draft-ietf-sipbrandy-osrtp-07.txt		draft-ietf-sipbrandy-osrtp-08.txt
	SIPBRANDY Working Group A. Johnston		SIPBRANDY Working Group A. Johnston
	Internet-Draft Villanova University		Internet-Draft Villanova University
	Intended status: Informational B. Aboba		Intended status: Informational B. Aboba
	Expires: June 6, 2019 Microsoft		Expires: September 27, 2019 Microsoft
	A. Hutton		A. Hutton
	Atos		Atos
	R. Jesske		R. Jesske
	Deutsche Telekom		Deutsche Telekom
	T. Stach		T. Stach
	Unaffiliated		Unaffiliated
	December 3, 2018		March 26, 2019
	An Opportunistic Approach for Secure Real-time Transport Protocol		An Opportunistic Approach for Secure Real-time Transport Protocol
	(OSRTP)		(OSRTP)
	draft-ietf-sipbrandy-osrtp-07		draft-ietf-sipbrandy-osrtp-08
	Abstract		Abstract
	Opportunistic Secure Real-time Transport Protocol (OSRTP) is an		Opportunistic Secure Real-time Transport Protocol (OSRTP) is an
	implementation of the Opportunistic Security mechanism, as defined in		implementation of the Opportunistic Security mechanism, as defined in
	RFC 7435, applied to Real-time Transport Protocol (RTP). OSRTP		RFC 7435, applied to Real-time Transport Protocol (RTP). OSRTP
	allows encrypted media to be used in environments where support for		allows encrypted media to be used in environments where support for
	encryption is not known in advance, and not required. OSRTP does not		encryption is not known in advance, and not required. OSRTP does not
	require SDP extensions or features and is fully backwards compatible		require SDP extensions or features and is fully backwards compatible
	with existing implementations using encrypted and authenticated media		with existing implementations using encrypted and authenticated media
	skipping to change at page 1, line 49 ¶		skipping to change at page 1, line 49 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on June 6, 2019.		This Internet-Draft will expire on September 27, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2019 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 29 ¶		skipping to change at page 2, line 29 ¶
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Applicability Statement . . . . . . . . . . . . . . . . . 3		1.1. Applicability Statement . . . . . . . . . . . . . . . . . 3
	2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3		2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
	3. SDP Offer/Answer Considerations . . . . . . . . . . . . . . . 3		3. SDP Offer/Answer Considerations . . . . . . . . . . . . . . . 3
	3.1. Generating the Initial OSRTP Offer . . . . . . . . . . . 4		3.1. Generating the Initial OSRTP Offer . . . . . . . . . . . 4
	3.2. Generating the Answer . . . . . . . . . . . . . . . . . . 4		3.2. Generating the Answer . . . . . . . . . . . . . . . . . . 4
	3.3. Offerer Processing the Answer . . . . . . . . . . . . . . 4		3.3. Offerer Processing the Answer . . . . . . . . . . . . . . 4
	3.4. Modifying the Session . . . . . . . . . . . . . . . . . . 4		3.4. Modifying the Session . . . . . . . . . . . . . . . . . . 5
	4. Security Considerations . . . . . . . . . . . . . . . . . . . 5		4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
	6. Implementation Status . . . . . . . . . . . . . . . . . . . . 5		6. Implementation Status . . . . . . . . . . . . . . . . . . . . 5
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
	8.1. Normative References . . . . . . . . . . . . . . . . . . 6		8.1. Normative References . . . . . . . . . . . . . . . . . . 6
	8.2. Informative References . . . . . . . . . . . . . . . . . 7		8.2. Informative References . . . . . . . . . . . . . . . . . 8
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
	1. Introduction		1. Introduction
	Opportunistic Security [RFC7435] (OS) is an approach to security that		Opportunistic Security [RFC7435] (OS) is an approach to security that
	defines a third mode for security between "cleartext" and		defines a third mode for security between "cleartext" and
	"comprehensive protection" that allows encryption and authentication		"comprehensive protection" that allows encryption and authentication
	to be used if supported but will not result in failures if it is not		of media to be used if supported but will not result in failures if
	supported. In terms of secure media, cleartext is RTP [RFC3550]		it is not supported. In terms of secure media, cleartext is RTP
	media which is negotiated with the RTP/AVP (Audio Video Profile)		[RFC3550] media which is negotiated with the RTP/AVP (Audio Video
	[RFC3551] or the RTP/AVPF profile [RFC4585]. Comprehensive		Profile) [RFC3551] or the RTP/AVPF profile [RFC4585]. Comprehensive
	protection is Secure RTP [RFC3711], negotiated with a secure profile,		protection is Secure RTP [RFC3711], negotiated with a secure profile,
	such as SAVP or SAVPF [RFC5124]. OSRTP allows SRTP to be negotiated		such as SAVP or SAVPF [RFC5124]. OSRTP allows SRTP to be negotiated
	with the RTP/AVP profile, with fallback to RTP if SRTP is not		with the RTP/AVP profile, with fallback to RTP if SRTP is not
	supported.		supported.
	There have been some extensions to SDP to allow profiles to be		There have been some extensions to SDP to allow profiles to be
	negotiated such as SDP Capabilities Negotiation (capneg) [RFC5939] .		negotiated such as SDP Capabilities Negotiation (capneg) [RFC5939] .
	However, these approaches are complex and have very limited		However, these approaches are complex and have very limited
	deployment in communication systems. Other key management protocols		deployment in communication systems. Other key management protocols
	for SRTP have been developed which by design use OS, such as ZRTP		for SRTP have been developed which by design use OS, such as ZRTP
	skipping to change at page 3, line 36 ¶		skipping to change at page 3, line 36 ¶
	OSRTP is a transitional approach that provides a migration path from		OSRTP is a transitional approach that provides a migration path from
	unencrypted communication (RTP) to fully encrypted communication		unencrypted communication (RTP) to fully encrypted communication
	(SRTP). It is only to be used in existing deployments which are		(SRTP). It is only to be used in existing deployments which are
	attempting to transition to fully secure communications. New		attempting to transition to fully secure communications. New
	applications and new deployments will not use OSRTP.		applications and new deployments will not use OSRTP.
	2. Requirements Language		2. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in RFC		"OPTIONAL" in this document are to be interpreted as described in BCP
	2119 [RFC2119].		14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
			appear in all capitals, as shown here.
	3. SDP Offer/Answer Considerations		3. SDP Offer/Answer Considerations
	This section defines the SDP offer/answer considerations for		This section defines the SDP offer/answer considerations for
	opportunistic security.		opportunistic security.
	The procedures are for a specific m- section describing RTP-based		The procedures are for a specific m- section describing RTP-based
	media. If an SDP offer or answer contains multiple such m- sections,		media. If an SDP offer or answer contains multiple such m- sections,
	the procedures are applied to each m- section individually.		the procedures are applied to each m- section individually.
	"Initial OSRTP offer" refers to the offer in which oportunistic		"Initial OSRTP offer" refers to the offer in which oportunistic
	security is offered for an m- section for the first time within an		security is offered for an m- section for the first time within an
	SDP session.		SDP session.
	It is important to note that OSRTP makes no changes, and has no		It is important to note that OSRTP makes no changes, and has no
	effect on media sessions in which the offer contains a secure profile		effect on media sessions in which the offer contains a secure profile
	of RTP, such as SAVP or SAVPF. As discussed in [RFC7435], this is		of RTP, such as SAVP or SAVPF. As discussed in [RFC7435], that is
	the "comprehensive protection" for media mode.		the "comprehensive protection" for media mode.
	3.1. Generating the Initial OSRTP Offer		3.1. Generating the Initial OSRTP Offer
	To indicate support for OSRTP in an SDP offer, the offerer uses the		To indicate support for OSRTP in an SDP offer, the offerer uses the
	RTP/AVP profile [RFC3551] or the RTP/AVPF profile [RFC4585] but		RTP/AVP profile [RFC3551] or the RTP/AVPF profile [RFC4585] but
	includes SRTP keying attributes. OSRTP is not specific to any key		includes SRTP keying attributes. OSRTP is not specific to any key
	management technique for SRTP. For example:		management technique for SRTP and multiple key management techniques
			can be included on the SDP offer. For example:
	If the offerer supports DTLS-SRTP key agreement [RFC5763], then an		If the offerer supports DTLS-SRTP key agreement [RFC5763], then an
	a=fingerprint attribute will be present, or		a=fingerprint attribute will be present, or
	If the offerer supports SDP Security Descriptions key agreement		If the offerer supports SDP Security Descriptions key agreement
	[RFC4568], then an a=crypto attribute will be present, or		[RFC4568], then an a=crypto attribute will be present, or
	If the offerer supports ZRTP key agreement [RFC6189], then an		If the offerer supports ZRTP key agreement [RFC6189], then an
	a=zrtp-hash attribute will be present.		a=zrtp-hash attribute will be present.
	skipping to change at page 4, line 50 ¶		skipping to change at page 5, line 7 ¶
	If the offerer of OSRTP receives an SDP answer which does not contain		If the offerer of OSRTP receives an SDP answer which does not contain
	SRTP keying attributes, then the media session proceeds with RTP. If		SRTP keying attributes, then the media session proceeds with RTP. If
	the SDP answer contains SRTP keying attributes then the associated		the SDP answer contains SRTP keying attributes then the associated
	SRTP key management approach is followed and SRTP media is used for		SRTP key management approach is followed and SRTP media is used for
	this session. If the SRTP key management fails, the media session		this session. If the SRTP key management fails, the media session
	MUST fail.		MUST fail.
	3.4. Modifying the Session		3.4. Modifying the Session
	When an offerer generates a subsequent offer it should do so		When an offerer generates a subsequent SDP offer it should do so
	following the principles of [RFC6337] meaning that the decision to		following the principles of [RFC6337] meaning that the decision to
	create an OSRTP type offer or something else should not be influenced		create the new SDP offer should not be influenced by what was
	by what was previously negotiated. For example if a previous OSRTP		previously negotiated. For example if a previous OSRTP offer did not
	offer did not result in SRTP being established the offerer may try		result in SRTP being established the offerer may try again and
	again and generate a new OSRTP offer as specified in section [3.1].		generate a new OSRTP offer as specified in section [3.1].
	4. Security Considerations		4. Security Considerations
	The security considerations of [RFC7435] apply to OSRTP, as well as		The security considerations of [RFC7435] apply to OSRTP, as well as
	the security considerations of the particular SRTP key agreement		the security considerations of the particular SRTP key agreement
	approach used. However, the authentication requirements of a		approach used. However, the authentication requirements of a
	particular SRTP key agreement approach are relaxed when that key		particular SRTP key agreement approach are relaxed when that key
	agreement is used with OSRTP. For example:		agreement is used with OSRTP, which is consistent with the
			Opportunistic Security approach described [RFC7435]. For example:
	For DTLS-SRTP key agreement [RFC5763], an authenticated signaling		For DTLS-SRTP key agreement [RFC5763], an authenticated signaling
	channel does not need to be used with OSRTP if it is not		channel does not need to be used with OSRTP if it is not
	available.		available.
	For SDP Security Descriptions key agreement [RFC4568], an		For SDP Security Descriptions key agreement [RFC4568], an
	authenticated signaling channel does not need to be used with		authenticated signaling channel does not need to be used with
	OSRTP if it is not available, although an encrypted signaling		OSRTP if it is not available, although an encrypted signaling
	channel must still be used.		channel must still be used.
	skipping to change at page 7, line 46 ¶		skipping to change at page 8, line 5 ¶
	[RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP:		[RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP:
	Media Path Key Agreement for Unicast Secure RTP",		Media Path Key Agreement for Unicast Secure RTP",
	RFC 6189, DOI 10.17487/RFC6189, April 2011,		RFC 6189, DOI 10.17487/RFC6189, April 2011,
	<https://www.rfc-editor.org/info/rfc6189>.		<https://www.rfc-editor.org/info/rfc6189>.
	[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection		[RFC7435] Dukhovni, V., "Opportunistic Security: Some Protection
	Most of the Time", RFC 7435, DOI 10.17487/RFC7435,		Most of the Time", RFC 7435, DOI 10.17487/RFC7435,
	December 2014, <https://www.rfc-editor.org/info/rfc7435>.		December 2014, <https://www.rfc-editor.org/info/rfc7435>.
			[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
			2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
			May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	8.2. Informative References		8.2. Informative References
	[I-D.kaplan-mmusic-best-effort-srtp]		[I-D.kaplan-mmusic-best-effort-srtp]
	Audet, F. and H. Kaplan, "Session Description Protocol		Audet, F. and H. Kaplan, "Session Description Protocol
	(SDP) Offer/Answer Negotiation For Best-Effort Secure		(SDP) Offer/Answer Negotiation For Best-Effort Secure
	Real-Time Transport Protocol", draft-kaplan-mmusic-best-		Real-Time Transport Protocol", draft-kaplan-mmusic-best-
	effort-srtp-01 (work in progress), October 2006.		effort-srtp-01 (work in progress), October 2006.
	[IMTC-SIP]		[IMTC-SIP]
	"Best Practices for SIP Security", IMTC SIP Parity		Group, I. S. P. A., "Best Practices for SIP Security",
			IMTC SIP Parity
	Group http://www.imtc.org/uc/sip-parity-activity-group/,		Group http://www.imtc.org/uc/sip-parity-activity-group/,
	2011, <http://www.imtc.org>.		2011, <http://www.imtc.org>.
	[RFC5939] Andreasen, F., "Session Description Protocol (SDP)		[RFC5939] Andreasen, F., "Session Description Protocol (SDP)
	Capability Negotiation", RFC 5939, DOI 10.17487/RFC5939,		Capability Negotiation", RFC 5939, DOI 10.17487/RFC5939,
	September 2010, <https://www.rfc-editor.org/info/rfc5939>.		September 2010, <https://www.rfc-editor.org/info/rfc5939>.
	[RFC6337] Okumura, S., Sawada, T., and P. Kyzivat, "Session		[RFC6337] Okumura, S., Sawada, T., and P. Kyzivat, "Session
	Initiation Protocol (SIP) Usage of the Offer/Answer		Initiation Protocol (SIP) Usage of the Offer/Answer
	Model", RFC 6337, DOI 10.17487/RFC6337, August 2011,		Model", RFC 6337, DOI 10.17487/RFC6337, August 2011,
	<https://www.rfc-editor.org/info/rfc6337>.		<https://www.rfc-editor.org/info/rfc6337>.
	[RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running		[RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
	Code: The Implementation Status Section", RFC 6982,		Code: The Implementation Status Section", RFC 6982,
	DOI 10.17487/RFC6982, July 2013,		DOI 10.17487/RFC6982, July 2013,
	<https://www.rfc-editor.org/info/rfc6982>.		<https://www.rfc-editor.org/info/rfc6982>.
	[SIPCONNECT]		[SIPCONNECT]
	"SIP-PBX / Service Provider Interoperability SIPconnect		Group, S. F. S. 2. T., "SIP-PBX / Service Provider
	2.0 - Technical Recommendation", SIP Forum http://www.sipf		Interoperability SIPconnect 2.0 - Technical
	orum.org/component/option,com_docman/task,doc_download/		Recommendation", SIP Forum http://www.sipforum.org/compone
	gid,838/Itemid,261/, 2017, <http://www.sipforum.org>.		nt/option,com_docman/task,doc_download/gid,838/
			Itemid,261/, 2017, <http://www.sipforum.org>.
	Authors' Addresses		Authors' Addresses
	Alan Johnston		Alan Johnston
	Villanova University		Villanova University
	Villanova, PA		Villanova, PA
	USA		USA
	Email: alan.b.johnston@gmail.com		Email: alan.b.johnston@gmail.com
	Bernard Aboba		Bernard Aboba
	Microsoft		Microsoft
	One Microsoft Way		One Microsoft Way
	Redmond, WA 98052		Redmond, WA 98052
	USA		USA
	Email: bernard.aboba@gmail.com		Email: bernard.aboba@gmail.com
	Andrew Hutton		Andrew Hutton
	Atos		Atos
	Mid City Place		Mid City Place
	London WC1V 6EA		London WC1V 6EA
	UK		UK
	Email: andrew.hutton@atos.net		Email: andrew.hutton@atos.net
	Roland Jesske		Roland Jesske
	Deutsche Telekom		Deutsche Telekom
End of changes. 19 change blocks.
	27 lines changed or deleted		36 lines changed or added
This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/