Method and system for generating an identifier of a key

• US 8,750,515 B2
• Filed: 06/15/2009
• Issued: 06/10/2014
• Est. Priority Date: 06/16/2008
• Status: Active Grant

• Current Assignee: ZTE Corporation
• Original Assignee: ZTE Corporation
• Inventors: Zhang, Xuwu, Huang, Qing
• Primary Examiner(s): GOLDBERG, ANDREW C
• Application Number:
  US12/997,253
• Publication Number:
  US 20110123029A1
• Time in Patent Office: 1,821 Days
• Field of Search: 380/272
• US Class Current: 380/272
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 2463/041 using an encryption or decryption engine integrated in transmitted data
• CPC Class Codes: H04L 2463/061 applying further key derivation, e.g. deriving traffic keys from a pair-wise master key cryptographic mechanisms or cryptographic arrangements for generation of secret information including derivation or calculation of cryptographic keys or passwords H04L9/0861
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04L 9/083 involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04W 12/041 Key generation or derivation
• CPC Class Codes: H04W 12/0471 Key exchange
• CPC Class Codes: H04W 36/0038 of security context information

Abstract

A method for generating an identifier of a key, comprises that: when a user equipment (UE) transfers from an evolved UMTS terrestrial radio access network (EUTRAN) to a universal terrestrial radio access network (UTRAN) or a global system for mobile communications (GSM), or an enhanced data rate for GSM evolved radio access network (GERAN), an identifier of a system key after transfer is generated by mapping an identifier KSI_ASME for an access security management entity, and a mobile management entity generates an identifier of a ciphering key (CK) and an integrity key (IK) by mapping the KSI_ASME, and then sends the generated identifier to a serving GPRS support node (SGSN), when the UE transfers from the EUTRAN to the UTRAN, the SGSN stores the ciphering key, the integrity key and the identifier thereof, and when the UE transfers from the EUTRAN to the GERAN, the SGSN assigns the value of the identifier of the ciphering key and the integrity key to an identifier of a ciphering key of the GERAN.

Claims

1. A method for generating an identifier of a key, comprising:

when a user equipment (UE) transfers from an evolved UMTS terrestrial radio access network (EUTRAN) to a universal terrestrial radio access network (UTRAN), a mobility management entity (MME) and the UE generating a key set identifier of a UTRAN system by mapping a key set identifier of an access security management entity key; and

the MME sending a serving GPRS support node (SGSN) the key set identifier of the UTRAN system, along with a ciphering key and an integrity key of the system;

wherein, the generation method of the mapping comprises;

the UE and the MME directly assign the value of the key set identifier of the UTRAN system to be the sum of the value of the key set identifier of the access security management entity key and a constant which is appointed by the UE and network side;

wherein when the UE transfers from the EUTRAN to the UTRAN in an idle state, after receiving a user information extraction request message sent by the UE to the SGSN, the MME generates an integrity key and a ciphering key using the key of the access security management entity, generates an identifier of the integrity key and the ciphering key, that is, a key set identifier, by mapping the key set identifier for the access security management entity, and sends the integrity key, the ciphering key and the key set identifier to the SGSN via a user information extraction response message; and

the SGSN stores the ciphering key, the integrity key and the key set identifier.

2. The method according to claim 1, wherein the request message sent by the UE to the SGSN for transferring to the UTRAN in an idle state is a routing area update request message;

correspondingly, the user information extraction request message is a context request message; and

the user information extraction response message is a context response.

3. The method according to claim 1, wherein the request message sent by the UE to the SGSN for transferring to the UTRAN in an idle state is an attachment request message;

correspondingly, the user information extraction request message is an identification request message; and

the user information extraction response message is an identification response.

4. The method according to claim 1, wherein after determining to transfer to the UTRAN in an idle state and before correspondingly sending the SGSN a message indicative of the completion of the transfer to the UTRAN in an idle state, the UE generates a key set identifier by mapping the key set identifier of the access security management entity key, and stores the key set identifier, along with the integrity key and the ciphering key which are generated from the key of the access security management entity.

5. The method according to claim 4, wherein the message sent by the UE to the SGSN for indicating the completion of the transfer to the UTRAN in an idle state is a routing area update completion message or an attachment completion message.

6. The method according to claim 1, wherein when the UE transfers from the EUTRAN to the UTRAN under the condition that a radio resource control (RRC) is in an active state, after receiving a handover request, the MME generates an integrity key and a ciphering key using the key of the access security management entity, generates an identifier of the integrity key and the ciphering key, that is, a key set identifier, by mapping the key set identifier of the access security management entity key, and sends the integrity key, the ciphering key and the key set identifier to the SGSN via a forward redirecting request message;

the SGSN stores the ciphering key, the integrity key and the key set identifier; and

after receiving a handover command sent by the network side, the UE generates a key set identifier by mapping the key set identifier of the access security management entity key and stores the key set identifier, along with the integrity key and the ciphering key which are generated from the key of the access security management entity.

7. The method according to claim 1, wherein if a key is associated by the network side and the UE before the UE transfers, and if the key set identifier associated before the transfer is the same as that of the system key which is generated by mapping the key set identifier of the access security management entity key during the transferring process, then the keys stored in the SGSN and the UE before the transfer are deleted.

8. A system for generating an identifier of a key, which is suitable for generating an identifier of a system key when a UE transfers from an EUTRAN to a UTRAN, comprising:

a user equipment (UE) UE, a mobility management entity (MME) and a serving GPRS support node (SGSN), wherein;

the UE is configured to map a key set identifier for an access security management entity into a key set identifier of a UTRAN system; and

the MME is configured to map a key set identifier for the access security management entity into a key set identifier of the UTRAN system and send the obtained identifier to the SGSN;

wherein, a mode of the mapping is as follows;

the UE and the MME directly assign the value of the key set identifier of the UTRAN system to be the sum of the value of the key set identifier of the access security management entity key and a constant which is appointed by the UE and a network side;

wherein, when the UE transfers from the EUTRAN to the UTRAN in an idle state, the MME is further configured to;

receive a user information extraction request message sent by the UE to the SGSN;

generate an integrity key and a ciphering key using the key of the access security management entity, and generate an identifier of the integrity key and the ciphering key, that is, a key set identifier, by mapping the key set identifier for the access security management entity; and

send the integrity key, the ciphering key and the key set identifier to the SGSN via a user information extraction response message; and

the SGSN is further configured to receive and store the ciphering key, the integrity key and the key set identifier.