CN1698308B - Method and apparatus enabling reauthentication in a cellular communication system - Google Patents

Abstract

A method (and corresponding equipment) for us in reauthentication--after a first, full authentication by a first authentication server (23a)--of a communication session involving the exchange of information between a terminal (21) and a server (24), the method including: a step (11) in which the first authentication server (23a) and other authentication servers (23b) are each assigned a respective unique realm name; and a step (13) in which during authentication between the terminal and the first authentication server (23a), the first authentication server (23a) transmits to the terminal (21) a reauthentication identity including the unique realm name assigned to the first authentication server. Then, later, during reauthentication, to make possible that the reauthentication is performed by the same authentication server (23a) as performed the full authentication--i.e. by the first authentication server (23a)--the reauthentication identity is included in a request for reauthentication.

Description

Method and apparatus allowing re-authentication in a cellular communication system

Cross References to Related Applications

This application claims priority to US Provisional Application Serial No. 60/416,481, filed October 3, 2002, entitled "EAPAKA and SIM Authentication." the

technical field

The present invention relates to Extensible Authentication Protocol (EAP) mechanisms for authentication and session key distribution in communication systems such as Authentication and (Session) Key (Distribution) Protocol (AKA) for Universal Mobile Telecommunications System (UMTS) The EAP mechanism is another example of the EAP mechanism for AKA implemented in the Subscriber Identity Module (SIM) used in the Global System for Mobile Communications (GSM). More specifically, the present invention relates to the use of EAP mechanisms for re-authentication in GSMSIM or UMTSAKA authenticated communication systems.

Background technique

AKA is based on query-response mechanism and symmetric cryptography. In UMTS, it can refer to 3GPPTS (Technical Specification) 33.102 V3.6.0 issued by 3GPP (Third Generation Partnership Project) in November 2000: "Technical Specification Group Service and system aspects; 3G security; security architecture (1999 edition)". AKA typically runs in a UMTS Subscriber Identity Module (USIM), a smart card-like device. However, the application of AKA is not limited to client devices containing smart cards; for example, AKA can also be implemented with host software. AKA also provides backward compatibility with the GSM authentication mechanism, which was published by the European Telecommunications Standards Institute in August 1997 in GSM03.20 (ETS 300 534): "Digital Cellular Telecommunications Systems (Phase 2); Security Related Network Capabilities". Compared to the GSM mechanism, AKA provides a much longer key length and provides authentication of the server side (as well as the client side).

In order for a client device such as a wireless terminal (more specifically, a mobile station) to use services provided by a server (such as a server in a communication system provided and managed by an operator) (or services including a server of any type of network such as the Internet), the user A terminal must under certain circumstances (for certain networks and certain services of those networks) authenticate itself to a server and vice versa. (At least in some networks, notably UMTS, the server must authenticate itself to the client), ie each party must prove to the other party who it claims to be. On dial-up networks, wireless LANs, wired LAN networks and various Digital Subscriber Line (xDSL) networks, the operator of the network usually employs a so-called AAA (Authentication, Authorization and Accounting) server to authenticate the client and to authenticate the client's service The server of the carrier's network (or authenticating carrier's network regardless of any particular server) the request is sent to. The AAA server may be responsible for storing shared secrets and other secrets needed to authenticate users (terminals with components specific to a particular user and thus identifying the user), or the AAA server may use a separate user database server for storing these secrets information. Extensible Authentication Protocol (EAP) is generally used on a network employing an AAA server to perform authentication between the AAA server and a terminal. If the operator of the network is a cellular operator of a UMTS or GSM network, the EAP method may encapsulate enhanced GSM authentication and key agreement as in EAP SIM, or enhanced UMTS authentication and key agreement as in EAP AKA. The terminal exchanges authentication packets with the watch device on the local network. The on-duty device varies with the type of network, but it can be, for example, a wireless LAN access point, an Ethernet switch, and a dial-up network access server (NAS). The watch device usually operates as a so-called AAA client, and the AAA client and the AAA server perform authentication using the so-called AAA protocol.

At the beginning of a communication session established with EAP SIM or EAP AKA, the terminal and the AAA server perform so-called full authentication in this paper, that is, the authentication starts from a state where neither the terminal nor the AAA server serves as any basis for authenticating the other party.

After full authentication has been established, possibly at a predetermined time or some other condition is met, re-authentication is required to reduce the likelihood that a "bad guy" will use some other device (either a server device or a client device) to start impersonating the originally authenticated The authenticated entity, or even somehow gains physical control of the initially authenticated device (e.g. the user forgets to close the authenticated terminal and walks away) and starts sending requests. In order to confirm that the terminal is still using network resources, it may also need to re-authenticate as required by accounting messages sent by the local network. Likewise, re-authentication may also be used to negotiate new secure keys for security reasons where the keys have a limited lifetime. Reauthentication is exactly the same in EAP SIM (corresponding to GSM) and EAP AKA (corresponding to UMTS).

The prior art EAP SIM and EAP AKA protocols provide re-authentication using the re-authentication user identity respectively passed from the AAA server to the terminal being re-authenticated. Reauthentication is based on the session key and other contextual information established during the full authentication process.

Operators may deploy multiple AAA servers in the network for load balancing and other reasons. Since an AAA server may be selected randomly or through some predetermined mechanism such as a polling mechanism to authenticate the terminal, the terminal (user) may not always authenticate to the same AAA server. In such networks, reauthentication becomes problematic if the context information is only stored in AAA servers that have performed full authentication. Because reauthentication assumes the validity of some information provided during the full authentication process, if the terminal's reauthentication AAA request is forwarded to another AAA server than the one that performed the full authentication, reauthentication cannot be performed (i.e., cannot implement).

Therefore, there is a need for a method by which reauthentication can be performed in networks where reauthentication requests may be forwarded to another AAA server than the one that performed full authentication.

disclosure of invention

Accordingly, in a first aspect of the invention there is provided a method for re-authenticating a communication session involving the exchange of information between a terminal and a server over an authentication network, said communication session having been authenticated by the terminal and the authentication network has been authenticated by the first authentication server, the method is characterized in that: the step of assigning corresponding unique domain names to the first authentication server and other authentication servers; and during the authentication between the terminal and the first authentication server, the first The authentication server sends a re-authentication identity to the terminal, the re-authentication identity contains the unique domain name assigned to the first authentication server.

According to the first aspect of the present invention, the method is further characterized by: in order to perform re-authentication, the terminal sends a re-authentication request using a re-authentication identity with a unique domain name; and the authentication network element receiving the re-authentication request according to The re-authentication identity determination included in the request indicates the steps to perform the unique domain name of the fully authenticated authentication server. The method is further characterized by the step of the authentication network element forwarding the request to the authentication server indicated by the unique domain name included as part of the re-authentication identity; and the step of the terminal and the first authentication server performing the re-authentication.

In a second aspect of the present invention there is provided an authentication server in a cellular communication system comprising means for re-authenticating a communication session between a terminal and a content server, said authentication server being characterized in that it receives means for assigning a unique domain name; and means for sending a re-authentication identity including the unique domain name to the terminal.

According to the first aspect of the present invention, the authentication server is further characterized by means for receiving a re-authentication request using a re-authentication identity, and determining a unique domain name based on the re-authentication identity. The authentication server is further characterized by means for forwarding the request to the authentication server indicated by the unique domain name included as part of the re-authentication identity.

In a third aspect of the present invention there is provided a computer program product comprising: a computer readable storage structure having computer program code embodied thereon for execution by a computer processor in an authentication server, wherein the computer program code's It is characterized in that it comprises instructions for enabling means for the apparatus according to the second aspect of the invention.

In a fourth aspect of the present invention there is provided a system comprising: a plurality of terminals, a plurality of authentication servers and at least one content server; said terminal being operable to be authenticated by one or another of said authentication servers and requesting content from the content server after occasional re-authentication, the system is characterized in that at least two of the authentication servers are devices according to the second aspect of the present invention.

Brief introduction to the drawings

The above and other objects, features and advantages of the present invention can be made clear with reference to the following detailed description in conjunction with the accompanying drawings, in which:

Figure 1 is a flowchart of a method for re-authentication (to an authentication server acting as an authentication proxy) of a terminal according to the present invention;

Figure 2 is a block diagram/flow diagram of terminal authentication and subsequent re-authentication to an authentication server according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention provides a solution to the problem of how to ensure efficient re-authentication in a network where re-authentication requests may be forwarded to another AAA server than the one that performed full authentication. To solve this problem, the present invention makes it possible to select an AAA server that has performed complete authentication as the AAA server for re-authentication.

The present invention is described below in conjunction with the Extensible Authentication Protocol (EAP) mechanism for authentication and session key distribution in the Universal Mobile Telecommunications System (UMTS) Authentication and Key Agreement (AKA), which can be found in 2000 by the 3GPP organization 3GPPTS33.102 V3.6.0 published in November: "Technical Specification Group Services and System Aspects; 3G Security; Security Architecture (Version 1999)"; and IETF submitted by J.Arkko and H.Haverinen in June 2002 (Internet Engineering Task Force) draft document: "EAPAKA Authentication" (draft-arkko-pppext-eap-aka-04.txt). UMTS is the third generation mobile network standard worldwide. Obviously, the present invention can also be used in combination with the EAP mechanism for authentication and session key distribution using the Global System for Mobile Communications (GSM) Subscriber Identity Module (SIM). Specification GSM03.20 (ETS 300 534): "Digital Cellular Telecommunications System (Stage 2); Security-Related Network Functions" and IETF draft document submitted by H. Haverinen on July 2, 2002: "EAPSIM Authentication" ( draft-haverinen-ppppext-eap-sim-05.txt). Although the present invention has been described with specific reference to its use in conjunction with the Extensible Authentication Protocol and its UMTS and GSM methods, it should be understood that the present invention is not limited to use in the Extensible Authentication Protocol or cellular communication systems conforming to the UMST or GSM standards; The present invention can be used in virtually any communication system that provides authentication in a similar or comparable manner to the use of the Extensible Authentication Protocol in conjunction with the AAA protocol. In the case of the described embodiment, the invention makes use of the so-called EAP (Extensible Authentication Protocol), which can be found in RFC 2284 entitled "PPP Extensible Authentication Protocol (EAP)" published by the IETF Network Working Group. (PPP)EAP is a generic authentication protocol; it supports multiple authentication mechanisms.

Referring now to Figures 1 and 2, in order to ensure that reauthentication is always possible, the present invention proposes a method comprising a first step 11 in which a middle) to assign a unique domain name which, in the case of UMTS or GSM and IP service authentication, is the name of the type that can be used for a Network Access Identifier (NAI) (as part of the NAI, e.g. in the form user@realm, Where "realm" is a unique domain name), NAI is a (terminal) identifier used in conjunction with the AAA protocol for network access authentication. In the established EAP and AAA protocols, the authentication request contains the user's network access identifier. In case of full authentication, EAP SIM and EAP AKA specify the identity format that the terminal will use to request full authentication. Depending on the specification specified, the username part of the NAI contains the International Mobile Subscriber Identifier (IMSI) or a temporary identifier called a pseudonym in the EAP SIM and EAP AKA specifications. Domain names used in NAI are usually public identifiers attributed to operators. Several AAA servers may be employed to service requests directed to the domain name. Therefore, according to the prior art, usually the domain names in the NAI can be shared by several AAA servers. For example: a user of MyOperator may use the domain name myoperator.com, and AAA messages are routed to one of these AAA servers for myoperator.com. In EAP SIM and EAP AKA full authentication, the domain name may indicate a set of AAA servers. However, according to the present invention, each AAA server will be assigned a unique domain name, eg, serverX.myoperator.com, which is the unique domain name that will be used in the re-authentication identity. Here, the third-level name serverX makes the domain name serverX.myoperator.com the only domain name. The structured format of this domain name may allow certain AAA network elements to route all domains ending in myoperator.com to the correct next hop, regardless of the third-level name that must be added to make the domain name unique; e.g., on-duty device 21a It may not be necessary to care about the full domain name, but a simple rule: "route *.myoperator.com to MyOperator's AAA proxy" (where * is used as a wildcard, i.e., it denotes any set of characters allowed in the name).

In the next step 12, the first server 23a in the AAA servers 23a and 23b receives the (complete ) authentication request, so the on-duty equipment 21a can agree to the terminal 21 accessing the network 24 (such as the Internet). The various network elements of one or more operator networks that enable wireless communication between the terminal 21 and the AAA servers 23a and 23b (specifically the radio interface of each operator network) are not shown in FIG. 2 (for clarity). network access) and other network elements that route communications to one or the other of the AAA servers 23a and 23b.

In the next step 13, the first AAA server 23a (via the proxy server 22 and the duty device 221a) sends a re-authentication identity to the terminal 21 (for use by the terminal in a later re-authentication operation), and upon said re-authentication identity Contains the unique domain name, which also includes the username portion. The re-authentication identity is different from the IMSI-based and pseudonymous identities used for full authentication. Step 13 is performed as part of a complete authentication procedure which also includes other steps which have been omitted from Figure 1 for the sake of brevity. The username portion of the re-authentication identity is a one-time username chosen by the server. It can be a randomly chosen number or an identifier. So the re-authentication identity could be, for example:

1209834387@server15.myoperator.com.

In a next step 14, for re-authentication (usually based on some fulfilled conditions), the terminal 21 sends a re-authentication request using a re-authentication identity with a unique domain name. In general, reauthentication can be initiated in several ways. In one way, re-authentication can be initiated by the watch device 21a. In this case, on the wireless LAN (where the "re-authentication request" forwarded according to the unique domain name contains the EAP identity response packet), the duty device 21a sends an EAP identity request packet to the terminal 21, which takes the EAP identity containing the re-authentication identity Respond to respond. The packet is then forwarded to the correct AAA server via the AAA protocol. Alternatively, the terminal 21 itself can initiate re-authentication. On the wireless LAN, the terminal 21 transmits an EAPOL-Start (EAP over LAN start) packet to the duty device 21a. On receipt of EAPOL-Start, watch device 21a sends an EAP Identity Request packet to the terminal, and the re-authentication exchange then continues as described below.

In the next step 15, any AAA network element (attendment device 21a, proxy 22, and AAA servers 23a and 23b) receiving the request checks the re-authentication identity contained in the request to determine where to route the request ( According to the re-authentication identity of the first AAA server 23a indicated by the domain name). This routing is based on routing tables or other common AAA routing methods as appropriate. Typically, the proxy server 22 checks the domain name and routes the request directly to the first AAA server 23a. Therefore, sooner or later, the AAA server that has performed the full authentication (ie the first AAA server 23a) will receive the request.

In the next step 16, the first AAA server 23a responds to the re-authentication request according to the established re-authentication protocol. In the next step 17, according to the established AAA protocol, subsequent communication between the terminal 21 and the first AAA server 23a is performed between the terminal 21 and the first AAA server 23a through the duty device 21a. Subsequent communications may be routed directly between the watch device 21a and the first AAA server 23a or through intermediate AAA network elements. A formulated AAA protocol typically includes means for ensuring that the AAA server 23a performing the authentication does not change during an authentication exchange.

In some instances, terminal 21 may communicate through several different sessions simultaneously, using the full authentication procedure for each session. These sessions may be authenticated by the same AAA server or by different AAA servers, and may utilize the same or different radio technologies and the same or different applications for performing the authentication. According to the present invention, to accommodate this variability, terminal 21 maintains individual state information for each such session, and terminal 21 can then perform re-authentication for each such session separately, as described in connection with FIG. 1 . Correspondingly, each AAA server 23a and 23b for authenticating one or more simultaneous sessions maintains respective state information for each such session.

Note that while the present invention relates to wireless LAN authentication, it is relevant to xDSL, dial-up networking, Ethernet and other authentication contexts. Extensible Authentication Protocol methods for UMTS and GSM authentication will be targeted by mobile operators wishing to manage WLANs or other supplementary access networks; it is also possible that the invention will never be applied in actual UMTS or GSM networks.

It is to be understood that the above arrangement is merely illustrative of the application of the principles of the invention. Various modifications and alternative arrangements can be devised by those skilled in the art without departing from the scope of the invention, and the appended claims are intended to cover such modifications and arrangements.

Claims (7)

1. A method for re-authentication of a communication session involving an exchange of information between a terminal and a server over an authentication network, said method being implemented in a first authentication server of said authentication network, said communication session having been authenticated by The terminal has been authenticated by the first authentication server, and the method includes: Receive the terminal's complete authentication request; sending a re-authentication identity to the terminal, the re-authentication identity including a unique domain name uniquely identifying the first authentication server; and receiving a re-authentication request from the terminal from an authentication network element, wherein the re-authentication request includes the re-authentication identity including the unique domain name that uniquely identifies the first authentication server, and the re-authentication request is the The authentication network element is routed to the first authentication server according to the unique domain name included in the re-authentication request. 2. The method of claim 1, wherein the unique domain name uniquely identifying the first authentication server performing a complete authentication of the terminal is determined from the re-authentication identity contained in the re-authentication request . 3. The method of claim 2, further comprising: Re-authentication of the terminal is performed in response to the re-authentication request. 4. A device for re-authentication of a communication session involving an exchange of information between a terminal and a server over an authentication network, said device being implemented in a first authentication server of said authentication network, said communication session having been performed by The terminal has been authenticated by the first authentication server, and the device includes: means for receiving a complete authentication request from a terminal; means for sending a re-authentication identity to the terminal, the re-authentication identity including a unique domain name uniquely identifying the first authentication server; and means for receiving a re-authentication request from the terminal from an authentication network element, wherein the re-authentication request includes the re-authentication identity including the unique domain name that uniquely identifies the first authentication server, and the re-authentication The authentication request is routed by the authentication network element to the first authentication server according to the unique domain name included in the re-authentication request. 5. A system comprising: a first authentication server configured to receive a complete authentication request from a terminal and configured to send to the terminal a re-authentication identity comprising a unique domain name uniquely identifying the first authentication server; and an authentication network element configured to receive a re-authentication request from the terminal, the re-authentication request including the re-authentication identity including the unique domain name uniquely identifying the first authentication server, and configured to Routing the re-authentication request to the first authentication server based on the unique domain name identifying the first authentication server. 6. A device for re-authentication of a communication session involving an exchange of information between a terminal and a server over an authentication network, said device being implemented in said terminal, said communication session having been performed by said terminal and a first The authentication server has been authenticated, and the device includes: means for sending a complete authentication request to said first authentication server; means for receiving from said first authentication server a re-authentication identity comprising a unique domain name that uniquely identifies said first authentication server; and means for sending a re-authentication request using said re-authentication identity including said unique domain name to an authenticating network element. 7. The apparatus of claim 6, wherein the means for sending to the authenticating network element comprises means for including the re-authentication identity in an Extensible Authentication Protocol identity response.

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