Method and system of secured direct link set-up (DLS) for wireless networks

Abstract

Method and system of secured direct link set-up (DLS) for wireless networks. In accordance with aspects of the method, techniques are disclosed for setting up computationally secure direct links between stations in a wireless network in a manner that is computationally secure. A direct link comprising a new communication session is set up between first and second stations in a wireless local area network (WLAN) hosted by an access point (AP), the direct link comprising a new communication session. The AP generates a unique session key for the new communication session and transfers secured copies of the session key to each of the first and second stations in a manner under which only the first and second stations can obtain the session key. A security mechanism is then implemented on the unsecured direct link to secure the direct link between the first and second stations using a secure session key derived from the session key.

1 . A method comprising: 
 setting up a direct link between first and second stations in a wireless local area network (WLAN) hosted by an access point (AP), the direct link comprising a new communication session;    generating, at the AP, a session key unique to the new communication session;    transferring copies of the session key to each of the first and second stations in a manner under which only the first and second stations can obtain the session key; and    implementing a security mechanism for the direct link to effect a secure direct link employing a secure session key derived from the session key.    
     
     
         2 . The method of  claim 1 , wherein each of the access point and the first and second stations support quality of service facilities defined by the IEEE 802.11e/D13 draft Standard, and the direct link comprises a DLS link set up using the Direct Link Set-up (DLS) protocol.  
     
     
         3 . The method of  claim 1 , further comprising: 
 setting up a first (Robust Security Network Association (RSNA) link between the first station and the AP, set up of the first RSNA link including a first key exchange between the first station and the AP; and    setting up a second RSNA link between the second station and the AP, set up of the second RSNA link including a second key exchange between the second station and the AP.    
     
     
         4 . The method of  claim 1 , further comprising: 
 generating first and second Pairwise master keys;    passing the first and second Pairwise master keys to the first and second stations, respectively;    deriving a first Key Encryption Key (KEK) from the first Pairwise master key at each of the first station and the AP;    deriving a second KEK from the second Pairwise master key at each of the second station and the AP    encrypting a first copy of the session key using the first KEK and sending a first message containing the encrypted first copy of the symmetric session key from the AP to the first station;    encrypting a second copy of the session key using the second KEK and sending a second message containing the encrypted second copy of the session key from the AP to the second station;    employing, at the first station, the first KEK to decrypt the first message to extract the first copy of the session key;    employing, at the second station, the second KEK to decrypt the first message to extract the second copy of the session key.    
     
     
         5 . The method of  claim 4 , further comprising: 
 passing information identifying a key wrap algorithm employed to encrypt the first and second copies of the session key to the first and second stations; and employing the key wrap algorithm at the first and second stations to decrypt encrypted wrappers containing the first and second copies of the session key.    
     
     
         6 . The method of  claim 1 , further comprising: 
 generating first and second Key Conformation Keys (KCKs);    passing the first and second KCKs from the AP to the first and second stations, respectively;    encapsulating a first copy of the session key in a first message containing a first security string and a hash of the first security string, the hash of the first security string employing the first KCK;    encapsulating a second copy of the session key in a second message containing a second security string and a hash of the second security string, the hash of the second security string employing the second KCK;    sending the first and second messages from the AP to the first and second stations, respectively;    employing, at the first station, the first KCK to authenticate the first message by performing a hash on the first security string using the first KCK and comparing the result with the hash of the first security string contained in the first message; and    employing, at the second station, the second KCK to authenticate the second message by performing a hash on the second security string using the second KCK and comparing the result with the hash of the second security string contained in the second message.    
     
     
         7 . The method of  claim 6 , further comprising: 
 passing information to the first and second stations identifying a Message Integrity Code (MIC) algorithm employed to performing the hashes on the first and second security strings contained in the first and second messages; and    employing the MIC algorithm at the first and second stations to hash the first and second security strings contained in the first and second messages in connection with authenticating the first and second messages.    
     
     
         8 . The method of  claim 1 , further comprising: 
 generating a first random number at the first station;    generating a second random number at the second station;    transferring the first and second random numbers to the AP; and    employing the first random and second random numbers to generate a key name associated with the session key.    
     
     
         9 . The method of  claim 1 , further comprising: 
 generating, at the AP, a key name to be associated with the session key;    providing a copy of the key name to each of the first and second stations;    performing a four-way handshake using the session key as a Pairwise master key and the key name as a key identifier; and    deriving a Pairwise Transient Key from the session key, the Pairwise Transient Key used as the secure session key.    
     
     
         10 . The method of  claim 1 , further comprising: 
 generating a first random number at the first station;    transferring the first random number in a message to the second station to request setting up a secure direct link between the first station and the second station;    transferring the first random number from the second station to the AP;    embedding the first random number in a message sent from the AP to the first station in conjunction with setting up a secure direct link between the first station and the second station, the first random number used to correlate the message sent from the AP with the request to set up the secure direct link between the first station and the second station.    
     
     
         11 . A wireless access point (AP), comprising: 
 a radio frequency (RF) interface, transmit and receive RF signals corresponding to a wireless communications protocol;    a processor coupled to the RF interface; and    logic implemented via at least one of embedded logic and execution of machine instructions stored on the AP and executed by a processor to perform operations including: 
 generating first and second keys and passing the first and second keys to first and second stations in a wireless local area network (WLAN) hosted by the AP;  
 performing AP-side operations to facilitate setting up a direct link between the first and second stations, the direct link comprising a new communication session;  
 generating a session key unique to the new communication session;  
 generating a first message including a first encrypted copy of the session key, the first encrypted copy generated using an encryption algorithm employing an encryption parameter comprising one of the first key or a value derived thereform;  
 generating a second message including a second encrypted copy of the session key, the second encrypted copy generated using encryption  
 algorithm employing an encryption parameter comprising one of the second key or a value derived thereform; and  
 sending the first and second messages to the first and second stations, respectively.  
   
     
     
         12 . The wireless AP of  claim 11 , wherein each of the AP and the first and second stations support quality of service facilities defined by the IEEE 802.11e/D13 draft Standard, and the direct link comprises a DLS link set up using the Direct Link Set-up (DLS) protocol.  
     
     
         13 . The wireless AP of  claim 11 , wherein the logic further performs AP-side operations to facilitate setting up of Robust Security Network Association (RSNA) links between the AP and each of the first and second stations, and wherein the first and second keys comprise first and second Pairwise master keys that are passed to the first and second stations in connection with set up of their respective RSNA links, and wherein the encryption parameters comprise Key Encryption Keys derived from the first and second Pairwise master keys.  
     
     
         14 . The wireless AP of  claim 11 , wherein the logic further performs operations comprising: 
 sending messages to each of the first and second stations containing an identifier for the encryption algorithm used for encrypting the session key.    
     
     
         15 . The wireless AP of  claim 11 , wherein the logic further performs operations comprising: 
 passing information identifying a Message Integrity Code (MIC) algorithm to be employed as a hashing function to the first and second stations;    generating a first security string comprising an encrypted session key and a hash of the first security string generated using the MIC algorithm;    generating a second security string comprising an encrypted session key and a hash of the first security string generated using the MIC algorithm;    including the first security string and the hash of the first security string in the first message; and    including the second security string and the hash of the second security string in the second message.    
     
     
         16 . The wireless AP of  claim 15 , wherein the each of the first and second security strings includes respective first and second identifiers generated by the first and second stations and received by the wireless AP in connection with setting up a secure direct link.  
     
     
         17 . A machine-readable medium, to provide instructions to be executed on a wireless access point (AP) to perform operations comprising: 
 generating first and second keys and passing the first and second keys to first and second stations in a wireless local area network (WLAN) hosted by the AP;    performing AP-side operations to facilitate setting up a direct link between the first and second stations, the direct link comprising a new communication session;    generating a session key unique to the new communication session;    generating a first message including a first encrypted copy of the session key, the first encrypted copy generated using an encryption algorithm employing an encryption parameter comprising one of the first key or a value derived thereform;    generating a second message including a second encrypted copy of the session key, the second encrypted copy generated using an encryption algorithm employing an encryption parameter comprising one of the second key or a value derived thereform; and    sending the first and second messages to the first and second stations, respectively.    
     
     
         18 . The machine-readable medium of  claim 17 , wherein each of the AP and the first and second stations support quality of service facilities defined by the IEEE 802.11e/D13 draft Standard, and the direct link comprises a DLS link set up using the Direct Link Set-up (DLS) protocol.  
     
     
         19 . The machine-readable medium of  claim 17 , wherein execution of the instructions perform further operations comprising: 
 performing AP-side operations to facilitate setting up Robust Security Network Association (RSNA) links between the AP and each of the first and second stations, and wherein the first and second keys comprise first and second Pairwise master keys that are passed to the first and second stations in connection with set up of their respective RSNA links, and wherein the encryption parameters comprise Key Encryption Keys derived from the first and second Pairwise master keys.    
     
     
         20 . The machine-readable medium of  claim 17 , wherein execution of the instructions perform further operations comprising: 
 sending messages to each of the first and second stations containing an identifier for the encryption algorithm used for encrypting the session key.    
     
     
         21 . The machine-readable medium of  claim 17 , wherein execution of the instructions perform further operations comprising: 
 passing information identifying a Message Integrity Code (MIC) algorithm to be employed as a hashing function to the first and second stations;    generating a first security string comprising an encrypted session key and a hash of the first security string generated using the MIC algorithm;    generating a second security string comprising an encrypted session key and a hash of the first security string generated using the MIC algorithm;    including the first security string and the hash of the first security string in the first message; and    including the second security string and the hash of the second security string in the second message.    
     
     
         22 . A machine-readable medium, to provide instructions to be executed on a first station in a wireless local area network (WLAN) hosted by a wireless access point (AP) to perform operations comprising: 
 receiving a first key from the AP;    generating a Key Encryption Key (KEK) from the first key;    performing station-side operations to set up a direct link between the first station and a second station in the WLAN;    submitting a request to set up a secure direct link;    receiving a message from the AP containing an session key that was encrypted using an encryption algorithm employing the KEK as a parameter;    extracting the session key from the message using a decryption algorithm associated with the encryption algorithm and employing the KEK as a parameter; and    negotiating a Pairwise Transient Key (PTK) with the second station to be employed to facilitate a secured direct link, the PTK derived from the session key.    
     
     
         23 . The machine-readable medium of  claim 22 , wherein execution of the instructions performs further operations comprising: 
 generating a random number;    including the random number in a secure link initiation request message;    extracting a message identifier from the message received from the AP; and    comparing the message identifier with the random number to verify the message is associated with the secure link request initiation message.    
     
     
         24 . The machine-readable medium of  claim 22 , wherein execution of the instructions perform further operations comprising: 
 performing station-side operations to facilitate setting up a Robust Security Network Association (RSNA) link between the station and the AP,    and wherein the first key comprises a Pairwise master key that is passed to the station in connection with setting up the RSNA links, and KCK is derived from the Pairwise master key.    
     
     
         25 . The machine-readable medium of  claim 22 , wherein each of the first station and the AP support quality of service facilities defined by the IEEE 802.11e/D13 draft Standard, and the direct link comprises a DLS link set up using the Direct Link Set-up (DLS) protocol.  
     
     
         26 . The machine-readable medium of  claim 17 , wherein execution of the instructions perform further operations comprising: 
 receiving information from the AP identifying a Message Integrity Code (MIC) algorithm to be employed as a hashing function in the message sent from the AP;    extracting a security string and the hash of the security string from the message sent from the AP;    employing an MIC algorithm identified by the information received from the AP to perform a hash on the security string; and    comparing the hash of the security string with the hash of the security string contained in the message to authenticate the message.