draft-ietf-mmusic-kmgmt-ext-05.txt		draft-ietf-mmusic-kmgmt-ext-06.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: December 2002 M. Naslund		Expires: August 2003 M. Naslund
	K. Norrman		K. Norrman
	Ericsson		Ericsson
	June, 2002		February, 2003
	Key Management Extensions for SDP and RTSP		Key Management Extensions for SDP and RTSP
	<draft-ietf-mmusic-kmgmt-ext-05.txt>		<draft-ietf-mmusic-kmgmt-ext-06.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 2, line 14		skipping to change at page 2, line 14
	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.......................................3
	2.1. SDP Extensions.................................................4		2.1. SDP Extensions.................................................4
	2.2. RTSP Extensions................................................4		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......................................................6
	3.3. RTSP usage.....................................................7		3.3. RTSP usage.....................................................7
	3.4. Example scenarios..............................................8		3.4. Example scenarios..............................................7
	4. Adding further Key management protocols.........................10		4. Adding further Key management protocols.........................10
	5. Security Considerations.........................................10		5. Security Considerations.........................................10
	6. IANA Considerations.............................................11		6. IANA Considerations.............................................11
	7. Conclusions.....................................................11		7. Conclusions.....................................................11
	8. Acknowledgments.................................................11		8. Acknowledgments.................................................11
	9. Author's Addresses..............................................11		9. Author's Addresses..............................................11
	10. References.....................................................12		10. References.....................................................12
	10.1. Normative References.........................................12		10.1. Normative References.........................................12
	10.2. Informative References.......................................12		10.2. Informative References.......................................12
	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.
	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 so-called security association for the
	security protocol. This includes one or several cryptographic keys		security protocol. This includes one or several cryptographic keys
	and a set of necessary parameters for the security protocol, e.g.,		and a set of necessary parameters for the security protocol, e.g.,
	cipher and authentication algorithm to be used. The key management		cipher and authentication algorithm to be used. The key management
	protocol has similarities with, e.g., SIP [SIP] and RTSP [RTSP] in		protocol has similarities with, e.g., SIP [SIP] and RTSP [RTSP] in
	the sense that it negotiates necessary information in order to be		the sense that it negotiates necessary information in order to be
	able to setup the session.		able to setup the session.
	The focus in the following sections is to describe SDP attribute		The focus in the following sections is to describe SDP attribute
	extensions and RTSP header extensions to support key management, and		extensions and RTSP header extensions to support key management, and
	a possible integration within SIP and RTSP. A framework is therefore		a possible integration within SIP and RTSP. A framework is therefore
	skipping to change at page 3, line 22		skipping to change at page 3, line 22
	* 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.
	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 "key=" field. However, this is not enough for a key management
	protocol. The approach here is to use and extend the SDP description		protocol as there are many more parameters that need to be
	to transport the key management offer/answer and also to associate it		transported. The approach here is to use and extend the SDP
	with the media sessions. SIP uses the offer/answer model [OAM]		description to transport the key management offer/answer and also to
	whereby extensions to SDP will be enough. However, RTSP [RTSP] does		associate it with the media sessions. SIP uses the offer/answer model
	not use the offer/answer model. This makes it impossible to send back		[OAM] whereby extensions to SDP will be enough. However, RTSP [RTSP]
	an answer to the server. To solve this, a new header is introduced in		does not use the offer/answer model. This makes it impossible to send
	which the key management data can be included.		back an answer to the server. To solve this, a new header is
			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 RFC-2119.
	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
	skipping to change at page 3, line 53		skipping to change at page 4, line 5
	For the SDP description, the key management attributes MAY be defined		For the SDP description, the key management attributes MAY be defined
	at session level (i.e. before the media descriptor lines) and/or at		at session level (i.e. before the media descriptor lines) and/or at
	media level. If the key management attributes are defined at media		media level. If the key management attributes are defined at media
	level, they 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.
	The following SDP attribute is defined:		The following SDP attribute is defined:
	key-mgmt:<name> <opaque-data>		key-mgmt:<identifier> <opaque-data>
	<name> is the name of the key management protocol and the opaque-data
	is a field to transport the key management protocol data. The key		<identifier> is the name of the key management protocol and the
	management protocol data contains the necessary information to		opaque-data is a field to transport the key management protocol data.
	establish the security protocol, e.g., keys and cryptographic		The key management protocol data contains the necessary information
			to establish the security protocol, e.g., keys and cryptographic
	parameters. All parameters and keys are protected by the key		parameters. All parameters and keys are protected by the key
	management. Note that if the key management protocol fails, e.g., the		management. Note that if the key management protocol fails, e.g., the
	receiver does not accept any of the proposed security parameters, or		receiver does not accept any of the proposed security parameters, or
	simply does not understand the key management protocol, the security		simply does not understand the key management protocol, the security
	setup will fail. Consequently, it is impossible to establish a secure		setup will fail. Consequently, it is impossible to establish a secure
	session. So, if the key management fails, the offer must be rejected.		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
	One new attribute for SDP is defined:		One new attribute for SDP is defined:
	key-mgmt = "key-mgmt: " prtcl-name keymgmt-data		key-mgmt = "key-mgmt: " prtcl-id keymgmt-data
	prtcl-name = 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.		defined at session level.
	2.2. RTSP Extensions		2.2. RTSP Extensions
	To support the needed attribute described, the following RTSP header		To support the needed attribute described, the following RTSP header
	is defined:		is 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
	skipping to change at page 5, line 37		skipping to change at page 5, line 37
	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-name field.		Kerberos) MUST be put in the prtcl-id field.
	* The keymgmt-data field MUST be created with the data received from		* The keymgmt-data field MUST be created with the data received from
	the key management protocol (this data MUST be base64 encoded).		the key management protocol (this data MUST be base64 encoded).
	The data may e.g. be a MIKEY message or Kerberos ticket.		The data may e.g. be a MIKEY message 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 process these attributes in the following manner:
	* The key management protocol used MUST be identified by checking the		* The key management protocol used MUST be identified by checking the
	prtcl-name field in the key management attribute.		prtcl-id field in the key management attribute.
	* The key management data from the keymgmt-data field MUST be		* The key management data from the keymgmt-data field MUST be
	extracted and given to the key management protocol. Note that		extracted and given to the key management protocol. Note that
	depending on key management protocol, some extra parameters might		depending on key management protocol, some extra parameters might
	of course be requested, such as the source/destination network		of course be requested, such as the source/destination network
	address/port(s) for the specified media.		address/port(s) for the specified media.
	* 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 accepted or not), the processing can proceed
	according to normal processing (e.g. according to the offer/answer		according to normal processing (e.g. according to the offer/answer
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	Note that the attribute MAY be repeated more than once (e.g., one at		Note that the attribute MAY be repeated more than once (e.g., one at
	session level and one at media level). Consequently, the process is		session level and one at media level). Consequently, the process is
	repeated for each key management attribute detected.		repeated for each key management attribute detected.
	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 alternatives supported.
	If the sender includes more than one key management attributes at		If the sender includes more than one key management protocol
	session level (analogous for the media level), these SHOULD be listed		attributes at session level (analogous for the media level), these
	in order of preference (with the first being the preferred). The		SHOULD be listed in order of preference (with the first being the
	receiver chooses the key management protocol it supports. When		preferred). The receiver chooses the key management protocol it
	answering, only the accepted key management attribute MUST be		supports. When answering, only the accepted key management protocol
	included. If the receiver does not support any of the sender's		attribute MUST be included. If the receiver does not support any of
	suggested key management protocols, the receiver answers with an		the sender's suggested key management protocols, the receiver answers
	error message (see SIP and RTSP), possibly also listing the supported		with an error message (see SIP and RTSP), whereby the sender MUST put
	key management protocols (without any data included).		down the current setup procedure.
	However, the offerer is RECOMMENDED to include only one of the
	protocols for a specific media. If the answerer cannot support the
	proposed protocol, it rejects the offer.
	Note that by placing multiple key management offers in a single		Note that by placing 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. It		computational workload for the offerer will increase drastically. The
	might be acceptable to use a trial and error approach if the number		possibility to support multiple key management protocols may
	of key management protocols supported are few. The possibility to		introduce bidding down attacks. To avoid this, the list of
	support multiple key management protocols may introduce bidding down		identifiers of the proposed key management protocols MUST be
	attacks. It is therefore important that the local policy considers		authenticated, which MUST be done by each key management. This puts
	this (e.g., only allows protocols that from a security point of view		the requirement that it MUST be specified (in the key management
	are equivalent, to be negotiated).		protocol itself or in a companion document) how the protocol
			identifiers could be authenticated from the offerer to the responder
	What can be done to increase the likelihood for a successful setup is		by the use of the specific key management protocol. Note that even if
	to use a capability discovery mechanism (e.g., used in SIP when using		only one key management protocol is used, that still must
	the OPTION message). In this case, the key management protocols		authenticate its own protocol identifier.
	supported are expressed at session level without any data (i.e., a
	list of only the key-mgmt:<name> part is used).
	v=0		If more than one protocol is supported by the offerer, it is
	o=alice 2891092738 2891092738 IN IP4 lost.somewhere.com		RECOMMENDED that he offers all to him acceptable protocols in the
	c=IN IP4 lost.somewhere.com		first offer, rather than making single, subsequent alternative offers
	a=key-mgmt:mikey		in response to error messages, see "Security Considerations".
	a=key-mgmt:coolxchg
	m=audio 0 RTP/SAVP 98
	a=rtpmap:98 AMR/8000
	m=video 0 RTP/SAVP 31 34
	a=rtpmap:31 H261/90000
	a=rtpmap:34 H263/90000
	3.2. SIP usage		3.2. SIP usage
	The offerer SHOULD include the key management data within an offer		The offerer SHOULD include the key management data within an offer
	that contains the media description it should apply to. The answerer		that contains the media description it should apply to. The answerer
	MUST check with the key management protocol if the attribute values		MUST check with the key management protocol if the attribute values
	are valid, and then obtain from the key management the data to		are valid, and then obtain from the key management the data to
	include in the answer.		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 offerer MAY then go out with a new (different) offer,		a 306). The offer MUST then abort the security setup.
	depending on the local security policy.
	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 synchronization
	method used when changing keys are dependent on the security and key		method used when changing keys are dependent on the security and key
	management protocol used.		management protocol used.
	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 have 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 processing of a key management header in RTSP should be done
	analogous of the SDP message processing. The initial key management		analogous of the SDP message processing. The initial key management
	message from a server should be sent to the client using SDP. When		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		responding to this, the client uses the new RTSP header to send back
	an answer (included in the SETUP message). If a server receives a		an answer (included in the SETUP message). If a server receives a
	SETUP message in which it expects a key management message, but none		SETUP message in which it expects a key management message, but none
	is included, a 403 Forbidden SHOULD be returned to the client.		is included, a 403 Forbidden SHOULD be returned to the client,
			whereby the current setup MUST be aborted.
	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
	skipping to change at page 10, line 21		skipping to change at page 10, line 12
	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
	video followed by a PLAY message).		video followed by a PLAY message).
	4. Adding further Key management protocols		4. 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. To be able to use a key management protocol		described in Section 3. To be able to use a key management protocol
	with this framework, the following MUST be specified:		with this framework, the following MUST be specified:
	* the key management protocol name that should be used in the		* the key management protocol identifier that should be used in the
	protocol name fields in both SDP and RTSP (e.g. "mikey" for		protocol identifier fields in both SDP and RTSP (e.g. "mikey" for
	MIKEY).		MIKEY).
	* the information the key management needs from SDP and RTSP (Section		* the information the key management needs from SDP and RTSP (Section
	3 gives a guideline of what SDP and RTSP needs from the key		3 gives a guideline of what SDP and RTSP needs from the key
	management). The exact API is implementation specific, but it		management). The exact API is implementation specific, but it
	SHOULD at least support to exchange the specified information.		SHOULD at least support to exchange the specified information.
			Note that in particular, the key management MUST always be given
			the protocol identifier(s) of the key management protocol(s)
			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
	consideration.		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 the intention of		security of the media sessions. It is therefore not a primary
	this document to describe possible security solutions or to define		intention of this document to describe possible security solutions or
	possible security problems. The defined SDP and RTSP extensions are		to define possible security problems. The defined SDP and RTSP
	not believed to introduce any new security risks to SDP and RTSP.		extensions are not believed to introduce any new 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. In general, it is therefore a good thing, not		on the key management. In general, it is therefore a good thing, not
	only to try to secure the session, but also to secure the session		only to try to secure the session, but also to secure the session
	setup.		setup.
			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
			he/she declines the offer usually means that he/she does not support
			the protocol(s) offered, and consequently cannot be expected to
			authenticate the response either. This means that if the initiator is
			unsure of which protocol(s) the responder supports, we RECOMMEND that
			the initiator offers all acceptable protocols in a single offer. If
			not, this opens up the possibility for a "man-in-the-middle" (MITM)
			to affect the outcome of the eventually agreed upon protocol, by
			faking unauthenticated error messages until the initiator 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 service that
			can be avoided by following the above recommendation.
	6. IANA Considerations		6. IANA Considerations
	New attribute fields for SDP (see Section 2.1) and RTSP header are		New attribute fields for SDP (see Section 2.1) and RTSP header are
	registered (see Section 2.2).		registered (see Section 2.2).
	7. Conclusions		7. 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
	skipping to change at page 12, line 19		skipping to change at page 12, line 27
	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@era.ericsson.se
	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
	SDP", Internet Draft, IETF, Work in progress (MMUSIC).		the Session Description Protocol (SDP)", IETF, 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.
	[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).
	[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 2543.
	skipping to change at page 12, line 44		skipping to change at page 12, line 52
	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", Internet Draft,		Norrman, K., "MIKEY: Multimedia Internet KEYing", Internet Draft,
	IETF, Work in progress (MSEC).		IETF, 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 December 2002.		This Internet-Draft expires in August 2003.
End of changes.
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