draft-ietf-ippm-ipsec-09.txt		draft-ietf-ippm-ipsec-10.txt
	IPPM WG K. Pentikousis, Ed.		IPPM WG K. Pentikousis, Ed.
	Internet-Draft EICT		Internet-Draft EICT
	Intended status: Standards Track E. Zhang		Intended status: Standards Track E. Zhang
	Expires: August 15, 2015 Y. Cui		Expires: November 30, 2015 Y. Cui
	Huawei Technologies		Huawei Technologies
	February 11, 2015		May 29, 2015
	IKEv2-based Shared Secret Key for O/TWAMP		IKEv2-derived Shared Secret Key for O/TWAMP
	draft-ietf-ippm-ipsec-09		draft-ietf-ippm-ipsec-10
	Abstract		Abstract
	The One-way Active Measurement Protocol (OWAMP) and Two-Way Active		The One-way Active Measurement Protocol (OWAMP) and Two-Way Active
	Measurement Protocol (TWAMP) security mechanism require that both the		Measurement Protocol (TWAMP) security mechanisms require that both
	client and server endpoints possess a shared secret. Since the		the client and server endpoints possess a shared secret. This
	currently-standardized O/TWAMP security mechanism only supports a		document describes the use of keys derived from an IKEv2 security
	pre-shared key mode, large scale deployment of O/TWAMP is hindered		association (SA) as the shared key in O/TWAMP. If the shared key can
	significantly. At the same time, recent trends point to wider		be derived from the IKEv2 SA, O/TWAMP can support certificate-based
	Internet Key Exchange Protocol Version 2 (IKEv2) deployment which, in		key exchange, which would allow for more operational flexibility and
	turn, calls for mechanisms and methods that enable tunnel end-users,		efficiency. The key derivation presented in this document can also
	as well as operators, to measure one-way and two- way network		facilitate automatic key management.
	performance in a standardized manner. This document describes the
	use of keys derived from an IKEv2 security association (SA) as the
	shared key in O/TWAMP. If the shared key can be derived from the
	IKEv2 SA, O/TWAMP can support certificate-based key exchange, which
	would allow for more operational flexibility and efficiency. The key
	derivation presented in this document can also facilitate automatic
	key management.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 http://datatracker.ietf.org/drafts/current/.		Drafts is at http://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 August 15, 2015.		This Internet-Draft will expire on November 30, 2015.
	Copyright Notice		Copyright Notice
	Copyright (c) 2015 IETF Trust and the persons identified as the		Copyright (c) 2015 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
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://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
	skipping to change at page 2, line 32		skipping to change at page 2, line 23
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
	3. Scope and Applicability . . . . . . . . . . . . . . . . . . . 4		3. Scope and Applicability . . . . . . . . . . . . . . . . . . . 4
	4. O/TWAMP Security . . . . . . . . . . . . . . . . . . . . . . 4		4. O/TWAMP Security . . . . . . . . . . . . . . . . . . . . . . 4
	4.1. O/TWAMP-Control Security . . . . . . . . . . . . . . . . 5		4.1. O/TWAMP-Control Security . . . . . . . . . . . . . . . . 5
	4.2. O/TWAMP-Test Security . . . . . . . . . . . . . . . . . . 6		4.2. O/TWAMP-Test Security . . . . . . . . . . . . . . . . . . 6
	4.3. O/TWAMP Security Root . . . . . . . . . . . . . . . . . . 7		4.3. O/TWAMP Security Root . . . . . . . . . . . . . . . . . . 7
	5. O/TWAMP for IPsec Networks . . . . . . . . . . . . . . . . . 7		5. O/TWAMP for IPsec Networks . . . . . . . . . . . . . . . . . 7
	5.1. Shared Key Derivation . . . . . . . . . . . . . . . . . . 7		5.1. Shared Key Derivation . . . . . . . . . . . . . . . . . . 7
	5.2. Server Greeting Message Update . . . . . . . . . . . . . 8		5.2. Server Greeting Message Update . . . . . . . . . . . . . 8
	5.3. Set-Up-Response Update . . . . . . . . . . . . . . . . . 10		5.3. Set-Up-Response Update . . . . . . . . . . . . . . . . . 9
	5.4. O/TWAMP over an IPsec tunnel . . . . . . . . . . . . . . 11		5.4. O/TWAMP over an IPsec tunnel . . . . . . . . . . . . . . 11
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 11		6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
	8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12		8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
	9.1. Normative References . . . . . . . . . . . . . . . . . . 12		9.1. Normative References . . . . . . . . . . . . . . . . . . 12
	9.2. Informative References . . . . . . . . . . . . . . . . . 12		9.2. Informative References . . . . . . . . . . . . . . . . . 13
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
	1. Introduction		1. Introduction
	The One-way Active Measurement Protocol (OWAMP) [RFC4656] and the		The One-way Active Measurement Protocol (OWAMP) [RFC4656] and the
	Two-Way Active Measurement Protocol (TWAMP) [RFC5357] can be used to		Two-Way Active Measurement Protocol (TWAMP) [RFC5357] can be used to
	measure network performance parameters such as latency, bandwidth,		measure network performance parameters such as latency, bandwidth,
	and packet loss by sending probe packets and monitoring their		and packet loss by sending probe packets and monitoring their
	experience in the network. In order to guarantee the accuracy of		experience in the network. In order to guarantee the accuracy of
	network measurement results, security aspects must be considered.		network measurement results, security aspects must be considered.
	skipping to change at page 3, line 18		skipping to change at page 3, line 9
	[RFC5357] requires that endpoints (i.e. both the client and the		[RFC5357] requires that endpoints (i.e. both the client and the
	server) possess a shared secret. In today's network deployments,		server) possess a shared secret. In today's network deployments,
	however, the use of pre-shared keys is far from optimal. For		however, the use of pre-shared keys is far from optimal. For
	example, in wireless infrastructure networks, certain network		example, in wireless infrastructure networks, certain network
	elements, which can be seen as the two endpoints from an O/TWAMP		elements, which can be seen as the two endpoints from an O/TWAMP
	perspective, support certificate-based security. For instance,		perspective, support certificate-based security. For instance,
	consider the case in which one wants to measure IP performance		consider the case in which one wants to measure IP performance
	between a E-UTRAN Evolved Node B (eNB) and Security Gateway (SeGW).		between a E-UTRAN Evolved Node B (eNB) and Security Gateway (SeGW).
	Both eNB and SeGW are 3GPP Long Term Evolution (LTE) nodes and		Both eNB and SeGW are 3GPP Long Term Evolution (LTE) nodes and
	support certificate mode and the Internet Key Exchange Protocol		support certificate mode and the Internet Key Exchange Protocol
	Version 2 (IKEv2). Since the currently standardized O/TWAMP security		Version 2 (IKEv2).
	mechanism only supports pre-shared key mode, large scale deployment
	of O/TWAMP is hindered significantly. Furthermore, deployment and
	management of "shared secrets" for massive equipment installation
	consumes a tremendous amount of effort and is prone to human error.
	With IKEv2 widely used, employing keys derived from IKEv2 security		The O/TWAMP security mechanism specified in [RFC4656] [RFC5357] only
	association (SA) as shared key can be considered as a viable		supports the pre-shared key mode hindering large scale deployment of
	alternative. In mobile telecommunication networks, the deployment		O/TWAMP. Furthermore, deployment and management of "shared secrets"
	rate of IPsec exceeds 95% with respect to the LTE serving network.		for massive equipment installation consumes a tremendous amount of
	In older-technology cellular networks, such as UMTS and GSM, IPsec		effort and is prone to human error. At the same time, recent trends
	use penetration is lower, but still quite significant. If the shared		point to wider Internet Key Exchange Protocol Version 2 (IKEv2)
	key can be derived from the IKEv2 SA, O/TWAMP can support cert-based		deployment which, in turn, calls for mechanisms and methods that
			enable tunnel end-users, as well as operators, to measure one-way and
			two-way network performance in a standardized manner.
			With IKEv2 widely deployed, employing shared keys derived from IKEv2
			security association (SA) can be considered as a viable alternative
			through the method described in this document. If the shared key can
			be derived from the IKEv2 SA, O/TWAMP can support certificate-based
	key exchange and practically increase operational flexibility and		key exchange and practically increase operational flexibility and
	efficiency. The use of IKEv2 also makes it easier to extend		efficiency. The use of IKEv2 also makes it easier to extend
	automatic key management. In general, O/TWAMP measurement packets		automatic key management.
	can be transmitted inside the IPsec tunnel, as it occurs with typical
	user traffic, or transmitted outside the IPsec tunnel. This may
	depend on the operator's policy and is orthogonal to the mechanism
	described in this document.
	When IPsec is deployed, protecting O/TWAMP traffic in unauthenticated		In general, O/TWAMP measurement packets can be transmitted inside the
	mode using IPsec is one option. Another option is to protect O/TWAMP		IPsec tunnel, as it occurs with typical user traffic, or transmitted
	traffic using O/TWAMP layer security established using the PSK		outside the IPsec tunnel. This may depend on the operator's policy
			and the performance evaluation goal, and is orthogonal to the
			mechanism described in this document. When IPsec is deployed,
			protecting O/TWAMP traffic in unauthenticated mode using IPsec is one
			option. Another option is to protect O/TWAMP traffic using the O/
			TWAMP layer security established using the Pre-Shared Key (PSK)
	derived from IKEv2 but bypassing the IPsec tunnel. Protecting		derived from IKEv2 but bypassing the IPsec tunnel. Protecting
	unauthenticated O/TWAMP control and/or test traffic via		unauthenticated O/TWAMP control and/or test traffic via
	Authentication Header (AH) [RFC4302] or Encapsulating Security		Authentication Header (AH) [RFC4302] or Encapsulating Security
	Payload (ESP) [RFC4303] cannot provide various security options,		Payload (ESP) [RFC4303] cannot provide various security options,
	e.g. it cannot authenticate part of a O/TWAMP packet as mentioned in		e.g. it cannot authenticate part of a O/TWAMP packet as mentioned in
	[RFC4656]. For measuring latency, timestamp is carried in O/TWAMP		[RFC4656].
			For measuring latency, a timestamp is carried in O/TWAMP test
	traffic. The sender has to fetch the timestamp, encrypt it, and send		traffic. The sender has to fetch the timestamp, encrypt it, and send
	it. In this case, the middle step can be skipped, potentially		it. When the mechanism described in this document is used, partial
	improving accuracy as the sequence number can be encrypted and		authentication of O/TWAMP packets is possible and therefore the
	authenticated before the timestamp is fetched. It is the same case		middle step can be skipped, potentially improving accuracy as the
	for the receiver since it can obtain the timestamp by skipping the		sequence number can be encrypted and authenticated before the
	decryption step. In such cases, protecting O/TWAMP traffic using O/		timestamp is fetched. The receiver obtains the timestamp without the
	TWAMP layer security but bypassing IPsec tunnel has its advantages.		need for the corresponding decryption step. In such cases,
			protecting O/TWAMP traffic using O/TWAMP layer security but bypassing
			the IPsec tunnel has its advantages.
	This document specifies a method for enabling network measurements		This document specifies a method for enabling network measurements
	between a TWAMP client and a TWAMP server, as discussed in Section 3.		between a TWAMP client and a TWAMP server, as discussed in Section 3.
	In short, the shared key used for securing TWAMP traffic is derived		In short, the shared key used for securing TWAMP traffic is derived
	using IKEv2 [RFC7296]. From an operations and management perspective		from IKEv2 [RFC7296]. From an operations and management perspective
	[RFC5706], the mechanism described in this document requires that		[RFC5706], the mechanism described in this document requires that
	both the TWAMP client and server support IPsec. This method SHOULD		both the TWAMP Control-Client and Server support IPsec.
	be used when O/TWAMP traffic is bypassing IPsec protection and is		IKEv2-derived keys SHOULD be used instead of shared secrets when O/
	running over an external network exactly between two IKEv2 systems.		TWAMP is employed in a deployment using IKEv2.
	After clarifying the terminology and scope in the subsequent		After clarifying the terminology and scope in the subsequent
	sections, the remainder of this document is organized as follows.		sections, the remainder of this document is organized as follows.
	Section 4 summarizes O/TWAMP protocol operation with respect to		Section 4 summarizes O/TWAMP protocol operation with respect to
	security. Section 5 presents the method for binding TWAMP and IKEv2		security. Section 5 presents the method for binding TWAMP and IKEv2
	for network measurements between the client and the server which both		for network measurements between the client and the server which both
	support IKEv2. Finally, Section 6 discusses the security		support IKEv2. Finally, Section 6 discusses the security
	considerations arising from the proposed mechanisms.		considerations arising from the proposed mechanisms.
	2. Terminology		2. Terminology
	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 [RFC2119].		document are to be interpreted as described in [RFC2119].
	3. Scope and Applicability		3. Scope and Applicability
	This document reserves from the TWAMP-Modes registry the Mode value		TWAMP implementations signal the use of this method by setting
	IKEv2Derived which is equal to 128 (i.e. bit set in position 7) and		IKEv2Derived (see Section 7)
	MUST be used by TWAMP implementations compatible with this
	specification.
	Although the control procedures described in this document are		Although the control procedures described in this document are
	applicable to OWAMP per se, the lack of an established IANA registry		applicable to OWAMP per se, the lack of an established IANA registry
	for OWAMP Mode values technically prevents us from extending OWAMP		for OWAMP Mode values akin to that listed in Section 7 technically
	Mode values. Therefore, independent OWAMP implementations SHOULD be		prevents us from extending OWAMP Mode values. Therefore, independent
	checked for full compatibility with respect to the use of this Mode		OWAMP implementations SHOULD be checked for full compatibility with
	value. Until an IANA registry for OWAMP Mode values is established,		respect to the use of this Mode value. Until an IANA registry for
	the use this feature in OWAMP implementations MUST be arranged		OWAMP Mode values is established, the use of this feature in OWAMP
	privately among consenting OWAMP users.		implementations MUST be arranged privately among consenting OWAMP
			users.
	4. O/TWAMP Security		4. O/TWAMP Security
	Security for O/TWAMP-Control and O/TWAMP-Test are briefly reviewed in		Security for O/TWAMP-Control and O/TWAMP-Test are briefly reviewed in
	the following subsections.		the following subsections.
	4.1. O/TWAMP-Control Security		4.1. O/TWAMP-Control Security
	O/TWAMP uses a simple cryptographic protocol which relies on		O/TWAMP uses a simple cryptographic protocol which relies on
	o AES in Cipher Block Chaining (AES-CBC) for confidentiality		o Advanced Encryption Standard (AES) in Cipher Block Chaining (AES-
			CBC) for confidentiality
	o HMAC-SHA1 truncated to 128 bits for message authentication		o Hash-based Message Authentication Code (HMAC)-Secure Hash
			Algorithm1 (SHA1) truncated to 128 bits for message authentication
	Three modes of operation are supported in the OWAMP-Control protocol:		Three modes of operation are supported in the OWAMP-Control protocol:
	unauthenticated, authenticated, and encrypted. In addition to these		unauthenticated, authenticated, and encrypted. In addition to these
	modes, the TWAMP-Control protocol also supports a mixed mode, i.e.		modes, the TWAMP-Control protocol also supports a mixed mode, i.e.
	the TWAMP-Control protocol operates in encrypted mode while TWAMP-		the TWAMP-Control protocol operates in encrypted mode while TWAMP-
	Test protocol operates in unauthenticated mode. The authenticated,		Test protocol operates in unauthenticated mode. The authenticated,
	encrypted and mixed modes require that endpoints possess a shared		encrypted and mixed modes require that endpoints possess a shared
	secret, typically a passphrase. The secret key is derived from the		secret, typically a passphrase. The secret key is derived from the
	passphrase using a password-based key derivation function PBKDF2		passphrase using a password-based key derivation function PBKDF2
	(PKCS#5) [RFC2898].		(PKCS#5) [RFC2898].
	In the unauthenticated mode, the security parameters are left unused.		In the unauthenticated mode, the security parameters are left unused.
	In the authenticated, encrypted and mixed modes, the security		In the authenticated, encrypted and mixed modes, the security
	parameters are negotiated during the control connection		parameters are negotiated during the control connection
	establishment.		establishment.
	Figure 1 illustrates the initiation stage of the O/TWAMP-Control		Figure 1 illustrates the initiation stage of the O/TWAMP-Control
	protocol between a client and the server. In short, the client opens		protocol between a Control-Client and a Server. In short, the
	a TCP connection to the server in order to be able to send O/TWAMP-		Control-Client opens a TCP connection to the Server in order to be
	Control commands. The server responds with a Server Greeting, which		able to send O/TWAMP-Control commands. The Server responds with a
	contains the Modes, Challenge, Salt, Count, and MBZ fields (see		Server Greeting, which contains the Modes, Challenge, Salt, Count,
	Section 3.1 of [RFC4656]). If the client-preferred mode is		and MBZ fields (see Section 3.1 of [RFC4656]). If the Control-Client
	available, the client responds with a Set-Up- Response message,		preferred mode is available, the client responds with a Set-Up-
	wherein the selected Mode, as well as the KeyID, Token and Client		Response message, wherein the selected Mode, as well as the KeyID,
	initialization vector (IV) are included. The Token is the		Token and Client initialization vector (IV) are included. The Token
	concatenation of a 16-octet Challenge, a 16-octet AES Session-key		is the concatenation of a 16-octet Challenge, a 16-octet AES Session-
	used for encryption, and a 32-octet HMAC-SHA1 Session-key used for		key used for encryption, and a 32-octet HMAC-SHA1 Session-key used
	authentication. The Token is encrypted using AES-CBC.		for authentication. The Token is encrypted using AES-CBC.
	+--------+ +--------+		+----------------+ +--------+
	| Client | | Server |		| Control-Client | | Server |
	+--------+ +--------+		+----------------+ +--------+
	| |		| |
	|<---- TCP Connection ----->|		|<------ TCP Connection-- ----->|
	| |		| |
	|<---- Greeting message ----|		|<------ Greeting message ------|
	| |		| |
	|----- Set-Up-Response ---->|		|------- Set-Up-Response ------>|
	| |		| |
	|<---- Server-Start --------|		|<------ Server-Start ----------|
	| |		| |
	Figure 1: Initiation of O/TWAMP-Control		Figure 1: Initiation of O/TWAMP-Control
	Encryption uses a key derived from the shared secret associated with		Encryption uses a key derived from the shared secret associated with
	KeyID. In the authenticated, encrypted and mixed modes, all further		KeyID. In the authenticated, encrypted and mixed modes, all further
	communication is encrypted using the AES Session-key and		communication is encrypted using the AES Session-key and
	authenticated with the HMAC Session-key. After receiving Set-Up-		authenticated with the HMAC Session-key. After receiving the Set-Up-
	Response the server responds with a Server-Start message containing		Response the Server responds with a Server-Start message containing
	Server-IV. The client encrypts everything it transmits through the		the Server-IV. The Control-Client encrypts everything it transmits
	just-established O/TWAMP-Control connection using stream encryption		through the just-established O/TWAMP-Control connection using stream
	with Client- IV as the IV. Correspondingly, the server encrypts its		encryption with Client- IV as the IV. Correspondingly, the Server
	side of the connection using Server-IV as the IV. The IVs themselves		encrypts its side of the connection using Server-IV as the IV. The
	are transmitted in cleartext. Encryption starts with the block		IVs themselves are transmitted in cleartext. Encryption starts with
	immediately following that containing the IV.		the block immediately following that containing the IV.
	The AES Session-key and HMAC Session-key are generated randomly by		The AES Session-key and HMAC Session-key are generated randomly by
	the client. The HMAC Session-key is communicated along with the AES		the Control-Client. The HMAC Session-key is communicated along with
	Session-key during O/TWAMP-Control connection setup. The HMAC		the AES Session-key during O/TWAMP-Control connection setup. The
	Session-key is derived independently of the AES Session-key.		HMAC Session-key is derived independently of the AES Session-key.
	4.2. O/TWAMP-Test Security		4.2. O/TWAMP-Test Security
	The O/TWAMP-Test protocol runs over UDP, using the client and server		The O/TWAMP-Test protocol runs over UDP, using the Session-Sender and
	IP and port numbers that were negotiated during the Request-Session		Session-Reflector IP and port numbers that were negotiated during the
	exchange. O/TWAMP- Test has the same mode with O/TWAMP-Control and		Request-Session exchange. O/TWAMP- Test has the same mode with O/
	all O/TWAMP-Test sessions inherit the corresponding O/TWAMP-Control		TWAMP-Control and all O/TWAMP-Test sessions inherit the corresponding
	session mode except when operating in mixed mode.		O/TWAMP-Control session mode except when operating in mixed mode.
	The O/TWAMP-Test packet format is the same in authenticated and		The O/TWAMP-Test packet format is the same in authenticated and
	encrypted modes. The encryption and authentication operations are,		encrypted modes. The encryption and authentication operations are,
	however, different. Similarly with the respective O/TWAMP-Control		however, different. Similarly with the respective O/TWAMP-Control
	session, each O/TWAMP-Test session has two keys: an AES Session-key		session, each O/TWAMP-Test session has two keys: an AES Session-key
	and an HMAC Session-key. However, there is a difference in how the		and an HMAC Session-key. However, there is a difference in how the
	keys are obtained:		keys are obtained:
	O/TWAMP-Control: the keys are generated by the client and		O/TWAMP-Control: the keys are generated by the Control-Client and
	communicated to the server during the control connection		communicated to the Server during the control connection
	establishment with the Set-Up-Response message (as part of		establishment with the Set-Up-Response message (as part of
	the Token).		the Token).
	O/TWAMP-Test: the keys are derived from the O/TWAMP-Control keys and		O/TWAMP-Test: the keys are derived from the O/TWAMP-Control keys and
	the session identifier (SID), which serve as inputs of the		the session identifier (SID), which serve as inputs of the
	key derivation function (KDF). The O/TWAMP-Test AES Session-		key derivation function (KDF). The O/TWAMP-Test AES Session-
	key is generated using the O/TWAMP- Control AES Session-key,		key is generated using the O/TWAMP- Control AES Session-key,
	with the 16-octet session identifier (SID), for encrypting		with the 16-octet session identifier (SID), for encrypting
	and decrypting the packets of the particular O/TWAMP-Test		and decrypting the packets of the particular O/TWAMP-Test
	session. The O/TWAMP-Test HMAC Session-key is generated		session. The O/TWAMP-Test HMAC Session-key is generated
	using the O/TWAMP-Control HMAC Session-key, with the 16-octet		using the O/TWAMP-Control HMAC Session-key, with the 16-octet
	session identifier (SID), for authenticating the packets of		session identifier (SID), for authenticating the packets of
	the particular O/TWAMP-Test session.		the particular O/TWAMP-Test session.
	4.3. O/TWAMP Security Root		4.3. O/TWAMP Security Root
	As discussed above, the AES Session-key and HMAC Session-key used by		As discussed above, the AES Session-key and HMAC Session-key used by
	the O/TWAMP-Test protocol are derived from the AES Session-key and		the O/TWAMP-Test protocol are derived from the AES Session-key and
	HMAC Session-key which are used in O/TWAMP-Control protocol. The AES		HMAC Session-key which are used in the O/TWAMP-Control protocol. The
	Session-key and HMAC Session-key used in the O/TWAMP-Control protocol		AES Session-key and HMAC Session-key used in the O/TWAMP-Control
	are generated randomly by the client, and encrypted with the shared		protocol are generated randomly by the Control-Client, and encrypted
	secret associated with KeyID. Therefore, the security root is the		with the shared secret associated with KeyID. Therefore, the
	shared secret key. Thus, for large deployments, key provision and		security root is the shared secret key. Thus, for large deployments,
	management may become overly complicated. Comparatively, a		key provision and management may become overly complicated.
	certificate-based approach using IKEv2 can automatically manage the		Comparatively, a certificate-based approach using IKEv2 can
	security root and solve this problem, as we explain in Section 5.		automatically manage the security root and solve this problem, as we
			explain in Section 5.
	5. O/TWAMP for IPsec Networks		5. O/TWAMP for IPsec Networks
	This section presents a method of binding O/TWAMP and IKEv2 for		This section presents a method of binding O/TWAMP and IKEv2 for
	network measurements between a client and a server which both support		network measurements between a client and a server which both support
	IPsec. In short, the shared key used for securing O/TWAMP traffic is		IPsec. In short, the shared key used for securing O/TWAMP traffic is
	derived using IKEv2 [RFC7296].		derived using IKEv2 [RFC7296].
	5.1. Shared Key Derivation		5.1. Shared Key Derivation
	In the authenticated, encrypted and mixed modes, the shared secret		In the authenticated, encrypted and mixed modes, the shared secret
	key MUST be derived from the IKEv2 Security Association (SA). Note		key MUST be derived from the IKEv2 Security Association (SA). Note
	that we explicitly opt to derive the shared secret key from the IKEv2		that we explicitly opt to derive the shared secret key from the IKEv2
	SA, rather than the child SA, since the use case whereby an IKEv2 SA		SA, rather than the child SA, since the use case whereby an IKEv2 SA
	can be created without generating any child SA is possible [RFC6023].		can be created without generating any child SA is possible [RFC6023].
	When the shared secret key is derived from the IKEv2 SA, SK_d must be		When the shared secret key is derived from the IKEv2 SA, SK_d must be
	generated first. SK_d MUST be computed as per [RFC7296].		generated first. SK_d must be computed as per [RFC7296].
	The shared secret key MUST be generated as follows:		The shared secret key MUST be generated as follows:
	Shared secret key = prf( SK_d, "IPPM" )		Shared secret key = prf( SK_d, "IPPM" )
	Wherein the string "IPPM" comprises four ASCII characters and "prf"		Wherein the string "IPPM" is encoded in ASCII and "prf" is a
	is a pseudorandom function. It is recommended that the shared secret		pseudorandom function.
	key is derived in the IPsec layer. This way, the IPsec keying
	material is not exposed to the O/TWAMP client. Note, however, that		It is recommended that the shared secret key is derived in the IPsec
	the interaction between the O/TWAMP and IPsec layers is host-internal		layer so that IPsec keying material is not exposed to the O/TWAMP
	and implementation-specific. Therefore, this is clearly outside the		client. Note, however, that the interaction between the O/TWAMP and
	scope of this document, which focuses on the interaction between the		IPsec layers is host-internal and implementation-specific.
	O/TWAMP client and server. That said, one possible way could be the		Therefore, this is clearly outside the scope of this document, which
	following: at the client side, the IPSec layer can perform a lookup		focuses on the interaction between the O/TWAMP client and server.
	in the Security Association Database (SAD) using the IP address of		That said, one possible way could be the following: at the Control-
	the server and thus match the corresponding IKEv2 SA. At the server		Client side, the IPSec layer can perform a lookup in the Security
	side, the IPSec layer can look up the corresponding IKEv2 SA by using		Association Database (SAD) using the IP address of the Server and
	the SPIs sent by the client, and therefore extract the shared secret		thus match the corresponding IKEv2 SA. At the Server side, the IPSec
	key. In case that both client and server do support IKEv2 but there		layer can look up the corresponding IKEv2 SA by using the Security
	is no current IKEv2 SA, two alternative ways could be considered.		Parameter Indexes (SPIs) sent by the Control-Client (see
	First, the O/TWAMP client initiates the establishment of the IKEv2		Section 5.3), and therefore extract the shared secret key.
			In case that both client and server do support IKEv2 but there is no
			current IKEv2 SA, two alternative ways could be considered. First,
			the O/TWAMP Control-Client initiates the establishment of the IKEv2
	SA, logs this operation, and selects the mode which supports IKEv2.		SA, logs this operation, and selects the mode which supports IKEv2.
	Alternatively, the O/TWAMP client does not initiate the establishment		Alternatively, the O/TWAMP Control-Client does not initiate the
	of the IKEv2 SA, logs an error for operational management purposes,		establishment of the IKEv2 SA, logs an error for operational
	and proceeds with the modes defined in [RFC4656][RFC5357][RFC5618].		management purposes, and proceeds with the modes defined in
	Again, although both alternatives are feasible, they are in fact		[RFC4656][RFC5357][RFC5618]. Again, although both alternatives are
	implementation-specific.		feasible, they are in fact implementation-specific.
	If rekeying for the IKEv2 SA or deletion of the IKEv2 SA occurs, the		If rekeying for the IKEv2 SA or deletion of the IKEv2 SA occurs, the
	corresponding shared secret key generated from the SA can continue to		corresponding shared secret key generated from the SA MUST continue
	be used until the O/TWAMP session terminates.		to be used until the O/TWAMP session terminates.
	5.2. Server Greeting Message Update		5.2. Server Greeting Message Update
	To achieve a binding association between the key generated from IKEv2		To trigger a binding association between the key generated from IKEv2
	and the O/TWAMP shared secret key, Server Greeting Message should		and the O/TWAMP shared secret key, the Modes field in the Server
	include these extensions, as in Figure 2.		Greeting Message (Figure 2) will need to allow for support of key
			derivation as discussed in Section 5.1. Therefore, when this method
			is used, the Modes value extension MUST be supported. Support for
			deriving the shared key from the IKEv2 SA is indicated by setting
			IKEv2Derived (see Section 7).
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	| Unused (12 octets) |		| Unused (12 octets) |
	| |		| |
	|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Modes |		| Modes |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 9, line 33		skipping to change at page 9, line 33
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Count (4 octets) |		| Count (4 octets) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	| MBZ (12 octets) |		| MBZ (12 octets) |
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 2: Server Greeting format		Figure 2: Server Greeting format
	The Modes field in Figure 2 will need to allow for support of key
	derivation as discussed in Section 5.1. As such, the Modes value
	extension MUST be supported by implementations compatible with this
	document, indicating support for deriving the shared key from the
	IKEv2 SA. The new Modes value indicating support for this
	specification is IKEv2Derived and is equal to 128 (i.e. bit set in
	position 7). Clearly, an implementation compatible with this
	specification MUST support the authenticated, encrypted and mixed
	modes as per [RFC4656][RFC5357][RFC5618].
	The choice of this set of Modes values poses no backwards		The choice of this set of Modes values poses no backwards
	compatibility problems to existing O/TWAMP clients. Robust legacy		compatibility problems to existing O/TWAMP clients. Robust legacy
	client implementations would disregard the fact that the IKEv2Derived		Control-Client implementations would disregard the fact that the
	Modes bit in the Server Greeting is set. On the other hand, a client		IKEv2Derived Modes bit in the Server Greeting is set. On the other
	compatible with this specification can easily identify that the O/		hand, a Control-Client implementing this method can identify that the
	TWAMP server contacted does not support this specification. If the		O/TWAMP Server contacted does not support this specification. If the
	server supports other Modes, as one could assume, the client would		Server supports other Modes, as one could assume, the Control-Client
	then decide which Mode to use and indicate such accordingly as per		would then decide which Mode to use and indicate such accordingly as
	[RFC4656][RFC5357]. A client compatible with this specification		per [RFC4656][RFC5357]. A Control-Client implementing this method
	which decides not to employ IKEv2 derivation, can simply behave as a		which decides not to employ IKEv2 derivation, can simply behave as a
	purely [RFC4656]/[RFC5357] compatible client.		purely [RFC4656]/[RFC5357] compatible client.
	5.3. Set-Up-Response Update		5.3. Set-Up-Response Update
	The Set-Up-Response Message should be updated as in Figure 3. When a		The Set-Up-Response Message Figure 3 is updated as follows. When a
	O/TWAMP client compatible with this specification receives a Server		O/TWAMP Control-Client implementing this method receives a Server
	Greeting indicating support for Mode IKEv2Derived it SHOULD reply to		Greeting indicating support for Mode IKEv2Derived it SHOULD reply to
	the O/TWAMP server with a Set-Up response that indicates so. For		the O/TWAMP Server with a Set-Up response that indicates so. For
	example, a compatible O/TWAMP client choosing the authenticated mode		example, a compatible O/TWAMP Control-Client choosing the
	with IKEv2 shared secret key derivation should set Mode to 130, i.e.		authenticated mode with IKEv2 shared secret key derivation should set
	set the bits in positions 1 and 7 to one.		Mode to 130, i.e. set the bits in positions 1 and 7 to one (see
			Section 7).
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Mode |		| Mode |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	| Key ID (80 octets) |		| Key ID (80 octets) |
	| |		| |
	| |		| |
	skipping to change at page 10, line 39		skipping to change at page 10, line 29
	| |		| |
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| |		| |
	| Client-IV (12 octets) |		| Client-IV (12 octets) |
	| |		| |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 3: Set-Up-Response Message		Figure 3: Set-Up-Response Message
	The Security Parameter Index (SPI)(see [RFC4301] [RFC7296]) can		The Security Parameter Index (SPI)(see [RFC4301] [RFC7296]) uniquely
	uniquely identify the Security Association (SA). If the client		identifies the Security Association (SA). If the Control-Client
	supports the derivation of shared secret key from IKEv2 SA, it will		supports the derivation of shared secret key from IKEv2 SA, it will
	choose the corresponding mode value and carry SPIi and SPIr in the		choose the corresponding mode value and carry SPIi and SPIr in the
	Key ID field. SPIi and SPIr MUST be included in the Key ID field of		Key ID field. SPIi and SPIr MUST be included in the Key ID field of
	Set-Up-Response Message to indicate the IKEv2 SA from which the O/		the Set-Up-Response Message to indicate the IKEv2 SA from which the
	TWAMP shared secret key derived from. The length of SPI is 8 octets.		O/TWAMP shared secret key derived from. The length of SPI is 8
	Therefore, the first 8 octets of Key ID field MUST carry SPIi and the		octets. Therefore, the first 8 octets of Key ID field MUST carry
	second 8 octets MUST carry SPIr. The remaining bits of the Key ID		SPIi and the second 8 octets MUST carry SPIr. The remaining bits of
	field MUST set to zero.		the Key ID field MUST be set to zero.
	A O/TWAMP server which supports the specification of this document,		A O/TWAMP Server implementation of this method, MUST obtain the SPIi
	MUST obtain the SPIi and SPIr from the first 16 octets and ignore the		and SPIr from the first 16 octets and ignore the remaining octets of
	remaining octets of the Key ID field. Then, the client and the		the Key ID field. Then, the Control-Client and the Server can derive
	server can derive the shared secret key based on the mode value and		the shared secret key based on the Mode value and SPI. If the O/
	SPI. If the O/TWAMP server cannot find the IKEv2 SA corresponding to		TWAMP Server cannot find the IKEv2 SA corresponding to the SPIi and
	the SPIi and SPIr received, it MUST log the event for operational		SPIr received, it MUST log the event for operational management
	management purposes. In addition, the O/TWAMP server SHOULD set the		purposes. In addition, the O/TWAMP Server SHOULD set the Accept
	Accept field of the Server-Start message to the value 6 to indicate		field of the Server-Start message to the value 6 to indicate that the
	that server is not willing to conduct further transactions in this O/		Server is not willing to conduct further transactions in this O/
	TWAMP-Control session since it can not find the corresponding IKEv2		TWAMP-Control session since it can not find the corresponding IKEv2
	SA.		SA.
	5.4. O/TWAMP over an IPsec tunnel		5.4. O/TWAMP over an IPsec tunnel
	IPsec Authentication Header (AH) [RFC4302] and Encapsulating Security		IPsec Authentication Header (AH) [RFC4302] and Encapsulating Security
	Payload (ESP) [RFC4303] provide confidentiality and data integrity to		Payload (ESP) [RFC4303] provide confidentiality and data integrity to
	IP datagrams. An IPsec tunnel can be used to provide the protection		IP datagrams. An IPsec tunnel can be used to provide the protection
	needed for O/TWAMP Control and Test packets, even if the peers choose		needed for O/TWAMP Control and Test packets, even if the peers choose
	the unauthenticated mode of operation. In order to ensure		the unauthenticated mode of operation. In order to ensure
	authenticity and security, the IPsec tunnel SHOULD be configured to		authenticity and security, O/TWAMP packets between two IKEv2 systems
	include O/TWAMP measurement packets even when using the		SHOULD be configured to use the corresponding IPsec tunnel running
	unauthenticated mode.		over an external network even when using the O/TWAMP unauthenticated
			mode.
	6. Security Considerations		6. Security Considerations
	As the shared secret key is derived from the IKEv2 SA, the key		As the shared secret key is derived from the IKEv2 SA, the key
	derivation algorithm strength and limitations are as per [RFC7296].		derivation algorithm strength and limitations are as per [RFC7296].
	The strength of a key derived from a Diffie-Hellman exchange using		The strength of a key derived from a Diffie-Hellman exchange using
	any of the groups defined here depends on the inherent strength of		any of the groups defined here depends on the inherent strength of
	the group, the size of the exponent used, and the entropy provided by		the group, the size of the exponent used, and the entropy provided by
	the random number generator employed. The strength of all keys and		the random number generator employed. The strength of all keys and
	implementation vulnerabilities, particularly Denial of Service (DoS)		implementation vulnerabilities, particularly Denial of Service (DoS)
	attacks are as defined in [RFC7296].		attacks are as defined in [RFC7296].
	7. IANA Considerations		7. IANA Considerations
	IANA is requested to allocate the IKEv2Derived Mode bit that is equal		During the production of this document, the authors and reviewers
	to 128 (i.e. bit set in position 7) in the TWAMP-Modes registry. The		noticed that the TWAMP-Modes registry, which should describe a
	TWAMP-Modes registry should be augmented as follows:		bitfield of flags, instead is defined as a registry of integer
			values. In addition, the Semantics Definition column seems to have
			spurious information in it. The registry should be changed to
			correct these issues, as follows:
	Value Description Semantics Definition		Bit|Description |Semantics |Reference|
	--------------------------------------------------------		| |Definition | |
	128 IKEv2 Derived This memo, Section 5.2		---|-------------------------------------------|------------|---------|
	Mode Capability new bit position 7		0 Unauthenticated Section 3.1 [RFC4656]
			1 Authenticated Section 3.1 [RFC4656]
			2 Encrypted Section 3.1 [RFC4656]
			3 Unauth.TEST protocol,Encrypted CONTROL Section 3.1 [RFC5618]
			4 Individual Session Control [RFC5938]
			5 Reflect Octets Capability [RFC6038]
			6 Symmetrical Size Sender Test Packet Format [RFC6038]
	Figure 4: IKEv2 Modes Capability		Figure 4: TWAMP Modes registry
			In addition, this document adds a new entry to this registry:
			Bit|Description |Semantics |Reference|
			| |Definition | |
			---|-------------------------------------------|------------|---------|
			7 IKEv2Derived Mode Capability Section 5 [RFCxxxx]
			(where RFCxxxx refers to draft-ietf-ippm-ipsec).
			Figure 5: IKEv2 Derived Mode Capability
	8. Acknowledgments		8. Acknowledgments
	We thank Eric Chen, Yaakov Stein, Brian Trammell, Emily Bi, John		We thank Eric Chen, Yaakov Stein, Brian Trammell, Emily Bi, John
	Mattsson, Steve Baillargeon, Spencer Dawkins, Tero Kivinen, Fred		Mattsson, Steve Baillargeon, Spencer Dawkins, Tero Kivinen, Fred
	Baker, Meral Shirazipour, and Hannes Tschofenig for their reviews,		Baker, Meral Shirazipour, Hannes Tschofenig, Ben Campbell, Stephen
	comments and text suggestions.		Farrell, Brian Haberman, and Barry Leiba for their reviews, comments
			and text suggestions.
	Al Morton deserves a special mention for his thorough reviews and		Al Morton deserves a special mention for his thorough reviews and
	text contributions to this document as well as the constructive		text contributions to this document as well as the constructive
	discussions over several IPPM meetings.		discussions over several IPPM meetings.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
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