use of the described framework together
	with the key management protocol Multimedia Internet KEYing (MIKEY)		with the key management protocol Multimedia Internet KEYing (MIKEY)
	[MIKEY].		[MIKEY].
	skipping to change at page 5, line 7		skipping to change at page 5, line 15
	2.1. SDP Extensions		2.1. SDP Extensions
	This section provides an ABNF grammar (as used in [SDPnew]) for the		This section provides an ABNF grammar (as used in [SDPnew]) for the
	key management extensions to SDP.		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
	The att-field and att-value for the key management extensions are as		The ABNF for the key management extensions (conforming to the att-
	follow:		field and att-value) are as follow:
			key-mgmt-attribute = key-mgmt-att-field ":" key-mgmt-att-value
	key-mgmt-att-field = "key-mgmt"		key-mgmt-att-field = "key-mgmt"
	key-mgmt-att-value = 0*1SP prtcl-id SP keymgmt-data		key-mgmt-att-value = 0*1SP prtcl-id SP keymgmt-data
	prtcl-id = KMID		prtcl-id = KMID
	; e.g. "mikey"		; e.g. "mikey"
	keymgmt-data = base64		keymgmt-data = base64
	SP = 0x20		SP = 0x20
	where KMID is as defined in Section 2 of this memo, base64 is as		where KMID is as defined in Section 2 of this memo, base64 is as
	defined in SDP [SDPnew]. Prtcl-id refers to the set of values defined		defined in SDP [SDPnew]. Prtcl-id refers to the set of values defined
	for KMID in Section 8.		for KMID in Section 8.
	The attribute MAY be used at session level, media level, or at both		The 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. In other words, if the media level		defined at session level. In other words, if the media level
	attribute is present, the session level attribute MUST be ignored for		attribute is present, the session level attribute MUST be ignored for
	this media. Section 3.1 describes in detail how the attributes are		this media. Section 3.1 describes in detail how the attributes are
	used and how the SDP is handled in different usage scenarios.		used and how the SDP is handled in different usage scenarios. The
			choice of the level depends for example on the particular key
			management protocol. Some protocols may not be able to derive enough
			key material for all the sessions; furthermore, possibly a different
			protection to each session could be required. The particular protocol
			might achieve this only by specifying it at the media level. Other
			protocols, such as MIKEY, have instead those capabilities (as it can
			express multiple security policies and derive multiple keys), so it
			may use the session level.
	2.2. RTSP Extensions		2.2. RTSP Extensions
	To support the key management attributes, the following RTSP header		To support the key management attributes, the following RTSP header
	is defined:		is defined:
	KeyMgmt = "KeyMgmt" ":" key-mgmt-spec 0*("," key-mgmt-spec)		KeyMgmt = "KeyMgmt" ":" key-mgmt-spec 0*("," key-mgmt-spec)
	key-mgmt-spec = "prot" "=" KMID ";" ["uri" "=" <"> rtsp_URL <"> ";"]		key-mgmt-spec = "prot" "=" KMID ";" ["uri" "=" <"> rtsp_URL <"> ";"]
	"data" "=" base64		"data" "=" base64
	where KMID is as defined in Section 2 of this memo, "base64" as		where KMID is as defined in Section 2 of this memo, "base64" as
	defined in [SDPnew], and "rtsp_URL" as defined in [RTSP].		defined in [SDPnew], and "rtsp_URL" as defined in [RTSP].
	The "uri" parameter identifies the context for which the key		The "uri" parameter identifies the context for which the key
	management data applies, and the RTSP URI SHALL match a (session or		management data applies, and the RTSP URI SHALL match a (session or
	media) URI present in the description of the session. If the RTSP		media) URI present in the description of the session. If the RTSP
	aggregated control URI is included it indicates that the key		aggregated control URI is included it indicates that the key
	skipping to change at page 7, line 7		skipping to change at page 7, line 27
	(to assure that the message is authentic).		(to assure that the message is authentic).
	At the Responder's side, the key management protocol checks the		At the Responder's side, the key management protocol checks the
	validity of the key management message, together with the		validity of the key management message, together with the
	availability of the parameters offered, and then provides the key		availability of the parameters offered, and then provides the key
	management data to be included in the answer. This answer may		management data to be included in the answer. This answer may
	typically authenticate the Responder to the Initiator, and also state		typically authenticate the Responder to the Initiator, and also state
	if the initial offer was accepted or not. Certain protocols might		if the initial offer was accepted or not. Certain protocols might
	require the Responder to include a selection of the security		require the Responder to include a selection of the security
	parameters that he is willing to support. Again, the actual content		parameters that he is willing to support. Again, the actual content
	of such response is dependent on the particular key management		of such responses is dependent on the particular key management
	protocol.		protocol.
	Section 6 describes a realization of the MIKEY protocol using these		Section 6 describes a realization of the MIKEY protocol using these
	mechanisms. Procedures to be used when mapping new key management		mechanisms. Procedures to be used when mapping new key management
	protocols onto this framework are described in Section 5.		protocols onto this framework are described in Section 5.
	3.1. Use of SDP		3.1. Use of SDP
	This section describes the processing rules for the different		This section describes the processing rules for the different
	applications which use SDP for the key management.		applications which use SDP for the key management.
	skipping to change at page 9, line 32		skipping to change at page 9, line 53
	* Before, or in conjunction with, passing the key management data to		* Before, or in conjunction with, passing the key management data to
	the key management protocol, the complete list of protocol		the key management protocol, the complete list of protocol
	identifier from the offer message is provided by the SDP		identifier from the offer message is provided by the SDP
	application to the key management protocol (as defined in Section		application to the key management protocol (as defined in Section
	3.1.4).		3.1.4).
	When an answer is created, the following offer-answer specific		When an answer is created, the following offer-answer specific
	procedure SHALL be applied:		procedure SHALL be applied:
	* If the key management rejects the offer, the answerer SHOULD return		* If the key management rejects the offer, the answerer SHOULD return
	a "606 Not Acceptable" message, optionally also including one or		a "488 Not Acceptable Here" message, optionally also including one
	more Warning headers (a 306 "Attribute not understood" when one of		or more Warning headers (a 306 "Attribute not understood" when one
	the parameters is not supported, and a 399 "Miscellaneous warning"		of the parameters is not supported, and a 399 "Miscellaneous
	with arbitrary information to be presented to a human user or		warning" with arbitrary information to be presented to a human
	logged, see Section 20.43 in [SIP]). Further details about the		user or logged, see Section 20.43 in [SIP]). Further details about
	cause of failure MAY be described in an included message from the		the cause of failure MAY be described in an included message from
	key management protocol. The session is then aborted (and it is up		the key management protocol. The session is then aborted (and it
	to local policy or end user to decide how to continue).		is up to local policy or end user to decide how to continue).
	Note that the key management attribute (related to the same key		Note that the key management attribute (related to the same key
	management protocol) MAY be present both at session level and at		management protocol) MAY be present both at session level and at
	media level. Consequently, the process SHALL be repeated for each		media level. Consequently, the process SHALL be repeated for each
	such key management attribute detected. In case the key management		such key management attribute detected. In case the key management
	processing of any such attribute does not succeed (e.g.		processing of any such attribute does not succeed (e.g.
	authentication failure, parameters not supported etc.), on either		authentication failure, parameters not supported etc.), on either
	session or media level, the entire session setup SHALL be aborted,		session or media level, the entire session setup SHALL be aborted,
	including those parts of the session which successfully completed		including those parts of the session that successfully completed
	their part of the key management.		their part of the key management.
	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 when using the offer-answer model, each transporting a		initial offer when using the offer-answer model, each transporting a
	different key management protocol, thus indicating supported		different key management protocol, thus indicating supported
	alternatives.		alternatives.
	If the offerer includes more than one key management protocol		If the offerer includes more than one key management protocol
	attribute 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 (the first being the		SHOULD be listed in order of preference (the first being the
	preferred). The answerer selects the key management protocol it		preferred). The answerer selects the key management protocol it
	wishes to use, and processes only it, on either session or media		wishes to use, and processes only it, on either session or media
	level, or on both, according to where located. If the answerer does		level, or on both, according to where located. If the answerer does
	not support any of the offerer's suggested key management protocols,		not support any of the offerer's suggested key management protocols,
	the receiver returns a "606 Not Acceptable" error message, whereby		the receiver returns a "488 Not Acceptable Here" error message,
	the sender MUST abort the current setup procedure.		whereby the sender MUST abort the 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.		computational workload for the offerer will increase drastically.
	Unless the guidelines of Section 3.1.4 are followed, multiple lines		Unless the guidelines of Section 3.1.4 are followed, multiple lines
	may open up bidding-down attacks.		may open up bidding-down attacks. Note also that the multiple offer
			option has been added to optimize signaling overhead in case the
			Initiator knows some key (e.g. a public key) that the Responder has,
			but is unsure of what protocol the Responder supports. The mechanism
			is not intended to negotiate options within one and the same
			protocol.
	The offerer MUST include the key management data within an offer that		The offerer MUST include the key management data within an offer that
	contains the media description it applies to.		contains the media description it applies to.
	Re-keying MUST be handled as a new offer, with the new proposed		Re-keying MUST be handled as a new offer, with the new proposed
	parameters. The answerer treats this as a new offer where the key		parameters. The answerer treats this as a new offer where the key
	management is the issue of change. The re-keying exchange MUST be		management is the issue of change. The re-keying exchange MUST be
	finalized before the security protocol can change the keys. The same		finalized before the security protocol can change the keys. The same
	key management protocol used in the original offer SHALL also be used		key management protocol used in the original offer SHALL also be used
	in the new offer carrying re-keying. If the new offer carrying re-		in the new offer carrying re-keying. If the new offer carrying re-
	keying fails (e.g., the authentication verification fails), the		keying fails (e.g., the authentication verification fails), the
	answerer SHOULD send a "606 Not Acceptable" message, including one or		answerer SHOULD send a "488 Not Acceptable Here" message, including
	more Warning headers (at least a 306). The offerer MUST then abort		one or more Warning headers (at least a 306). The offerer MUST then
	the session.		abort the session.
	Note that, in multicast scenarios, unlike unicast, there is only a		Note that, in multicast scenarios, unlike unicast, there is only a
	single view of the stream [OAM], hence there MUST be a uniform		single view of the stream [OAM], hence there MUST be a uniform
	agreement of the security parameters.		agreement of the security parameters.
			After the offer is issued, the offerer SHOULD be prepared to receive
			media, as the media may arrive prior to the answer. However, this
			brings issues, as the offer does not know yet the answererÆs choice
			in terms of e.g. algorithms, nor possibly the key is know. This can
			cause delay or clipping can occur; if this is unacceptable, the
			offerer SHOULD use mechanisms outside the scope of this document,
			e.g. the security precondition for SIP [SPREC].
	3.1.3 Use of SDP with SAP		3.1.3 Use of SDP with SAP
	There are cases where SDP is used without conforming to the		There are cases where SDP is used without conforming to the
	offer/answer model; instead it is a one-way SDP distribution (i.e.		offer/answer model; instead it is a one-way SDP distribution (i.e.
	without back channel), such as when used with SAP and HTTP.		without back channel), such as when used with SAP and HTTP.
	The processing follows the two first steps of the general SDP		The processing follows the two first steps of the general SDP
	processing (see Section 3.1.1). It can be noted that the processing		processing (see Section 3.1.1). It can be noted that the processing
	in this case differs from the offer/answer case in the fact that only		in this case differs from the offer/answer case in the fact that only
	one key management protocol SHALL be offered (i.e. no negotiation		one key management protocol SHALL be offered (i.e. no negotiation
	skipping to change at page 11, line 43		skipping to change at page 12, line 27
	where KMID is as defined in Section 2.		where KMID is as defined in Section 2.
	For example, if the offered protocols are MIKEY and two yet-to-be-		For example, if the offered protocols are MIKEY and two yet-to-be-
	invented protocols KEYP1, KEYP2, the SDP is:		invented protocols KEYP1, KEYP2, the SDP is:
	v=0		v=0
	o=alice 2891092738 2891092738 IN IP4 lost.example.com		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.example.com		c=IN IP4 lost.example.com
	a=key-mgmt:mikey ddOoF9sdhskd727ghuiSDsdhsoKko7eWsnDSJD...		a=key-mgmt:mikey AQAFgM0XflABAAAAAAAAAAAAAAsAyO...
	a=key-mgmt:keyp1 727gkdOshsuiSDF9sdhsdKnD/dhsoSJokdo7eWD...		a=key-mgmt:keyp1 727gkdOshsuiSDF9sdhsdKnD/dhsoSJokdo7eWD...
	a=key-mgmt:keyp2 DFsnuiSDSh9sdh Kksd/dhsoddo7eOok727gWsJD...		a=key-mgmt:keyp2 DFsnuiSDSh9sdh Kksd/dhsoddo7eOok727gWsJD...
	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 each specified 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).
	Each of the three protocols includes this protocol identifier		Each of the three protocols includes this protocol identifier
	list in its authentication coverage (according to its protocol		list in its authentication coverage (according to its protocol
	specification).		specification).
	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 all acceptable protocols are included in the first		RECOMMENDED that all acceptable protocols are included in the first
	offer, rather than making single, subsequent alternative offers in		offer, rather than making single, subsequent alternative offers in
	response to error messages, see "Security Considerations".		response to error messages, see "Security Considerations".
			End-to-end integrity protection of the key-mgmt attributes
			altogether, provided externally to the key management themselves,
			also gives protection against this bidding down attack. This is for
			example the case if SIP uses S/MIME [RFC3851] to end-to-end integrity
			protect the SDP description. As however this end-to-end protection is
			not an assumption of the framework, the mechanisms defined in this
			section SHALL be applied.
	3.2. RTSP usage		3.2. 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 modifying RTSP) to send		some problems, as it is not possible (without modifying RTSP) to send
	back an answer. To solve this, a new header has been introduced		back an answer. To solve this, a new header has been introduced
	(Section 2.2). This also assumes that the key management also has		(Section 2.2). This also assumes that the key management also has
	some kind of binding to the media, so that the response to the server		some kind of binding to the media, so that the response to the server
	will be processed as required.		will be processed as required.
	The server SHALL be the Initiator of the key management exchange for		The server SHALL be the Initiator of the key management exchange for
	skipping to change at page 14, line 28		skipping to change at page 15, line 22
	written.		written.
	4. Example scenarios		4. Example scenarios
	The following examples utilize MIKEY [MIKEY] as the key management		The following examples utilize MIKEY [MIKEY] as the key management
	protocol to be integrated into SDP and RTSP (see Section 5.1.).		protocol to be integrated into SDP and RTSP (see Section 5.1.).
	Example 1 (SIP/SDP)		Example 1 (SIP/SDP)
	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 w-land.example.com		o=alice 2891092738 2891092738 IN IP4 w-land.example.com
	s=Cool stuff		s=Cool stuff
	e=alice@w-land.example.com		e=alice@w-land.example.com
	t=0 0		t=0 0
	c=IN IP4 w-land.example.com		c=IN IP4 w-land.example.com
	a=key-mgmt:mikey uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...		a=key-mgmt:mikey AQAFgM0XflABAAAAAAAAAAAAAAsAyONQ6gAAAAAGEEoo2pee4hp2
			UaDX8ZE22YwKAAAPZG9uYWxkQGR1Y2suY29tAQAAAAAAAQAk0JKpgaVkDaawi9whVBtBt
			0KZ14ymNuu62+Nv3ozPLygwK/GbAV9iemnGUIZ19fWQUOSrzKTAv9zV
	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 (signaled by the use of the SAVP profile). She		that run over SRTP (signaled by the use of the SAVP profile). She
	uses MIKEY to set up the security parameters for SRTP (Section 6).		uses MIKEY to set up the security parameters for SRTP (Section 6).
	The MIKEY message contains the security parameters, together with the		The MIKEY message contains the security parameters, together with the
	necessary key material. Note that MIKEY is exchanging the crypto		necessary key material. Note that MIKEY is exchanging the crypto
	suite for both streams, as it is placed at the session level. Also,		suite for both streams, as it is placed at the session level. Also,
	MIKEY provides its own security, i.e. when Bob processes Alice's		MIKEY provides its own security, i.e. when Bob processes Alice's
	MIKEY message, he will also find the signaling of the security		MIKEY message, he will also find the signaling of the security
	parameters used to secure the MIKEY exchange. Alice's authentication		parameters used to secure the MIKEY exchange. Alice's endpoint's
	information is also carried within the MIKEY message, to prove that		authentication information is also carried within the MIKEY message,
	the message is authentic.		to prove that the message is authentic. The above MIKEY message is an
			example of message when the pre-shared method MIKEY is used.
	Upon receiving the offer, Bob checks the validity of the received		Upon receiving the offer, Bob checks the validity of the received
	MIKEY message, and, in case of successful verification, he accepts		MIKEY message, and, in case of successful verification, he accepts
	the offer and sends an answer back to Alice (with his authentication		the offer and sends an answer back to Alice (with his authentication
	information, and, if necessary, also some key material from his		information, and, if necessary, also some key material from his
	side):		side):
	v=0		v=0
	o=bob 2891092897 2891092897 IN IP4 foo.example.com		o=bob 2891092897 2891092897 IN IP4 foo.example.com
	s=Cool stuff		s=Cool stuff
	e=bob@foo.example.com		e=bob@foo.example.com
	t=0 0		t=0 0
	c=IN IP4 foo.example.com		c=IN IP4 foo.example.com
	a=key-mgmt:mikey skaoqDeMkdwRW278HjKVB...		a=key-mgmt:mikey AQEFgM0XflABAAAAAAAAAAAAAAYAyONQ6gAAAAAJAAAQbWlja2
			V5QG1vdXNlLmNvbQABn8HdGE5BMDXFIuGEga+62AgY5cc=
	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
	Upon receiving the answer, Alice verifies the correctness of it. In		Upon receiving the answer, Alice verifies the correctness of it. In
	case of success, at this point Alice and Bob share the security		case of success, at this point Alice and Bob share the security
	parameters and the keys needed for a secure RTP communication.		parameters and the keys needed for a secure RTP communication.
	Example 2 (SDP)		Example 2 (SDP)
	skipping to change at page 15, line 43		skipping to change at page 16, line 40
	previous case, but applies only to the audio stream.		previous case, but applies only to the audio stream.
	v=0		v=0
	o=alice 2891092738 2891092738 IN IP4 w-land.example.com		o=alice 2891092738 2891092738 IN IP4 w-land.example.com
	s=Cool stuff		s=Cool stuff
	e=alice@w-land.example.com		e=alice@w-land.example.com
	t=0 0		t=0 0
	c=IN IP4 w-land.example.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 AQAFgM0XflABAAAAAAAAAAAAAAsAy...
	m=video 52230 RTP/AVP 31		m=video 52230 RTP/AVP 31
	a=rtpmap:31 H261/90000		a=rtpmap:31 H261/90000
	Bob would then act as described in the previous example, including		Bob would then act as described in the previous example, including
	the MIKEY answer at the media level for the audio stream (as Alice		the MIKEY answer at the media level for the audio stream (as Alice
	did).		did).
	Note that even if the key management attribute were specified at		Note that even if the key management attribute were specified at
	session level, the video part would 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, instead the RTP/AVP profile is		security profile is not used, instead the RTP/AVP profile is
	skipping to change at page 16, line 35		skipping to change at page 17, line 35
	Content-Type: application/sdp		Content-Type: application/sdp
	Content-Length: 478		Content-Length: 478
	v=0		v=0
	o=actionmovie 2891092738 2891092738 IN IP4 movie.example.com		o=actionmovie 2891092738 2891092738 IN IP4 movie.example.com
	s=Action Movie		s=Action Movie
	e=action@movie.example.com		e=action@movie.example.com
	t=0 0		t=0 0
	c=IN IP4 movie.example.com		c=IN IP4 movie.example.com
	a=control:rtsp://movie.example.com/action		a=control:rtsp://movie.example.com/action
	a=key-mgmt:mikey uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD..		a=key-mgmt:mikey AQAFgM0XflABAAAAAAAAAAAAAAsAy...
	m=audio 0 RTP/SAVP 98		m=audio 0 RTP/SAVP 98
	a=rtpmap:98 AMR/8000		a=rtpmap:98 AMR/8000
	a=control:rtsp://movie.example.com/action/audio		a=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
	a=control:rtsp://movie.example.com/action/video		a=control:rtsp://movie.example.com/action/video
	The client checks the validity of the received MIKEY message, and, in		The client checks the validity of the received MIKEY message, and, in
	case of successful verification, it accept the message. The client		case of successful verification, it accept the message. The client
	then includes its key management data in the SETUP request going back		then includes its key management data in the SETUP request going back
	to the server, the client authentication information (to prove that		to the server, the client authentication information (to prove that
	the message is authentic) and, if necessary, some key material.		the message is authentic) and, if necessary, some key material.
	SETUP rtsp://movie.example.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; uri="rtsp://movie.example.com/action";		keymgmt: prot=mikey; uri="rtsp://movie.example.com/action";
	data="skaoqDeMkdwRW278HjKVB..."		data="AQEFgM0XflABAAAAAAAAAAAAAAYAyONQ6g..."
	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
	Note than in this case the key management line was specified at the		Note than in this case the key management line was specified at the
	skipping to change at page 17, line 45		skipping to change at page 18, line 45
	v=0		v=0
	o=actionmovie 2891092738 2891092738 IN IP4 movie.example.com		o=actionmovie 2891092738 2891092738 IN IP4 movie.example.com
	s=Action Movie		s=Action Movie
	e=action@movie.example.com		e=action@movie.example.com
	t=0 0		t=0 0
	c=IN IP4 movie.example.com		c=IN IP4 movie.example.com
	a=control:rtsp://movie.example.com/action		a=control:rtsp://movie.example.com/action
	m=audio 0 RTP/SAVP 98		m=audio 0 RTP/SAVP 98
	a=rtpmap:98 AMR/8000		a=rtpmap:98 AMR/8000
	a=key-mgmt:mikey uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD..		a=key-mgmt:mikey AQAFgM0XflABAAAAAAAAAAAAA...
	a=control:rtsp://movie.example.com/action/audio		a=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
	a=key-mgmt:mikey dhsoKkdOokdo7eWsnDSJDuiSDF9sdhs727ghsd/..		a=key-mgmt:mikey AQAFgM0AdlABAAAAAAAAAAAAA...
	a=control:rtsp://movie.example.com/action/video		a=control:rtsp://movie.example.com/action/video
	Each RTSP header are inserted in the SETUP related to the audio and		Each RTSP header are inserted in the SETUP related to the audio and
	video separately:		video separately:
	SETUP rtsp://movie.example.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; uri="rtsp://movie.example.com/action/audio";		keymgmt: prot=mikey; uri="rtsp://movie.example.com/action/audio";
	data="skaoqDeMkdwRW278HjKVB..."		data="AQEFgM0XflABAAAAAAAAAAAAA..."
	and similarly for the video session:		and similarly for the video session:
	SETUP rtsp://movie.example.com/action/video RTSP/1.0		SETUP rtsp://movie.example.com/action/video RTSP/1.0
	CSeq: 315		CSeq: 315
	Transport: RTP/SAVP/UDP;unicast;client_port=3058-3059		Transport: RTP/SAVP/UDP;unicast;client_port=3058-3059
	keymgmt: prot=mikey; uri="rtsp://movie.example.com/action/video";		keymgmt: prot=mikey; uri="rtsp://movie.example.com/action/video";
	data="RW278HjKVBskaoqDeMkdw..."		data="AQEFgM0AdlABAAAAAAAAAAAAAA..."
	Note: The "uri" parameter could be excluded from the two SETUP		Note: The "uri" parameter could be excluded from the two SETUP
	messages in this example.		messages in this example.
	5. Adding further Key management protocols		5. Adding further Key management protocols
	This framework cannot be used with all key management protocols. The		This framework cannot be used with all key management protocols. The
	key management protocol needs to comply with the requirements		key management protocol needs to comply with the requirements
	described in Section 3. In addition to this, the following needs to		described in Section 3. In addition to this, the following needs to
	be defined:		be defined:
	skipping to change at page 20, line 41		skipping to change at page 21, line 39
	7. Security Considerations		7. Security Considerations
	The framework for transfer of key management data as described here		The framework for transfer of key management data as described here
	is intended to provide the security parameters for the end-to-end		is intended to provide the security parameters for the end-to-end
	protection of the media session. It is furthermore good practice to		protection of the media session. It is furthermore good practice to
	secure the session setup (e.g. SDP, SIP, RTSP, SAP). However, it		secure the session setup (e.g. SDP, SIP, RTSP, SAP). However, it
	might be that the security of the session setup is not possible to		might be that the security of the session setup is not possible to
	achieve end-to-end, but only hop-by-hop. For example, SIP requires		achieve end-to-end, but only hop-by-hop. For example, SIP requires
	intermediate proxies to have access to part of the SIP message, and		intermediate proxies to have access to part of the SIP message, and
	sometimes also to the SDP description (c.f. [E2M]). General security		sometimes also to the SDP description (c.f. [E2M]), although end-to-
	considerations for the session setup can be found in SDP [SDPnew],		end confidentiality can hide bodies from intermediaries. General
	SIP [SIP], and RTSP [RTSP]. The framework defined in this memo is		security considerations for the session setup can be found in SDP
	useful when the session setup is not protected in an end-to-end		[SDPnew], SIP [SIP], and RTSP [RTSP]. The framework defined in this
	fashion, but the media streams needs to be end-to-end protected,		memo is useful when the session setup is not protected in an end-to-
	hence the security parameters such as keys are not wanted revealed to		end fashion, but the media streams needs to be end-to-end protected,
	intermediaries.		hence the security parameters (such as keys) are not wanted revealed
			to nor manipulated by intermediaries.
	The security will also depend on the encapsulated level of security		The security will also depend on the encapsulated level of security
	the key management protocol offers. It follows that, under the		the key management protocol offers. It follows that, under the
	assumption that the key management schemes are secure, the SDP can be		assumption that the key management schemes are secure, the SDP can be
	passed along unprotected without affecting the key management as		passed along unencrypted without affecting the key management as
	such, and the media streams will still be secure even if some		such, and the media streams will still be secure even if some
	attackers gained knowledge of the SDP contents. Further security		attackers gained knowledge of the SDP contents. Further security
	considerations can be found for each key management protocol (for		considerations can be found for each key management protocol (for
	MIKEY these can be found in [MIKEY]).		MIKEY these can be found in [MIKEY]). However, if the SDP messages
			are not sent integrity protected between the parties, it is possible
	However, if the SDP messages are not sent authenticated between the		for an active attacker to change attributes without being detected.
	parties, it is possible for an active attacker to change attributes		As the key management protocol may (indirectly) rely on some of the
	without being detected. As the key management protocol may		session information from SDP (e.g., address information), an attack
	(indirectly) rely on some of the session information from SDP (e.g.,		on SDP may have indirect consequences on the key management. Even if
	address information), an attack on SDP may have indirect consequences		the key management protocol does not rely on parameters of SDP and
	on the key management. Even if the key management protocol does not		will not be affected by manipulation of these, different DoS attacks
	rely on parameters of SDP and will not be affected by manipulation of		aimed at SDP may lead to undesired interruption in the setup. See
	these, different DoS attacks aimed at SDP may lead to undesired		also the attacks described at the end of this section.
	interruption in the setup.
	The use of multiple key management protocols in the same offer may		The use of multiple key management protocols in the same offer may
	open up the possibility of a bidding-down attack, as specified in		open up the possibility of a bidding-down attack, as specified in
	Section 3.1.4. To exclude such possibility, the authentication of the		Section 3.1.4. To exclude such possibility, the authentication of the
	protocol identifier list is used. Note though, that the security		protocol identifier list is used. Note though, that the security
	level of the authenticated protocol identifier will be as high (or		level of the authenticated protocol identifier will be as high (or
	low), as the "weakest" protocol. Therefore, it is discouraged to		low), as the "weakest" protocol. Therefore, it is discouraged to
	offer protocols with too different security levels.		offer protocols with too different security levels.
	Note that it is impossible to assure the authenticity of a declined		Note that it is impossible to assure the authenticity of a declined
	skipping to change at page 21, line 38		skipping to change at page 22, line 36
	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. In		service that can be avoided by following the above recommendation.
	the case that the response declines any security (therefore there is		Note also that the declined offer could be result of an attacker who
	impossibility of authenticating it), the session setup SHALL be		sits on the path and removes all the key management offers. The
	aborted.		bidding-down attack prevention, as described above, would not work in
			this case (as the answerer receives no key management attribute).
			Also here it is impossible to assure the authenticity of a declined
			offer, though here the reason is the "peeling-off" attack. It is up
			to the local policy to decide the behavior in the case that the
			response declines any security (therefore there is impossibility of
			authenticating it). If for example the local policy requires a secure
			communication and cannot accept an unsecured one, then the session
			setup SHALL be aborted.
	8. IANA Considerations		8. IANA Considerations
	8.1. SDP Attribute Registration		8.1. SDP Attribute Registration
	A new SDP attribute needs to be registered 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@ericsson.com		mailto: fredrik.lindholm@ericsson.com
	skipping to change at page 22, line 51		skipping to change at page 24, line 13
	following registration created initially: "mikey".		following registration created initially: "mikey".
	Contact: Fredrik Lindholm		Contact: Fredrik Lindholm
	mailto: fredrik.lindholm@ericsson.com		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-att-field		Purpose: Usage of MIKEY with the key-mgmt-att-field
	attribute and the keymgmt RTSP header		attribute and the keymgmt RTSP header
	Reference: Section 7 in RFC yyyy		Reference: Section 7 in RFC 3830
	Note that this registration implies that the protocol identifier,		Note that this registration implies that the protocol identifier,
	KMID, name space will be shared between SDP and RTSP.		KMID, name space will be shared between SDP and RTSP.
	Further values may be registered according to the "Specification		Further values may be registered according to the "Specification
	Required" policy as defined in [RFC2434]. Each new registration needs		Required" policy as defined in [RFC2434]. Each new registration needs
	to indicate the parameter name, and register it within IANA. Note		to indicate the parameter name, and register it within IANA. Note
	that the parameter name is case sensitive and it is RECOMMENDED that		that the parameter name is case sensitive and it is RECOMMENDED that
	the name to be in lower case letters. For each new registration, it		the name to be in lower case letters. For each new registration, it
	is mandatory that a permanent, stable, and publicly accessible		is mandatory that a permanent, stable, and publicly accessible
	skipping to change at page 23, line 29		skipping to change at page 24, line 42
	* Value name: the name of the value being registered (which MUST		* Value name: the name of the value being registered (which MUST
	comply with the KMID as defined in Section 2)		comply with the KMID as defined in Section 2)
	* Long Name: long-form name in English		* Long Name: long-form name in English
	* Purpose: short explanation of the purpose of the registered name.		* Purpose: short explanation of the purpose of the registered name.
	* Reference: a reference to the specification (e.g. RFC number)		* Reference: a reference to the specification (e.g. RFC number)
	providing the usage guidelines in accordance to Section 5 (and		providing the usage guidelines in accordance to Section 5 (and
	also complying to the specified requirements).		also complying to the specified requirements).
	9. Acknowledgments		9. Acknowledgments
	The authors would like to thank Joerg Ott, Rolf Blom, Magnus Brolin,		The authors would like to thank Rolf Blom, Johan Bilien, Magnus
	Johan Bilien, Jon-Olov Vatn, and Erik Eliasson. A special thanks to		Brolin, Erik Eliasson, Martin Euchner, Joerg Ott, Jon Peterson, and
	Colin Perkins and Magnus Westerlund, who contributed in many		Jon-Olov Vatn. A special thanks to Colin Perkins and Magnus
	sections.		Westerlund, who contributed in many sections.
	10. Author's Addresses		10. 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
	skipping to change at page 24, line 19		skipping to change at page 25, line 37
	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@ericsson.com		Sweden EMail: karl.norrman@ericsson.com
	11. References		11. References
	11.1. Normative References		11.1. Normative References
	[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 3830.
	[Internet Draft, <draft-ietf-msec-mikey-08.txt>].
	[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, RFC 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		[RFC2119] Bradner, S. "Key words for use in RFCs to Indicate
	Requirement Levels", IETF, RFC 2119.		Requirement Levels", IETF, RFC 2119.
	skipping to change at page 24, line 51		skipping to change at page 26, line 18
	[RFC2434] 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		[RFC3548] Josefsson, S., "The Base16, Base32, and Base64 Data
	Encodings", IETF, RFC 3548.		Encodings", IETF, RFC 3548.
	11.2. Informative References		11.2. Informative References
	[E2M] Ono, K. and Tachimoto, S., "End-to-middle security in the		[E2M] Ono, K. and Tachimoto, S., "End-to-middle security in the
	Session Initiation Protocol (SIP)", Internet Draft, IETF, draft-ono-		Session Initiation Protocol (SIP)", Internet Draft, IETF, draft-ono-
	sipping-end2middle-security-01.		sipping-end2middle-security-03.
	[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.
			[RFC3851] Ramsdell, B., "Secure/Multipurpose Internet Mail Extensions
			(S/MIME) Version 3.1 Message Specification", IETF, RFC 3851.
	[SRTP] Baugher, M., McGrew, D., Naslund, M., Carrara, E., Norrman,		[SRTP] Baugher, M., McGrew, D., Naslund, M., Carrara, E., Norrman,
	K., "The Secure Real-time Transport Protocol", IETF, RFC 3711.		K., "The Secure Real-time Transport Protocol", IETF, RFC 3711.
			[SPREC] Andreasen, F., Baugher, M., and Wing, D., "Security
			Preconditions for Session Description Protocol Media Streams", work
			in progress, February 2004.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2004). This document is subject		Copyright (C) The Internet Society (2004). This document is subject
	to the rights, licenses and restrictions contained in BCP 78, and		to the rights, licenses and restrictions contained in BCP 78, and
	except as set forth therein, the authors retain all their rights.		except as set forth therein, the authors retain all their rights.
	Disclaimer of Validity		Disclaimer of Validity
	This document and the information contained herein are provided on an		This document and the information contained herein are provided on an
	"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS		"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
	OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET		OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
	ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,		ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
	INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE		INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
	INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED		INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
	WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.		WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	This Internet-Draft expires in October 2004.		This Internet-Draft expires in April 2005.
End of changes.
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