KR20050116821A - Wlan session management techniques with secure rekeying and logoff - Google Patents

Abstract

The invention provides a method for improving the security of a mobile terminal in a WLAN environment by installing two shared secrets instead of one shared secret, the initial session key, on both the wireless user machine and the WLAN access point during the user authentication phase. One of the shared secrets is used as the initial session key and the other is used as a secure seed. Since the initial authentication is secure, these two keys are not known to a would be hacker. Although the initial session key may eventually be cracked by the would be hacker, the secure seed remains secure as it is not used in any insecure communication.

Description

LAN SESSION MANAGEMENT TECHNIQUES WITH SECURE REKEYING AND LOGOFF}

Related Applications

This application claims the priority of US Provisional Patent Application No. 60 / 454,542, filed March 14, 2003, the contents of which are incorporated herein by reference.

The present invention relates to an apparatus and method for providing a secure communication session in a local area network, and more particularly to providing a secure communication session to a mobile terminal in a WLAN using periodic key updates and secure logoff. An apparatus and method are provided.

Background of the invention is the field of wireless local area networks or WLANs employing an IEEE 802.1x architecture with access points (APs), which access for mobile devices and hard wired local areas such as the Internet. And access to other networks, such as global networks. Due to advances in WLAN technology, rest areas, cafes, libraries, and similar public facilities (“hot spots”) become publicly accessible wireless communications. Currently, public WLANs provide mobile communication device users with access to private data networks, such as common intranets, or public data networks, such as the Internet, peer-to-peer communications, and live wireless VT broadcasts. Due to the relatively low cost of implementing and operating a public WLAN as well as the high bandwidth available (typically above 10 Mb / s), the public WLAN is an ideal access mechanism, which allows any mobile wireless communications device user to You can exchange packets with the entity. However, as described below, such open deployment may compromise security in the absence of suitable means for identification and authentication.

If a user wants to access a service within a public WLAN coverage area, the WLAN allows network access after authenticating and authorizing user access. After authentication, the public WLAN opens a secure data channel to the mobile communication device to protect the privacy of data traveling between the WLAN and the device. Currently, many WLAN equipment manufacturers employ the IEEE 802.1x protocol for deployed equipment. Therefore, a strong authentication mechanism for WLANs uses this standard. Unfortunately, the IEEE 802.1x protocol is designed to use private LAN access as the usage model for that protocol. Therefore, the IEEE 802.1x protocol does not provide features that improve security in public WLAN environments.

In a web browser-based authentication method, a mobile terminal communicates with an authentication server using a web browser that operates using the Hyper Text Transfer Protocol Secured Sockets (HTTPS) protocol, and any user in the path between the mobile terminal and the authentication server. Ensure that confidential user information cannot be infringed or stolen. However, the only information that the authentication server relates to the mobile terminal is its IP address.

If the user is authenticated by the WLAN, the user and the WLAN establish and share a secure session key. All subsequent communications are encrypted using this session key. In order to prevent security attacks, for example attacks that seek security holes in the IEEE 802.11 WEP encryption protocol, and to ensure strong security, the session key needs to be updated periodically. Indeed, if the initial session key is used as a Wired Equivalent Privacy (WEP) key, after a certain number of communication exchanges using the WEP key between the wireless user and the WLAN access point, the hacker may crack that key. . In IEEE 802.1x, the protocol used for secure access control in a WLAN where the session key is updated depends on the authentication server. In essence, every time the key is updated, the user needs to be authorized through an authentication step similar to initial authentication. This procedure may be inefficient and impossible in some applications. WLAN technology may benefit from how future key updates no longer require participation of the authentication server once the user is authenticated and the session key is established.

In addition, applications that process management information, particularly logoff requests, typically require security from hacking. However, in IEEE 802.1x, such information is transmitted in an unencrypted state, so that the mobile terminal is easily left to an attack that allows the hacker to log off an authenticated user even if the hacker does not have a session key. As such, WLAN technology may benefit from the methods provided for encryption key update or logoff requests that are further encrypted using the session key.

<Overview of invention>

A method for providing a secure communication session between a mobile terminal and a communication network preferably uses a session key to encrypt communication between the terminal and the communication network, wherein the session key is stored at the terminal and an access point of the communication network. It may be derived from a set of keys that includes a security key. Security keys can also be used to provide a secure logoff mechanism.

The present invention, during the user authentication phase, secures a mobile terminal in a WLAN environment by installing two shared keys on both the wireless user machine and the WLAN AP, instead of installing one shared secret, which is considered as the initial session key. It provides a way to improve gender. One of the shared keys is used as the initial session key and the other is used as the security seed. Since the initial authenticated communication is secure, it is almost impossible for a hacker to crack this type of protection once the two security keys are established. And although the initial session key might someday be cracked by hackers, the security seed is always kept secure because it is not used for any insecure communication.

Embodiments of the present invention include a process during which a new key is generated and exchanged between a WLAN access point and a mobile terminal. Instead of using this new key directly, the access point and mobile terminal use this new key with the security seed to generate a new session key. For example, a new session key may be generated by associating a new key with a security seed and then computing a hash function in one direction, such as a Message Digest 5 (MD5) hash algorithm, to generate a fixed string. Because hackers can't have a secure seed, even if they can crack an old session key, they won't get a new one.

Embodiments of the present invention also include a process during which a mobile terminal maintains a secure state that prevents hackers from logging off an authenticated mobile terminal. The IEEE 802.1x based scheme does not provide secure logoff because the logoff request is performed in an unencrypted frame. However, in the embodiment of the present invention, the mobile terminal transmits an encrypted logoff request performed by the secure seed. So even if the hacker cracks the session key, the logged off of the authenticated user is not possible because the security seed appears in the log off request and is no longer valid (new security seed every time the user logs in) Need to be negotiated), so even if the old security seed is cracked by a hacker, there is no harm.

Embodiments of the invention also include a method for providing a secure communication session between a mobile terminal and a wireless local access network (WLAN), the method comprising: generating first and second security keys, secure communication Using the method to transmit the first and second security keys to the mobile terminal, the first and second security keys stored in the mobile terminal for use during the secure communication session, using a current session key Encrypting and transmitting data to the mobile terminal, and receiving and decrypting data received from the mobile terminal using the current session key, wherein the first session key is initially used as the current session key; And periodically generating a subsequent session key using the second security key, and a current session during subsequent communication between the WLAN and the mobile terminal. As a step of using said next session key.

The invention also includes an apparatus for providing a secure communication session between a mobile terminal and a WLAN, the apparatus comprising: means for generating a first and a second security key and the first and second devices in the mobile terminal; Means for transmitting the security key. The mobile terminal stores the first and second security keys for subsequently decrypting the received data. In a WLAN, the means for encrypting and transmitting data to the mobile terminal uses the current session key. In the WLAN, the means for periodically generating a subsequent session key uses the second security key and uses the subsequent session key as the current session key during communication between the WLAN and the mobile terminal.

The invention is best understood from the following detailed description, which is described with reference to the accompanying drawings. Not all of the various features of the drawings are shown. In contrast, various features may be arbitrarily expanded or reduced for clarity. Included in the drawings are as follows.

1 is a block diagram of a communication system for implementing a method of the present principles for authenticating a mobile wireless communication device.

2 is a flow chart of a method for establishing two security keys in accordance with the present invention.

3 is a flowchart of a method of establishing a security logoff procedure in accordance with the present invention.

4 is a block diagram of an apparatus for practicing the present invention.

In the drawings to be discussed, circuits and associated blocks and arrows represent the functionality of the process according to the invention, which may be implemented as electrical circuits and associated wiring or data buses for transmitting electrical signals. Alternatively, one or more related arrows may represent communication (eg, data flow) between software routines, particularly when the method or apparatus of the present invention is implemented as a digital process.

According to FIG. 1, one or more mobile terminals, represented by 140 _{1 through} 140 _n , may include one or more virtual operators, such as an access point 130 _n , a local computer 120 associated with a firewall 122, and an authentication server 150 _n . (operator) 150 _1-n to communicate. Communications from terminals 140 _1-n access the security database or other sources using the Internet 110 and related communication paths 152,154, which typically require high security from unauthorized entities such as hackers. Need to do.

As shown in FIG. 1, the IEEE 802.1x architecture includes several components and services that interact to provide transparent station mobility to higher layers of the network stack. An IEEE 802.1x network defines stations such as access points 130 _1-n and mobile terminals 140 _1-n as components that communicate with the wireless medium 124 and include the functionality of the IEEE 802.1x protocol, The component is a medium access control (MAC) 138 _1-n , a corresponding physical layer (PHY) (not shown), and a connection 127 to the wireless medium. Typically, IEEE 802.1x functionality is implemented in the hardware and software of a wireless modem or network access or interface card. The present invention proposes a method for implementing the identification means in a communication stream, thereby providing an access point compatible with the IEEE 802.1x WLAN MAC layer for downlink traffic (i.e. from an authentication server to a mobile terminal such as a laptop). 130 _1-n may participate in authentication of one or more wireless mobile devices 140 _1-n , local or back end server 120, and authentication server 150.

According to the present principles, by authenticating communication streams in accordance with the IEEE 802.1x protocol as well as the mobile terminal itself, access 160 makes each mobile terminal 140 _1-n securely accessible to WLAN 115. The manner in which access 160 enables such secure access can be best understood with reference to FIGS. 1 and 2.

Under the mobile wireless communication device, that the mobile terminal (140 _n), a public WLAN (115), the sequence of interactions that take place in time between the local web server 120 and authentication server 150, the IEEE 802.1x protocol environment As illustrated, the access point 130 _n of FIG. 1 maintains a control port and an uncontrolled port through which the access point exchanges information with the mobile terminals 140 _1-n . Access point control port is held by the (130 _n), the access point to a non-function of a passage (entryway) for authentication information, such as data traffic passing through the (130 _n), which access points, the local server 120 This is because the mobile station moves between the mobile station and the mobile terminal 140 _1-n . Typically, the access point 130 _1-n maintains each control port closed in accordance with the IEEE 802.1x protocol until authentication of the appropriate mobile terminal 140 _1-n is delivered. The access point 130 _1-n keeps each uncontrolled port open at all times, causing the mobile terminal 140 _1-n to exchange authentication data with the authentication server 150.

More specifically with reference to FIG. 2, the method according to the invention for improving the security of the mobile terminal 140 _n in a WLAN environment, during the user authentication phase, is performed by the mobile terminal 140 _n and the WLAN access point. (130 _n ) Install both shared secrets instead of one shared secret. One of the shared secrets is used as the initial session key and the other is used as the security seed. Since the initial authentication is secure, these two keys are unknown to the hacker. The keys may be generated and distributed to mobile terminals and WLAN access points using known methods, such as an authentication server for generating and distributing such keys. The initial session key may someday be cracked by hackers, but the security seed remains secure because it is not used for any insecure communication. In particular, the method according to the present invention processes the web request from the mobile terminal 140 _n via the access point 130 _n to embed the session ID 215.

Referring to FIG. 2, the method according to the present invention includes installing at least two shared secrets in both the mobile terminal 140 _n and the WLAN access point 130 _n during the user authentication step, thereby providing a WLAN environment. In order to improve the security of the mobile terminal 140 _{n at} , the first secret is the initial session key and the subsequent key is used as the security seed.

In accordance with the principles of the present invention, each of the mobile communication device to, technologies that not only the device itself, can secure access to the WLAN (115) to authenticate the traffic coming from the device such as the devices (140 ₁ -140 _n) to provide. The authentication technique used in FIG. 2 illustrates a sequence of communications that occur over time between the mobile terminal 140 _n , the access point 130 _n , and the authentication server 150. To initiate secure access, the mobile terminal 140 _n sends a request for access to the access point 130 _n at step 200 of FIG. 2. In practice, mobile terminal 140 _n initiates an access request by an HTTPS access request initiated by a browser software program (not shown) executed by mobile terminal 140 _n . In response to the access request, the access point 130 _n redirects the browser software at the mobile terminal 140 _n to the local welcome page on the access point 130 _n at step 202.

Subsequent to step 202, the mobile terminal 140 _n initiates an authentication sequence by querying the access point 130 _n for the identity of the appropriate authentication server, in step 204. In response, the access point 130 _n determines, in step 206, the identity of a suitable authentication server (eg, server 150), and then, in step 208, the browser software in the mobile terminal 140 _n via an HTTP command. Send to that server. In step 208, the identity of the authentication server 150 is newly received, and in step 210 of FIG. 2, the mobile terminal 140 _n transmits its user credentials to the server.

Upon receiving the user credentials from the mobile terminal 140 _n , the authentication server 150 determines whether the mobile terminal 140 _n constitutes an effective user in step 212. If the mobile terminal is configuring an effective user, the authentication server 150 responds to the mobile terminal 140 _n at step 214 using the Wired Equivalent Privacy (WEP) encryption key, which device may be configured by the browser software of the device. Activate the WEP encryption key through the ActiveX command in the ActiveX control. ActiveX controls are essentially executable programs that can be embedded within web pages. Many software browser programs, such as Microsoft Internet Explorer, can display such web pages and launch embedded ActiveX controls that can be downloaded from a remote server (eg, authentication server 150). Execution of ActiveX controls is limited by the security mechanisms configured in the browser software. Indeed, most browser software has several different levels of security to choose from. At the lowest level, any ActiveX control from the web can start without restriction. At the highest level, there is no ActiveX control that can be launched from browser software.

The method according to the invention comprises, in step 217 after authentication and authorization, generating a first key and distributing the new key to the access point 130 _n and the mobile terminal 140 _n . In step 221, the second key, referred to as the security seed 123, is distributed to the mobile terminal 140 _n and the access point 130 _n . Thereafter, the mobile terminal and the access point communicate using the first key as a session for encrypting data. Thereafter, the access point 130 _n and the mobile terminal 140 _n periodically adopt a key 119 and a security seed 123 to periodically generate a new session key 121, whereby the new session key is moved. Used for subsequent communication between the terminal and the access point. The second key is always stored and kept secret at the mobile terminal and the access point during the communication session, so that the hacker cannot determine the second key. Prior to generating a new session key and using that new key for security, some techniques may be employed that make it easier to manage the combined key, such as associating the new session key with the security seed. By associating the combined session key with the secure seed, the process may calculate a hash algorithm for the associated new session key and secure seed and generate a fixed string for transmission.

A method for improving the security of a mobile terminal in a WLAN environment is that the mobile terminal 140 _n sends an encrypted logoff request performed by the secure seed during session logoff so that the secure seed requests the logoff request. It further comprises the step of appearing in. During session logoff, the mobile terminal 140 _n maintains a secure state that prevents hackers from logging off the authenticated mobile terminal 140 _n . IEEE 802.1x based schemes cannot provide secure logoff because the logoff request is performed in an unencrypted frame. However, in the embodiment of the present invention, mobile terminal 140 _n transmits an encrypted log off request 228 performed by secure seed 123. So even if the hacker cracks the session key, the logged off of the authenticated user to the mobile terminal 140 _n is not possible because the security seed 123 appears in the log off request 228, and the user logs This is because the new security seed is no longer used after the new security seed needs to be negotiated every time.

4 shows an apparatus for a secure communication session between mobile terminal 140 _n and a WLAN. The access point 130 _n includes means 410 for generating first and second security keys, and transmitting the first security key 119 and the second security key 123 to the mobile terminal 140 _n . And means 420 for. Mobile terminal 140 _n receives first security key 119 and second security key 123 and stores the key in register 430 for use during secure communication. Access point 130 _n includes means for encrypting data 415 and means 420 for transmitting data to mobile terminal 140 _n over WLAN 115 using the current session key. The mobile terminal 140 _n includes means for receiving 450 and means 435 for decrypting data received from the access point 130 _n using the current session key, the first security key being Initially, it is used as the current session key 119. The access point 130 _n includes means 425 for periodically generating a subsequent session key using the second session key, and during subsequent communication between the WLAN 115 and the mobile terminal 140 _n , the subsequent session key Is used as the current session key.

The form of the invention as shown is to be understood merely as a preferred embodiment. Various modifications may be made in the function and arrangement of the components, and equivalent means may be substituted for the illustrated and described means, and certain features are independent of the other features without departing from the spirit and scope of the invention as defined in the following claims. It can also be used.

Claims (23)

A method for providing a secure communication session with a user terminal in a communication network, the method comprising: The method, Transmitting a first and a second security key to the user terminal using a secure communication method, the first and second security keys suitable for storage in the user terminal for use during the secure communication session; Encrypting and transmitting data to the user terminal using a current session key, and receiving and decrypting data received from the user terminal using the current session key—the first security key is initially used for the current session. Used as a key, and Periodically generating a subsequent session key using the second security key, and using the subsequent session key as a current session key during subsequent communication between the communication network and the user terminal. Communication session providing method comprising a. The method of claim 1, And logging off the user terminal in response to an encrypted logoff request from the user terminal performed by the second security key. The method of claim 1, And said periodically generating step comprises associating said current session key with said second security key and generating said subsequent session key by applying a hash algorithm. A method for providing a secure communication session with a mobile terminal in a wireless local access network (WLAN), The method, Transmitting a first and second security key to the mobile terminal using a secure communication method, the first and second security keys suitable for storage in the mobile terminal for use during the secure communication session; Encrypting and transmitting data to the mobile terminal using a current session key, and receiving and decrypting data received from the mobile terminal using the current session key, wherein the first security key is initially used for the current session. Used as a key, and Periodically generating a subsequent session key using the second security key, and using the subsequent session key as the current session key during subsequent communication with the mobile terminal. Communication session providing method comprising a. The method of claim 4, wherein Wherein the periodic generating step comprises generating a subsequent session key using a combination of a new key generated using the first security key and the second security key. The method of claim 5, And said periodically generating step comprises generating a subsequent session key by associating said new key with said second security key and operating a hash algorithm to generate a subsequent session key. A method for providing a secure communication session with a mobile terminal in a wireless local access network (WLAN), The method, Generating a security key, Transmitting the security key to the mobile terminal using a secure communication method, the security key being stored in the mobile terminal for use during the secure communication session; Encrypting and transmitting data to the mobile terminal using a current session key, receiving and decrypting data received from the mobile terminal using the current session key, and Terminating the secure communication session in response to receiving a logoff message from the mobile terminal, wherein the logoff message is in encrypted form and includes the security key. Communication session providing method comprising a. A method for providing a secure communication session with a mobile terminal in a wireless local access network (WLAN), The method, Generating first and second security keys, Transmitting the first and second security keys to the WLAN using the secure communication method, wherein the first and second security keys are stored in the WLAN for use during the secure communication session; Encrypting and transmitting data to the WLAN using a current session key, and receiving and decrypting data received from the WLAN using the current session key, wherein the first security key is initially used as the current session key. Used-, and Periodically generating a subsequent session key using the second security key, and using the subsequent session key as the current session key during subsequent communication with the mobile terminal. Communication session providing method comprising a. The method of claim 8, Wherein the periodic generating step comprises generating a subsequent session key using a combination of a new key generated using the first security key and the second security key. The method of claim 9, And said periodically generating step comprises generating a subsequent session key by associating said new key with said second security key and operating a hash algorithm to generate a subsequent session key. A method for providing a secure communication session with a mobile terminal in a wireless local access network (WLAN), The method, Generating a security key, Transmitting the security key to the WLAN using the secure communication method, the security key being stored in the WLAN for use during the secure communication session; Encrypting and transmitting data to the WLAN using a current session key, receiving and decrypting data received from the WLAN using the current session key, and Terminating the secure communication session in response to receiving a logoff message from the WLAN, wherein the logoff message is in encrypted form and includes the security key. Communication session providing method comprising a. A method for providing a secure communication session with a mobile terminal in a wireless local access network (WLAN), The method, Installing at least two shared secrets on both the mobile terminal and the WLAN access point during a user authentication step, whereby the first secret is an initial session key and the second secret generates a subsequent session key. A method of providing a communication session for use as a service. The method of claim 12, Generating a new key, encrypting the new key using a current key, and exchanging the new key between the WLAN and the mobile terminal. The method of claim 12, Generating a new session key by the WLAN and the mobile terminal employing the new session key and the secure seed. The method of claim 14, Generating a new session key comprises associating the new key with the secure seed. The method of claim 15, Generating a new session key by applying a hash algorithm to the associated result. The method of claim 16, Using the new session key in communication between the WLAN and the mobile terminal. A method for providing a secure communication session between a mobile terminal and a wireless local access network (WLAN), the method comprising: The method, Sending, by the mobile terminal, an encrypted log off request carrying a secure seed during the session log off, causing the secure seed to appear in the log off request. An access point for providing a secure communication session between a mobile terminal and a wireless local access network (WLAN), Means for transmitting first and second security keys to the mobile terminal using a secure communication method, and Means for encrypting data using the first security key and means for periodically generating a subsequent session key using the second security key. Access point comprising a. A terminal device for providing a secure communication session to a communication network, comprising: Means for receiving a first security key and a second security key, means for storing the first security key and the second security key for use during the secure communication session; Means for receiving data and means for decrypting data using a current session key during the secure communication session, wherein the first security key is initially used as the current session key, and Means for generating a subsequent session key using the current session key and the second security key, the subsequent session key subsequently using as the current session key for subsequent communication. Terminal device comprising a. The method of claim 20, The terminal device comprises a mobile terminal and the communication network comprises a wireless local access network (WLAN). An access point for providing a secure communication session between a mobile terminal of claim 20 and a wireless local access network (WLAN), And said means for periodically generating a subsequent session key comprises means for generating a subsequent session key using a combination of the new key and the second security key generated by the means using the first security key. . An access point for providing a secure communication session between a mobile terminal of claim 20 and a wireless local access network (WLAN), The means for periodically generating a subsequent session key includes means for generating a subsequent session key by associating the new key with the second security key, and means for operating a hash algorithm for generating the subsequent session key. Access point.