< draft-ietf-dime-e2e-sec-req-03.txt		draft-ietf-dime-e2e-sec-req-04.txt >
	DIME H. Tschofenig		DIME H. Tschofenig
	Internet-Draft ARM Limited		Internet-Draft ARM Limited
	Intended status: Informational J. Korhonen, Ed.		Intended status: Informational J. Korhonen, Ed.
	Expires: December 19, 2015 Broadcom Corporation		Expires: July 16, 2016 Broadcom Corporation
	G. Zorn		G. Zorn
	Network Zen		Network Zen
	K. Pillay		K. Pillay
	Oracle Communications		Oracle Communications
	June 17, 2015		January 13, 2016
	Diameter AVP Level Security End-to-End Security: Scenarios and		Diameter AVP Level Security End-to-End Security: Scenarios and
	Requirements		Requirements
	draft-ietf-dime-e2e-sec-req-03.txt		draft-ietf-dime-e2e-sec-req-04.txt
	Abstract		Abstract
	This specification discusses requirements for providing Diameter		This specification discusses requirements for providing Diameter
	security at the level of individual Attribute Value Pairs.		security at the level of individual Attribute-Value Pairs.
	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 December 19, 2015.		This Internet-Draft will expire on July 16, 2016.
	Copyright Notice		Copyright Notice
	Copyright (c) 2015 IETF Trust and the persons identified as the		Copyright (c) 2016 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
	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 20 ¶		skipping to change at page 2, line 20 ¶
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Security Threats . . . . . . . . . . . . . . . . . . . . . . 3		3. Security Threats . . . . . . . . . . . . . . . . . . . . . . 3
	4. Scenarios for Diameter AVP-Level Protection . . . . . . . . . 5		4. Scenarios for Diameter AVP-Level Protection . . . . . . . . . 5
	5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7		5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 8		6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
	8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8		8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
	9.1. Normative References . . . . . . . . . . . . . . . . . . 8		9.1. Normative References . . . . . . . . . . . . . . . . . . 8
	9.2. Informative References . . . . . . . . . . . . . . . . . 8		9.2. Informative References . . . . . . . . . . . . . . . . . 9
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
	1. Introduction		1. Introduction
	The Diameter Base specification [2] offers security protection		The Diameter base protocol specification [2] offers security
	between neighboring Diameter peers and mandates that either TLS (for		protection between neighboring Diameter peers and mandates that peer
	TCP), DTLS (for SCTP), or IPsec is used. These security protocols		connections must be protected by TLS (for TCP), DTLS (for SCTP) or
	offer a wide range of security properties, including entity		alternative security mechanisms independent of Diameter (e.g., IPsec)
	authentication, data-origin authentication, integrity,		is used. These security protocols offer a wide range of security
	confidentiality protection and replay protection. They also support		properties, including entity authentication, data-origin
	a large number of cryptographic algorithms, algorithm negotiation,		authentication, integrity, confidentiality protection and replay
	and different types of credentials.		protection. They also support a large number of cryptographic
			algorithms, algorithm negotiation, and different types of
			credentials. It should be understood that TLS/DTLS/IPsec in Diameter
			context does not provide end-to-end security unless the Diameter
			nodes are direct peers i.e., neighboring Diameter nodes. The current
			Diameter security is realized hop-by-hop.
	The need to also offer additional security protection of AVPs between		The need to also offer additional security protection of AVPs between
	non-neighboring Diameter nodes was recognized very early in the work		non-neighboring Diameter nodes was recognized very early in the work
	on Diameter. This led to work on Diameter security using the		on Diameter. This led to work on Diameter security using the
	Cryptographic Message Syntax (CMS) [3]. Due to lack of deployment		Cryptographic Message Syntax (CMS) [3]. Due to lack of deployment
	interest at that time (and the complexity of the developed solution)		interest at that time (and the complexity of the developed solution)
	the specification was, however, never completed.		the specification was, however, never completed.
	In the meanwhile Diameter had received a lot of deployment interest		In the meanwhile Diameter had received a lot of deployment interest
	from the cellular operator community and because of the		from the cellular operator community and because of the
	skipping to change at page 3, line 22 ¶		skipping to change at page 3, line 27 ¶
	specification [2].		specification [2].
	In the figures below we use the symbols 'AVP' and '{AVP}k'. AVP		In the figures below we use the symbols 'AVP' and '{AVP}k'. AVP
	refers to an unprotected AVP and {AVP}k refers to an AVP that		refers to an unprotected AVP and {AVP}k refers to an AVP that
	experiences security protection (using key "k") without further		experiences security protection (using key "k") without further
	distinguishing between integrity and confidentiality protection.		distinguishing between integrity and confidentiality protection.
	3. Security Threats		3. Security Threats
	The following description aims to illustrate various security threats		The following description aims to illustrate various security threats
	that raise the need for protecting Diameter Attribute Value Pairs		that raise the need for protecting Diameter Attribute-Value Pairs
	(AVPs). Figure 1 illustrates an example Diameter topology where a		(AVPs). Figure 1 illustrates an example of Diameter based roaming
	Diameter clients want to interact with the example.com home domain.		architecture in which Diameter clients within the visited networks
	To interconnect the two visited networks a AAA interconnection		need to interact with Diameter servers in the home domain. AAA
	provider, labeled as AAA Broker, is used.		domains are interconnected using a Diameter-based AAA interconnection
			network labeled as AAA Broker.
	+oooooooooooooooooo+ +====================+		+oooooooooooooooooo+ +====================+
	| Example.net | | |		| Example.net | | |
	| | | |		| | | |
	+--------+ +--------+ +--------+ +--------+		+--------+ +--------+ +--------+ +--------+
	|Diameter| |Diameter+--------+Diameter| |Diameter|		|Diameter| |Diameter+--------+Diameter| |Diameter|
	|Client 1+------+Proxy A1| +------+Proxy B +--------+Proxy C |----+		|Client 1+------+Proxy A1| +------+Proxy B +--------+Proxy C |----+
	+--------+ +--------+ | +--------+ +--------+ |		+--------+ +--------+ | +--------+ +--------+ |
	| | | | | |		| | | | | |
	| Visited Domain 1 | | | AAA Broker | |		| Visited Domain 1 | | | AAA Broker | |
	skipping to change at page 4, line 38 ¶		skipping to change at page 4, line 38 ¶
	| |		| |
	| Visited Domain 2 |		| Visited Domain 2 |
	+oooooooooooooooooo+		+oooooooooooooooooo+
	Figure 1: Example Diameter Deployment.		Figure 1: Example Diameter Deployment.
	Eavesdropping: Some Diameter applications carry information that is		Eavesdropping: Some Diameter applications carry information that is
	only intended for consumption by end points, either by the		only intended for consumption by end points, either by the
	Diameter client or by the Diameter server but not by		Diameter client or by the Diameter server but not by
	intermediaries. As an example, consider the Diameter EAP		intermediaries. As an example, consider the Diameter EAP
	application [4] that allows keying material for the protection of		application [4] that allows the transport of keying material
	air interface between the end device and the network access server		between the Diameter server to the Diameter client (using the EAP-
	to be carried from the Diameter server to the Diameter client		Master-Session-Key AVP) for the protection of air interface
	(using the EAP-Master-Session-Key AVP). The content of the EAP-		between the end device and the network access server. The content
	Master-Session-Key AVP would benefit from protection against		of the EAP-Master-Session-Key AVP should benefit from protection
	eavesdropping by intermediaries. Other AVPs might also carry		against eavesdropping by intermediaries. Other AVPs, for example
	sensitive personal data that, when collected by intermediaries,		those listed in Section 13.3 of [2], might also carry sensitive
	allow for traffic analysis.		personal data that, when collected by intermediaries, allow for
			traffic analysis.
	In context of the deployment shown in Figure 1 the adversary		In context of the deployment shown in Figure 1 the adversary
	could, for example, be in the AAA broker network.		could, for example, be in the AAA broker network.
	Injection and Manipulation: The Diameter base specification mandates		Injection and Manipulation: The Diameter base protocol specification
	security protection between neighboring nodes but Diameter agents		mandates security protection between neighboring nodes but
	may be compromised or misconfigured and inject/manipulate AVPs.		Diameter agents may be compromised or misconfigured and inject/
	To detect such actions additional security protection needs to be		manipulate AVPs. To detect such actions additional security
	applied at the Diameter layer.		protection needs to be applied at the Diameter layer.
	Nodes that could launch such an attack are any Diameter agents		Nodes that could launch such an attack are any Diameter agents
	along the end-to-end communication path.		along the end-to-end communication path.
	Impersonation: Imagine a case where a Diameter message from		Impersonation: Imagine a case where a Diameter message from
	Example.net contains information claiming to be from Example.org.		Example.net contains information claiming to be from Example.org.
	This would either require strict verification at the edge of the		This would either require strict verification at the edge of the
	AAA broker network or cryptographic assurance at the Diameter		AAA broker network or cryptographic assurance at the Diameter
	layer to prevent a successful impersonation attack.		layer to prevent a successful impersonation attack.
	Any Diameter realm could launch such an attack aiming for		Any Diameter realm could launch such an attack aiming for
	financial benefits or to disrupt service availability.		financial benefits or to disrupt service availability.
	4. Scenarios for Diameter AVP-Level Protection		4. Scenarios for Diameter AVP-Level Protection
	This scenario outlines a number of cases for deploying security		This scenario outlines a number of cases for deploying security
	protection of individual Diameter AVPs.		protection of individual Diameter AVPs.
	In the first scenario, shown in Figure 2, end-to-end security		In the first scenario, shown in Figure 2, end-to-end security
	protection is provided between the Diameter client and the Diameter		protection is provided between the Diameter client and the Diameter
	server. Diameter AVPs exchanged between these two Diameter nodes are		server with any number of intermediate Diameter agents. Diameter
	protected.		AVPs exchanged between these two Diameter nodes may be protected end-
			to-end (notation '{AVP}k') or unprotected (notation 'AVP').
	+--------+ +--------+		+--------+ +--------+
	|Diameter| AVP, {AVP}k |Diameter|		|Diameter| AVP, {AVP}k |Diameter|
	|Client +-----------------........... -------------------+Server |		|Client +-----------------........... -------------------+Server |
	+--------+ +--------+		+--------+ +--------+
	Figure 2: End-to-End Diameter AVP Security Protection.		Figure 2: End-to-End Diameter AVP Security Protection.
	In the second scenario, shown in Figure 3, a Diameter proxy acts on		In the second scenario, shown in Figure 3, a Diameter proxy acts on
	behalf of the Diameter client with regard to security protection. It		behalf of the Diameter client with regard to security protection. It
	applies security protection to outgoing Diameter AVPs and verifies		applies security protection to outgoing Diameter AVPs and verifies
	incoming AVPs.		incoming AVPs. Typically, the proxy enforcing the security
			protection belongs to the same domain as the Diameter client/server
			without end-to-end security features.
	+--------+ +--------+ +--------+		+--------+ +--------+ +--------+
	|Diameter| AVP |Diameter| AVP, {AVP}k |Diameter|		|Diameter| AVP |Diameter| AVP, {AVP}k |Diameter|
	|Client +-----+Proxy A +---------- .......... -----------+Server |		|Client +-----+Proxy A +---------- .......... -----------+Server |
	+--------+ +--------+ +--------+		+--------+ +--------+ +--------+
	Figure 3: Middle-to-End Diameter AVP Security Protection.		Figure 3: Middle-to-End Diameter AVP Security Protection.
	In the third scenario shown in Figure 4 a Diameter proxy acts on		In the third scenario shown in Figure 4 a Diameter proxy acts on
	behalf of the Diameter server.		behalf of the Diameter server.
	skipping to change at page 6, line 21 ¶		skipping to change at page 6, line 28 ¶
	+--------+ +--------+ +--------+		+--------+ +--------+ +--------+
	Figure 4: End-to-Middle Diameter AVP Security Protection.		Figure 4: End-to-Middle Diameter AVP Security Protection.
	The fourth and the final scenario (see Figure 5) is a combination of		The fourth and the final scenario (see Figure 5) is a combination of
	the end-to-middle and the middle-to-end scenario shown in Figure 4		the end-to-middle and the middle-to-end scenario shown in Figure 4
	and in Figure 3. From a deployment point of view this scenario is		and in Figure 3. From a deployment point of view this scenario is
	easier to accomplish for two reasons: First, Diameter clients and		easier to accomplish for two reasons: First, Diameter clients and
	Diameter servers remain unmodified. This ensures that no		Diameter servers remain unmodified. This ensures that no
	modifications are needed to the installed Diameter infrastructure.		modifications are needed to the installed Diameter infrastructure.
	Second, key management is also simplified since fewer number of key		Second, key management is also simplified since fewer number of keys
	pairs need to be negotiated and provisioned.		need to be negotiated and provisioned.
	+--------+ +--------+ +--------+ +--------+		+--------+ +--------+ +--------+ +--------+
	|Diameter| AVP |Diameter| AVP, {AVP}k |Diameter| AVP |Diameter|		|Diameter| AVP |Diameter| AVP, {AVP}k |Diameter| AVP |Diameter|
	|Client +-----+Proxy A +-- .......... ----+Proxy D +-----+Server |		|Client +-----+Proxy A +-- .......... ----+Proxy D +-----+Server |
	+--------+ +--------+ +--------+ +--------+		+--------+ +--------+ +--------+ +--------+
	Figure 5: Middle-to-Middle Diameter AVP Security Protection.		Figure 5: Middle-to-Middle Diameter AVP Security Protection.
	Various security threats are mitigated by selectively applying		Various security threats are mitigated by selectively applying
	security protection for individual Diameter AVPs. Without protection		security protection for individual Diameter AVPs. Without protection
	skipping to change at page 7, line 7 ¶		skipping to change at page 7, line 10 ¶
	Modification of certain Diameter AVPs may not necessarily be the act		Modification of certain Diameter AVPs may not necessarily be the act
	of malicious behavior but could also be the result of		of malicious behavior but could also be the result of
	misconfiguration. An over-aggressively configured firewalling		misconfiguration. An over-aggressively configured firewalling
	Diameter proxy may also remove certain AVPs. In most cases data		Diameter proxy may also remove certain AVPs. In most cases data
	origin authentication and integrity protection of AVPs will provide		origin authentication and integrity protection of AVPs will provide
	the most benefits for existing deployments with minimal overhead and		the most benefits for existing deployments with minimal overhead and
	(potentially) operating in a full-backwards compatible manner.		(potentially) operating in a full-backwards compatible manner.
	5. Requirements		5. Requirements
	Requirement #1: Solutions MUST support an extensible set of		Requirement #1: The solution MUST support an extensible set of
	cryptographic algorithms.		cryptographic algorithms.
	Motivation: Solutions MUST be able to evolve to adapt to		Motivation: Solutions MUST be able to evolve to adapt to
	evolving cryptographic algorithms and security requirements.		evolving cryptographic algorithms and security requirements.
	This may include the provision of a modular mechanism to allow		This may include the provision of a modular mechanism to allow
	cryptographic algorithms to be updated without substantial		cryptographic algorithms to be updated without substantial
	disruption to deployed implementations.		disruption to deployed implementations.
	Requirement #2: Solutions MUST support confidentiality, integrity,		Requirement #2: The solution MUST support confidentiality,
	and data-origin authentication. Solutions for integrity		integrity, and data-origin authentication. Solutions for
	protection MUST work in a backwards-compatible way with existing		integrity protection MUST work in a backwards-compatible way with
	Diameter applications.		existing Diameter applications.
	Requirement #3: Solutions MUST support replay protection. All		Requirement #3: The solution MUST support replay protection. All
	Diameter nodes have access to network time and thus can		Diameter nodes have access to network time and thus can
	synchronize their clocks.		synchronize their clocks.
	Requirement #4: Solutions MUST support the ability to delegate		Requirement #4: The solution MUST support the ability to delegate
	security functionality to another entity		security functionality to another entity
	Motivation: As described in Section 4 the ability to let a		Motivation: As described in Section 4 the ability to let a
	Diameter proxy to perform security services on behalf of all		Diameter proxy to perform security services on behalf of all
	clients within the same administrative domain is important for		clients within the same administrative domain is important for
	incremental deployability. The same applies to the other		incremental deployability. The same applies to the other
	communication side where a load balancer terminates security		communication side where a load balancer terminates security
	services for the servers it interfaces.		services for the servers it interfaces.
	Requirement #5: Solutions MUST be able to selectively apply their		Requirement #5: The solution MUST be able to selectively apply their
	cryptographic protection to certain Diameter AVPs.		cryptographic protection to certain Diameter AVPs.
	Motivation: Some Diameter applications assume that certain AVPs		Motivation: Some Diameter applications assume that certain AVPs
	are added, removed, or modified by intermediaries. As such, it		are added, removed, or modified by intermediaries. As such, it
	MUST be possible to apply security protection selectively.		MUST be possible to apply security protection selectively.
	Furthermore, there are AVPs that MUST NOT be confidentiality		Furthermore, there are AVPs that MUST NOT be confidentiality
	protected but MAY still be integrity protected such as those		protected but MAY still be integrity protected such as those
	required for Diameter message routing.		required for Diameter message routing.
	Requirement #6: Solutions MUST recommend a mandatory-to-implement		Requirement #6: The solution MUST define a mandatory-to-implement
	cryptographic algorithm.		cryptographic algorithm.
	Motivation: For interoperability purposes it is beneficial to		Motivation: For interoperability purposes it is beneficial to
	have a mandatory-to-implement cryptographic algorithm specified		have a mandatory-to-implement cryptographic algorithm specified
	(unless profiles for specific usage environments specify		(unless profiles for specific usage environments specify
	otherwise).		otherwise).
	Requirement #7: Solutions MUST support symmetric keys and asymmetric		Requirement #7: The solution MUST support symmetric keys and
	keys.		asymmetric keys.
	Motivation: Symmetric and asymmetric cryptographic algorithms		Motivation: Symmetric and asymmetric cryptographic algorithms
	provide different security services. Asymmetric algorithms,		provide different security services. Asymmetric algorithms,
	for example, allow non-repudiation services to be offered.		for example, allow non-repudiation services to be offered.
	Requirement #8: A solution for dynamic key management MUST be		Requirement #8: A solution for dynamic key management MUST be
	included in the overall solution framework. However, it is		included in the overall solution framework.
	assumed that no "new" key management protocol needs to be
	developed; instead existing ones are re-used, if at all possible.		However, it is assumed that no "new" key management protocol
	Rekeying could be triggered by (a) management actions and (b)		needs to be developed; instead existing ones are re-used, if at
	expiring keying material.		all possible. Rekeying could be triggered by (a) management
			actions and (b) expiring keying material.
	6. Security Considerations		6. Security Considerations
	This entire document focused on the discussion of new functionality		This entire document focused on the discussion of new functionality
	for securing Diameter AVPs selectively between non-neighboring nodes.		for securing Diameter AVPs selectively between non-neighboring nodes.
	7. IANA Considerations		7. IANA Considerations
	This document does not require actions by IANA.		This document does not require actions by IANA.
	8. Acknowledgments		8. Acknowledgments
	We would like to thank Guenther Horn, Martin Dolly, Steve Donovan and		We would like to thank Guenther Horn, Martin Dolly, Steve Donovan,
	Tom Taylor for their review comments.		Lionel Morand and Tom Taylor (rest in peace Tom) for their review
			comments.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[1] Bradner, S., "Key words for use in RFCs to Indicate		[1] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119,
			DOI 10.17487/RFC2119, March 1997,
			<http://www.rfc-editor.org/info/rfc2119>.
	[2] Fajardo, V., Arkko, J., Loughney, J., and G. Zorn,		[2] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
	"Diameter Base Protocol", RFC 6733, October 2012.		Ed., "Diameter Base Protocol", RFC 6733,
			DOI 10.17487/RFC6733, October 2012,
			<http://www.rfc-editor.org/info/rfc6733>.
	9.2. Informative References		9.2. Informative References
	[3] Calhoun, P., Farrell, S., and W. Bulley, "Diameter CMS		[3] Calhoun, P., Farrell, S., and W. Bulley, "Diameter CMS
	Security Application", draft-ietf-aaa-diameter-cms-sec-04		Security Application", draft-ietf-aaa-diameter-cms-sec-04
	(work in progress), March 2002.		(work in progress), March 2002.
	[4] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible		[4] Eronen, P., Ed., Hiller, T., and G. Zorn, "Diameter
	Authentication Protocol (EAP) Application", RFC 4072,		Extensible Authentication Protocol (EAP) Application",
	August 2005.		RFC 4072, DOI 10.17487/RFC4072, August 2005,
			<http://www.rfc-editor.org/info/rfc4072>.
	Authors' Addresses		Authors' Addresses
	Hannes Tschofenig		Hannes Tschofenig
	ARM Limited		ARM Limited
	Austria		Austria
	Email: Hannes.tschofenig@gmx.net		Email: Hannes.tschofenig@gmx.net
	URI: http://www.tschofenig.priv.at		URI: http://www.tschofenig.priv.at
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