ABFAB Y. Wei, Ed. Internet-Draft ZTE Corporation Intended status: Informational October 31, 2011 Expires: May 3, 2012 Federated Cross-Layer Access draft-wei-abfab-fcla-01 Abstract Network stratum and application stratum form a federation to faciliate user's access. Network operator acts as Identity Provider (IdP), and application reuses underlying network's security capabilities to simlify application's access. This document is to introduce such federated cross-layer access use case and message flows. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on May 3, 2012. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as Wei Expires May 3, 2012 [Page 1] Internet-Draft Federated Cross-Layer Access October 2011 described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Use Case . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Message Flow . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8.1. Normative References . . . . . . . . . . . . . . . . . . . 8 8.2. Informative References . . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9 Wei Expires May 3, 2012 [Page 2] Internet-Draft Federated Cross-Layer Access October 2011 1. Introduction Currently it is agreed that digital identity is a crucial element in a service enviroment. Typically telecom operators provide access customers with identity which is associated with some form of trusted element on the network (e.g. SIM/UICC). Meanwhile the identity required by Web or non-Web services for users on is usually associated with username. Ordinarly telecom operators have tens of millons of users and can provide trusted identity and higher security. However the categories of service provided by telecom operators are relatively few. On the contrary most service providers on the Internet have limited amount of users and can not assure the security of user identity, but they can provide abundant kinds of service. Furthermore, user is reluntant to register too many accounts because it is inconvenient to remember dozens of passwords . These facts creates some driving forces that telecom is interworking with Internet. The stakeholders can benifit from these combination. For telecom operators, they can provide identity service, trusted security service, mobile payment service and sharing some user profiles according user's preferences. Telecom operators is not just providing pipeine for communication, but also become a part of service value chain. For service providers, they can focus on core business and reuse capabilities provided by telecom operators without worring about sources of users. For end users, they can enjoy seamless service experiences and improve security and privacy. This document considers a use case which telecom operator acts as Identity provider (IdP) and federates with non-Web applications, e.g. Email, Messaging. This use case combines network stratum access and application stratum access, which is named as federated cross-layer access. The detailed message flows for this use case are given. 2. Related Work GSMA Association IDM project address operators' requirements for emerging mobile application (such as, Single Sign-on, mobile payments and other UICC enabled applications). Several use cases are also identified[GSMA_IDM]. Liberty Alliance Telecommunications SIG investigates digital identity grown in both telecom and Internet, develops several use cases and proposes correspoding solutions for interworking these two different domains [TelecoSiG]. GBA (Generic Bootsrapping Authentication) mechanism for boostrapping authentication and key agreement for application is denfined in [TS33.220]. The interworking between GBA and Identity Federation Wei Expires May 3, 2012 [Page 3] Internet-Draft Federated Cross-Layer Access October 2011 Framework (ID-FE) is documented in [TR33.980]. Another interworking case between GBA and OpenID is specified in [TR33.924]. Currently some use cases [I-D.ietf-abfab-usecases], architecture [I-D.lear-abfab-arch] and mechanisms are developed in IETF abfab working group. 3. Use Case Editor's Note: The section WILL be removed if this use case is adopted in [I-D.ietf-abfab-usecases]. Telecom operators have a communication network infrastructures to provider users with a wealthy of access methods. Telecom operators have a huge number of registered users, and they can provide trusted identity and higher security. Therefore they have a natural advantage to act as an Identity Provider (IdP) to serve for service providers. On the contrary most service providers on the Internet have limited amount of users and can not assure the security of user identity, but they can provide abundant kinds of service. Furthermore, user is reluctant to register too many accounts because it is inconvenient to remember dozens of passwords. Telecom network supports Web or non-Web application. In some cases user prefers to choose non-Web application, e.g. Messaging service, VoIP, EMail service, etc. Based on the result of network stratum authentication and authorization, User equipment (UE) can access applications without doing another authentication and authorization procedure. In this way, the system can implement federated cross- layer access. Firstly mutual authentication is performed between UE and Network, secondly UE accesses Application based on the result of network stratum's authentication. In this case, a federation is formed between Network and Application. For federated cross-layer access, Network can assure the Application of the authenticity of user's identity, share some of use profile with Application. These can bring some benifits to stakeholders: o For telecom operators, it becomes part of the business value chain as an Identity Provider. o For service provider, it can focus on core competitive services without worrying about the number of registered users by reusing underlying security mechanisms during network stratum access. o For end users, seamless sevice is provided, security and privacy are improved. Wei Expires May 3, 2012 [Page 4] Internet-Draft Federated Cross-Layer Access October 2011 4. Message Flow Take mobile network for example, UE has pre-shared key (PSK) with HSS. UE is mutully authenticated with network during attach procedure. After authentication, a master session key (MSK) is created on both UE and AAA. EAP [RFC3748] can enable the above procedure. +-------------+ + Application | / +------+------+ / | / | / | / | / +-----+----+ +---+--+ | | | UE +----------+ Network | +------+ | | +----------+ Figure 1: Federated Cross-Layer Access Figure 1 shows the relation among UE, network and application. Firstly mutual authentication is performed between UE and Network, secondly UE accesses Application using Single Sign-ON (SSO) based on network stratum's authentication. In this case, a federation is formed between Network and Application. The brief steps are as follows: 1. When UE attach the Network, mutual authentication is performed master session key is created between them. 2. UE visits non-Web Application, e.g Messageing service, VoIP service, or Email service. 3. Application has no information about the UE. The Application contacts Network to validate the authentication result in the network stratum. Application can find Network according the configuration or dynamical discovery protocol. 4. Network responds to Application with authentication result. 5. UE is authorized to access the Application. The message flows below make use of the security capabilities provided by network and some building blocks, such as GSS-API, AAA- SML etc. Editor's Note: The usage of GSS-EAP [I-D.ietf-abfab-gss-eap] in this case will be considered next time. Wei Expires May 3, 2012 [Page 5] Internet-Draft Federated Cross-Layer Access October 2011 +------+ +--------+ +------+ +------+ | UE | | NAS | | IdP | | RP | +---+--+ +----+---+ +---+--+ +---+--+ | | | | +-+-----------------+----------------+-+ | | 1. Network Access Authentication | | +-+-----------------+----------------+-+ | | 2. Access Application | | +-------------------------------------------------->| | | | 3. AAA Request | | | |<---------------+ | | | 4. AAA Response| | | +--------------->| | | | +-------+-------+ | | | |5. Validate the| | | | | Signature | | | | +-------+-------+ | 6. Establish Secure Channel | | |<--------------------------------------------------+ | | | | Figure 2: Message Flow - 1 1. When UE access network, UE is performed mutual authentication with network. EAP can be utilized to faciliate the authentication procedure. EAP-Identity and EAP-Method will be exchanged between UE and network element. After sucessful authentication, an shared MSK is generated and stored in UE and IdP respectively, which can be used to authenticate other applications and then establish secure channels. 2. UE accesses Relying Party (RP). UE is identified by NAI [RFC4282]. GSS-API [RFC4121] is acted as underlying transport mechanisms. The required credential is derived from step 1. 3. When RP receieves the request from UE, it checkes whether the credential is avialable. If not, RP initiates AAA request to retrieve credential from IdP [I-D.ietf-abfab-aaa-saml] [I-D.jones-diameter-abfab]. 4. IdP constructs the SAML artefact by means of NAI and MSK generated in step 1. AAA response with SAML message sends to RP. 5. RP validates the signature in the SAML message. 6. RP establishes secure channel with UE by means of GSS-API. Wei Expires May 3, 2012 [Page 6] Internet-Draft Federated Cross-Layer Access October 2011 +------+ +--------+ +------+ +------+ | UE | | BSF | | IdP | | RP | +---+--+ +----+---+ +---+--+ +---+--+ | | | | +-+-----------------+----------------+-+ | | 1. Boostrapping Procedure | | +-+-----------------+----------------+-+ | | 2. Access Application | | +-------------------------------------------------->| | | | 3. AAA Request | | | |<---------------+ | | | 4. AAA Response| | | +--------------->| | | | +-------+-------+ | | | |5. Validate the| | | | | Signature | | | | +-------+-------+ | 6. Establish Secure Channel | | |<--------------------------------------------------+ | | | | Figure 3: Message Flow - 2 This case makes use of BSF (Boostrapping Server Function) defined in [TS33.220]. In Step 1, after the boostrapping procedure, a shared session key is generated between UE and IdP, which is used to authenticate UE by RP and establish secure channel between UE and RP. Step 2~6 is similar to procedures in Figure 2. 5. Acknowledgements The author would like to thank Klaas Wierenga, Hannes Tschofenig, Sam Hartman, Rhys Smith, Tao Fu, Zhengxue Xia for their valuable comments. 6. IANA Considerations TODO 7. Security Considerations TODO Wei Expires May 3, 2012 [Page 7] Internet-Draft Federated Cross-Layer Access October 2011 8. References 8.1. Normative References [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, "Extensible Authentication Protocol (EAP)", RFC 3748, June 2004. [RFC4121] Zhu, L., Jaganathan, K., and S. Hartman, "The Kerberos Version 5 Generic Security Service Application Program Interface (GSS-API) Mechanism: Version 2", RFC 4121, July 2005. [RFC4282] Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The Network Access Identifier", RFC 4282, December 2005. 8.2. Informative References [I-D.lear-abfab-arch] Howlett, J., Hartman, S., Tschofenig, H., and E. Lear, "Application Bridging for Federated Access Beyond Web (ABFAB) Architecture", draft-lear-abfab-arch-02 (work in progress), March 2011. [I-D.ietf-abfab-usecases] Smith, R., Tysom, M., and S. Cooper, "Application Bridging for Federated Access Beyond web (ABFAB) Use Cases", draft-ietf-abfab-usecases-00 (work in progress), March 2011. [I-D.ietf-abfab-aaa-saml] Howlett, J. and S. Hartman, "A RADIUS Attribute for SAML Messages", draft-ietf-abfab-aaa-saml-01 (work in progress), March 2011. [I-D.jones-diameter-abfab] Jones, M. and H. Tschofenig, "The Diameter 'Application Bridging for Federated Access Beyond Web (ABFAB)' Application", draft-jones-diameter-abfab-00 (work in progress), March 2011. [I-D.ietf-abfab-gss-eap] Hartman, S. and J. Howlett, "A GSS-API Mechanism for the Extensible Authentication Protocol", draft-ietf-abfab-gss-eap-04 (work in progress), October 2011. [GSMA_IDM] Wei Expires May 3, 2012 [Page 8] Internet-Draft Federated Cross-Layer Access October 2011 GSM Association, "White paper on Identity Management Requirements, Issues, and Directions for Mobile Industry", August 2007, . [TelecoSiG] Liberty Alliance Project, "Bridging IMS and Internet Identity", December 2009, . [TS33.220] 3GPP, "Generic Authentication Architecture (GAA); Generic Bootstrapping Architecture (GBA)", 3GPP TS 33.220 10.0.0, October 2010. [TR33.980] 3GPP, "Liberty Alliance and 3GPP security interworking; Interworking of Liberty Alliance Identity Federation Framework (ID-FF), Identity Web Services Framework (ID- WSF) and Generic Authentication Architecture (GAA)", 3GPP TR 33.980 10.0.0, April 2011. [TR33.924] 3GPP, "Identity management and 3GPP security interworking; Identity management and Generic Authentication Architecture (GAA) interworking", 3GPP TR 33.924 10.1.0, June 2011. Author's Address Yinxing Wei (editor) ZTE Corporation No 68, Zijinghua Road Nanjing, Jiangsu 210012 China Phone: +86 25 52872328 Email: wei.yinxing@zte.com.cn Wei Expires May 3, 2012 [Page 9]