draft-ietf-mmusic-kmgmt-ext-00.txt		draft-ietf-mmusic-kmgmt-ext-01.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: May 2002 M. Naslund		Expires: July 2002 M. Naslund
	K. Norrman		K. Norrman
	Ericsson		Ericsson
	November, 2001		January, 2002
	Key Management Extensions for SDP and RTSP		Key Management Extensions for SDP and RTSP
	<draft-ietf-mmusic-kmgmt-ext-00.txt>		<draft-ietf-mmusic-kmgmt-ext-01.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 36		skipping to change at page 1, line 36
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	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
	Abstract		Abstract
	Work for securing real-time applications have started. It has also
	brought toward the need for a key management infrastructure to
	support the security protocol.
	This document defines extensions for SDP and RTSP to carry the		This document defines extensions for SDP and RTSP to carry the
	security information needed by a key management protocol, in order to		security information needed by a key management protocol, in order to
	secure the media stream itself.		secure the media stream. Indications are also given on how it should
			be used 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. SDP Attribute Fields for Key Management.......................3		2. Extensions to SDP and RTSP.................................... 3
	2.1. SDP Grammar.................................................4		2.1. SDP Extensions.............................................. 3
	2.2. SDP in SIP and RTSP.........................................5		2.2. RTSP Extensions............................................. 4
	3. RTSP Header and Grammar.......................................5		3. Usage with SIP and RTSP....................................... 5
	4. Security Considerations.......................................6		3.1. SIP usage................................................... 5
	5. IANA Considerations...........................................6		3.2. RTSP usage.................................................. 5
	6. Conclusions...................................................7		3.3. Example scenarios........................................... 6
	7. Acknowledgments...............................................7		4. Security Considerations....................................... 8
	8. Author's Addresses............................................7		5. IANA Considerations........................................... 9
	9. References....................................................7		6. Conclusions................................................... 9
			7. Acknowledgments............................................... 9
			8. Author's Addresses............................................ 9
			9. References....................................................10
	1. Introduction		1. Introduction
	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, managing and refreshing keys,
	etc.		etc.
	The Session Description Protocol [SDP] is used to convey		The focus in the following sections is to describe SDP attribute
	advertisements of conference sessions and communicate the relevant		extensions and RTSP header extensions to support key management, and
	conference setup information to prospective participants. SDP is		a possible integration within SIP and RTSP.
	intended to use different transport protocols as appropriate, e.g.
	the Session Initiation Protocol [SIP] and the Real-Time Streaming
	Protocol [RTSP].
	An efficient way of performing key management is to integrate it into
	SDP. This approach may reduce the number of roundtrips compared to a
	standalone key management scheme (and in some cases it could also
	reduce the total bandwidth consumption). However, to make it possible
	to integrate the key management protocol (e.g. [MIKEY]) into SDP, a
	set of attributes in SDP is needed. Such a set of attributes is
	defined in this document to support integrated media stream key
	management.
	Currently in SDP, one field exists to transport keys, i.e. the "key="
	field. However, this is not enough for a key management protocol.
	There MUST exist the possibility to include not only the key, but
	also the key encrypted, encryption parameters, security protocol
	parameters, and at the same time have it all authenticated. This can
	not be done with the "key=" field as specified today.
	In RTSP, the SDP description is mainly used in the response to the
	DESCRIBE method. This makes it hard to send key management messages
	back from the client to the server. Therefore, this draft also
	defines an RTSP header that may be used to carry additional key
	management messages.
	1.1. Notational Conventions
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
	this document are to be interpreted as described in RFC-2119.
	2. SDP Attributes for Key Management
	This subsection describes common attributes that are to be included		Some of the motivations to include the key management in the session
	in the SDP description when an integrated key management protocol is		establishment are:
	used. All attribute values MUST follow the general SDP guidelines.
	The attributes are designed to give a minimal impact on SDP, i.e.		* Just as the codec information is a description of how to encode
	only a minimal set of "knowledge" MUST be built into an existing SDP		and decode the audio (or video) stream, the key management data
	stack in order to support the key management.		is a description of how to encrypt and decrypt the data.
	Three SDP attributes are defined.		* The possibility to negotiate the security for the entire
			multimedia session at the same time.
	To be able to detect the key management protocol applied, this MUST		* The knowledge of the media at the session establishment makes it
	be signaled by:		easy to tie the key management to the multimedia sessions.
	a=keymgmt-prot:<protocol>		* This approach may be more efficient than setting up the security
			later, as that approach might force extra roundtrips, possibly
			also a separate set-up for each stream, hence implying more delay
			to the actual setup of the media session.
	The key management protocol data MUST be provided in the following		Currently in SDP [SDP], one field exists to transport keys, i.e. the
	field:		"key=" field. However, this is not enough for a key management
			protocol. The approach here is to use and extend the SDP description
			to transport the key management offer/answer and also to associate it
			with the media sessions. SIP uses the offer/answer model [OAM]
			whereby extensions to SDP will be enough. An extra RTSP header is
			also defined.
	a=keymgmt-data:<key-transport-data>		1.1. Notational Conventions
	Note that the data MUST be encoded in a way so that it complies with		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	the normal SDP rules.		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
			document are to be interpreted as described in RFC-2119.
	In case the key management mechanism does not provide authentication		2. Extensions to SDP and RTSP
	of the key management part, additional authentication data MAY be
	provided in the "keymgmt-auth" field.
	a=keymgmt-auth:<key-auth-data>		This section describes common attributes that are to be included in
			an SDP description or in an RTSP header when an integrated key
			management protocol is used. All attribute values MUST follow the
			general SDP or RTSP guideline.
	The key management attributes may be defined both at the session		For the SDP description, the key management attributes may be defined
	level (i.e. before the media descriptor lines) and at the media level		at session level (i.e. before the media descriptor lines) and/or at
	of the SDP description. If the key management attributes are defined		media level. If the key management attributes are defined at media
	at media level, it will only apply to that specific media. If the key		level, they will only apply to that specific media. If the key
	management attributes are defined at both session and media level,		management attributes are defined at both session and media level,
	the media level definition overrides the session level definition for		the media level definition overrides the session level definition for
	that specific media.		that specific media.
	Example 1 (session level)		The extensions were defined in a way to:
	a=keymgmt-prot:MIKEY		* give a minimal impact on current SDP implementations, i.e. only
	a=keymgmt-data:uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...		minimal modifications MUST be built into an existing SDP stack in
	m=audio 49000 RTP/SAVP 98		order to support the key management.
	a=rtpmap:98 AMR/8000
	m=video 2232 RTP/SAVP 31
	In this example, MIKEY is negotiating the crypto suite for both		* make it easy to use another key management protocol, or a new
	streams at session level. It is recommended to use this approach if		version, without having to redefine the attributes or add new
	possible to save both bandwidth and computational resources.		ones.
	Example 2 (media level)		The following set of attributes have been identified as necessary to
			support:
	m=audio 49000 RTP/SAVP 98		* key management protocol identifier, to indicate the key
	a=keymgmt-prot:MIKEY		management protocol used ('keymgmt-prtcl')
	a=keymgmt-data:uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...
	a=rtpmap:98 AMR/8000
	m=video 2232 RTP/AVP 31
	Note that the video part in this example is not protected by any		* key management raw data field, to transport the key management
	security protocol.		protocol data ('keymgmt-data')
	2.1. SDP Grammar		* in the case of SDP, an extra (optional) authentication attribute
			to be able to tie the key management data to the surrounding
			media definitions ('key-extra-auth').
			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 [SDP]) for the key management extensions to SDP.		(as used in [SDP]) 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
	Three new attributes are defined, keymgmt-prtcl, keymgmt-data, and		Three new attributes are defined, keymgmt-prtcl, keymgmt-data, and
	key-extra-auth.		key-extra-auth.
	keymgmt-prtcl = "keymgmt-prot:" prtcl-name		keymgmt-prtcl = "keymgmt-prot:" prtcl-name
	prtcl-name = 1*(alpha-numeric|SAFE)		prtcl-name = 1*(safe)
	; e.g. "MIKEY"		; e.g. "MIKEY"
	keymgmt-data = "keymgmt-data:" byte-string		keymgmt-data = "keymgmt-data:" byte-string
	key-extra-auth = "keymgmt-auth:" byte-string		key-extra-auth = "keymgmt-auth:" byte-string
	byte-string = 1*(0x01..0x09|0x0b|0x0c|0x0e..0xff)		where safe and byte-string are as defined in SDP [SDP].
	;any byte except NUL, CR or LF
	alpha-numeric = ALPHA | DIGIT
	DIGIT = "0" | POS-DIGIT		2.2. RTSP Extensions
	POS-DIGIT = "1"|"2"|"3"|"4"|"5"|"6"|"7"|"8"|"9"		To support the three different attributes described, the following
			RTSP header is defined:
	ALPHA = "a"|"b"|"c"|"d"|"e"|"f"|"g"|"h"|"i"|"j"|"k"|		KeyMgmt = "KeyMgmt" ":" [stream-url] protocol data
	"l"|"m"|"n"|"o"|"p"|"q"|"r"|"s"|"t"|"u"|"v"|
	"w"|"x"|"y"|"z"|"A"|"B"|"C"|"D"|"E"|"F"|"G"|
	"H"|"I"|"J"|"K"|"L"|"M"|"N"|"O"|"P"|"Q"|"R"|
	"S"|"T"|"U"|"V"|"W"|"X"|"Y"|"Z"
	SAFE = "\$" | "-" | "_" | "." | "+"		stream-url = "url" "=" url ";"
	2.2. SDP in SIP and RTSP		protocol = "Prot" "=" token ";"
	Both SIP and RTSP provide means to transport SDP descriptions. This		data = "Data" "=" quoted-string
	section gives a recommendation of how/when to include key management
	initiated SDP descriptions in SIP and RTSP.
	For SIP, the recommendation is to use the Invite message (and the		url, token and quoted-string are as defined in the RTSP specification
	following response) to transport the SDP description with the key		[RTSP]. The url indicates the stream URL, which the parameters
	management parameters.		correspond to.
	For RTSP, the recommendation is to let the server include a SDP		The KeyMgmt header should be possible to use in both request and
	description with the key management parameters in the response to a		response messages of the following methods:
	DESCRIBE message. A problem with RTSP is that no SDP description can		* DESCRIBE
	be assumed to be sent back to the server. Therefore, other means to		* ANNOUNCE
	send key management messages between client and server is needed.		* SETUP
	This may be solved by using the new RTSP header defined in Section 3.		* PLAY
			* RECORD
			* SET_PARAMETER
			* GET_PARAMETER
			* OPTIONS
	In general, any key management protocol using SDP as a mean of		3. Usage with SIP and RTSP
	transport, MUST not require a great number of exchange messages. It
	is RECOMMENDED that the key management protocol does not use more
	than one roundtrip. This is to create as small (if any) impact as
	possible on the underlying transporting mechanism (e.g., SIP and
	RTSP).
	3. RTSP Header and Grammar		This section gives recommendations of how/when to include the defined
			key management attributes when SIP and/or RTSP are used together with
			SDP.
	To support the three different parameters described in Section 2, a		Some general requirements MUST be set on the key management protocol
	new RTSP header is defined.		if it has to be suitable to work together with SIP and RTSP:
	KeyMgmt = "KeyMgmt" ":" [stream-url] protocol data [auth]		* It MUST be possible to execute the key management protocol in at
			most one roundtrip in case the answerer accepts the offer.
	stream-url = "url" "=" url ";"		* The protocol MUST return, to SDP/RTSP, a valid answer whether the
			provided offer was accepted or not.
	protocol = "Prot" "=" prtcl-name		* There MUST be a possibility for the key management protocol to
	data = ";" "Data" "=" string		tie the media sessions to the negotiated parameters (i.e. an
			interface between the key management and the SDP and RTSP
			implementation MUST exist).
	auth = ";" "Auth" "=" string		Today, the MIKEY protocol has adopted the key management extensions
			to work together with SIP and RTSP. Other protocols may use the
			described attributes and header, e.g. Kerberos.
	string = 1*(alpha-numeric|SAFE|"=")		3.1. SIP usage
	alpha-numeric, SAFE and prtcl-name are as defined in Section 2.1. The		The offerer should include the key management data within an offer
	url indicates the stream URL for which the parameters correspond to.		that contains the media description it should apply to. The answerer
	It is recommended that the string is a base64 encoded value.		MUST check with the key management protocol if the attribute values
			are valid, and then obtain from the key management the data to
			include in the answer. If the offer is not accepted, the answerer
			returns a notification message and the offerer may go out with a new
			(different) offer, depending on the local security policy.
	The new key management header should be possible to use in both		Re-keying should be handled as a new offer, i.e. a re-INVITE should
	request and response messages of the following methods:		be sent with the new proposed parameters. The answerer treats this as
	* ANNOUNCE		a new offer where the key management is the issue of change.
	* SETUP
	* PLAY
	* RECORD
	* SET_PARAMETER
	* GET_PARAMETER
	* OPTIONS
	When a key management protocol is enabled in the RTSP implementation,		3.2. RTSP usage
	it MUST for each message to be sent (that may contain the KeyMgmt
	header), check with the key management protocol if any parameters(s)		RTSP does not use the offer/answer model, as SIP does. This causes
	should be include in the header (i.e. the Data or Auth parameter).		some problems as it is not possible (without abusing RTSP) to send
	For each message received (that contains the KeyMgmt header), the key		back an answer to the server (as the server will in most cases be the
	management parameters (Data and Auth) are passed to the key		one initiating the security parameter exchange). To solve this, a new
	management protocol for processing.		header has been introduced (Section 2.2).
			The initial key management message from a server should be sent to
			the client using SDP. When responding to this, the client uses the
			new RTSP header to send back an answer (included in either the SETUP
			or the PLAY message).
			The server may provide re-keying facilities by sending a new key
			management message in a SET_PARAMETER or ANNOUNCE messages. In the
			latter, the RTSP header is not used if the ANNOUNCE message includes
			a SDP description where the data can be provided in. The response
			message is then put in the new RTSP header in the response message
			from the client to the server. Note that the SET PARAMETER and the
			ANNOUNCE messages are not mandatory to support for the servers.
			3.3. Example scenarios
			Example 1 (SIP)
			A SIP call is taking place between Alice and Bob. Alice sends an
			Invite message consisting of the following offer:
			v=0
			o=alice 2891092738 2891092738 IN IP4 lost.somewhere.com
			s=Cool stuff
			e=alice@w-land.org
			t=0 0
			c=IN IP4 lost.somewhere.com
			a=keymgmt-prot:MIKEY
			a=keymgmt-data:uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...
			m=audio 49000 RTP/SAVP 98
			a=rtpmap:98 AMR/8000
			m=video 52230 RTP/SAVP 31
			a=rtpmap:31 H261/90000
			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
			uses MIKEY. Note that MIKEY is negotiating the crypto suite for both
			streams (as it is placed at the session level).
			Bob accepts the offer and sends an answer back to Alice:
			v=0
			o=bob 2891092897 2891092897 IN IP4 found.somewhere.com
			s=Cool stuff
			e=bob@null.org
			t=0 0
			c=IN IP4 found.somewhere.com
			a=keymgmt-prot:MIKEY
			a=keymgmt-data:skaoqDeMkdwRW278HjKVB...
			m=audio 49030 RTP/SAVP 98
			a=rtpmap:98 AMR/8000
			m=video 52230 RTP/SAVP 31
			a=rtpmap:31 H261/90000
			Example 2 (SDP)
			This example shows how Alice would have done in the previous example
			if she wished to protect only the audio stream.
			v=0
			o=alice 2891092738 2891092738 IN IP4 lost.somewhere.com
			s=Cool stuff
			e=alice@w-land.org
			t=0 0
			c=IN IP4 lost.somewhere.com
			m=audio 49000 RTP/SAVP 98
			a=rtpmap:98 AMR/8000
			a=keymgmt-prot:MIKEY
			a=keymgmt-data:uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...
			m=video 52230 RTP/AVP 31
			a=rtpmap:31 H261/90000
			Example 3 (RTSP)
			A client wants to set up a streaming session and requests a media
			description from the streaming server.
			DESCRIBE rtsp://server.example.com/fizzle/foo RTSP/1.0
			CSeq: 312
			Accept: application/sdp
			From: user@client.com
			The server sends back an OK message including a SDP description. As
			the server
			RTSP/1.0 200 OK
			CSeq: 312
			Date: 23 Jan 1997 15:35:06 GMT
			Content-Type: application/sdp
			v=0
			o=actionmovie 2891092738 2891092738 IN IP4 movie.somewhere.com
			s=Action Movie
			e=action@movie.somewhere.com
			t=0 0
			c=IN IP4 movie.somewhere.com
			a=keymgmt-prot:MIKEY
			a=keymgmt-data:uiSDF9sdhs727ghsd/dhsoKkdOokdo7eWsnDSJD...
			m=audio 0 RTP/SAVP 98
			a=rtpmap:98 AMR/8000
			control:rtsp://movie.somewhere.com/action/audio
			m=video 0 RTP/SAVP 31
			a=rtpmap:31 H261/90000
			control:rtsp://movie.somewhere.com/action/video
			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.
			the SETUP message).
			SETUP rtsp://movie.somewhere.com/action/audio RTSP/1.0
			CSeq: 313
			Transport: RTP/SAVP/UDP;unicast;client_port=3056-3057
			KeyMgmt: Prot=MIKEY;Data="skaoqDeMkdwRW278HjKVB..."
			The server processes the request including checking the validity of
			the key management header.
			RTSP/1.0 200 OK
			CSeq: 313
			Session: 12345678
			Transport: RTP/SAVP/UDP;unicast;client_port=3056-3057;
			server_port=5000-5001
			The RTSP is then proceeded as usual (with e.g. a SETUP message for
			the video followed by a PLAY message).
	4. Security Considerations		4. Security Considerations
	The nature of this document is to allow SDP and RTSP support for		The nature of this document is to allow SDP and RTSP to support
	security of the media sessions. It is therefore not the intention of		security of the media sessions. It is therefore not the intention of
	this document to describe possible security solution nor define		this document to describe possible security solution or to define
	possible security problems. The defined SDP and RTSP extensions are		possible security problems. The defined SDP and RTSP extensions are
	not believed to introduce any new security risks to SDP and RTSP.		not believed to introduce any new security risks to SDP and RTSP.
			The 'key-extra-auth' attribute may be (optionally) used to guarantee
			an authenticated binding between the session(s) and the security
			parameters, e.g. authenticating both the key management lines and
			(parts of) the surrounding SDP description. Each key management
			specifies the coverage of such 'key-extra-auth' attribute. A denial-
			of-service attack may be open if such authenticated binding is not
			provided. Note however, the 'key-extra-auth' cannot work when NATs
			are present.
	Note that the purpose of the key management fields is to secure the		Note that the purpose of the key management fields is to secure the
	media streams themselves. Provided that the key management schemes		media streams themselves. Under the assumption that the key
	are secure, the SDP payloads can be passed along unprotected, and the		management schemes are secure, the SDP payloads can be passed along
	media streams will still be secure even if some attackers gained		unprotected, and the media streams will still be secure even if some
	knowledge of the SDP contents. There may, however, be other reasons		attackers gained knowledge of the SDP contents. There may however, be
	to protect the SDP payloads such as preventing attackers from gaining		other reasons to protect the SDP payloads such as preventing
	any information regarding the session or the used equipment.		attackers from gaining any information regarding the session or the
			used equipment.
	5. IANA Considerations		5. IANA Considerations
	Three new attributes fields for SDP (see Section 2) and one new RTSP		Three new attributes fields for SDP (see Section 2.1) and one new
	header are registered (see Section 3).		RTSP header are registered (see Section 2.2).
	6. Conclusions		6. Conclusions
	A security solution for real-time applications needs a key management		A security solution for real-time applications needs a key management
	infrastructure. Integrating the key management scheme with the		infrastructure. Integrating the key management scheme with the
	session establishment protocol could be done efficiently in most of		session establishment protocol could be done efficiently in most of
	the scenarios. This document defines extensions to SDP and RTSP so		the scenarios. A set of new attributes and headers have been defined
	that it will be possible to integrate a key management protocol (e.g.		in SDP and RTSP so that it will be possible to integrate a key
	MIKEY) into protocol such as SIP and RTSP.		management protocol (e.g. MIKEY) into SIP and RTSP.
	7. Acknowledgments		7. Acknowledgments
	Thanks to: Joerg Ott, Colin Perkins, Magnus Westerlund, and the rest		Thanks to: Rolf Blom, Joerg Ott, Colin Perkins, Magnus Westerlund,
	involved in the MMUSIC WG and the MSEC WG.		and the rest involved in the MMUSIC WG and the MSEC WG.
	8. Author's Addresses		8. 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 8, line 5		skipping to change at page 10, line 11
	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@era.ericsson.se
	9. References		9. 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", Internet Draft,		Norrman, K., "MIKEY: Multimedia Internet KEYing", Internet Draft,
	IETF, Work in progress (MSEC).		IETF, Work in progress (MSEC).
			[OAM] Rosenberg, J. and Schulzrinne, H., "An Offer/Answer Model with
			SDP", Internet Draft, IETF, Work in progress (MMUSIC).
	[RTSP] Schulzrinne, H., Rao, A., and Lanphier, R., "Real Time		[RTSP] Schulzrinne, H., Rao, A., and Lanphier, R., "Real Time
	Streaming Protocol (RTSP)", RFC 2326, April 1998.		Streaming Protocol (RTSP)", RFC 2326, April 1998.
	[SDP] Handley, M., and Jacobson, V., "Session Description Protocol		[SDP] Handley, M., and Jacobson, V., "Session Description Protocol
	(SDP)", IETF, RFC2327		(SDP)", IETF, RFC2327
	[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, RFC2543.		"SIP: Session Initiation Protocol", IETF, RFC2543.
	[SRTP] Blom, R., Carrara, E., McGrew, D., Naslund, M, Norrman, K.,		[SRTP] Blom, R., Carrara, E., McGrew, D., Naslund, M, Norrman, K.,
	and Oran, D., "The Secure Real Time Transport Protocol", Internet		and Oran, D., "The Secure Real Time Transport Protocol", Internet
	Draft, IETF, Work in Progress (AVT).		Draft, IETF, Work in Progress (AVT).
	This Internet-Draft expires in May 2002.		This Internet-Draft expires in July 2002.
End of changes.
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