CN101267670B

CN101267670B - An initialization setup method for secret key survival counter between different access systems

Info

Publication number: CN101267670B
Application number: CN200810066802A
Authority: CN
Inventors: 张旭武; 甘露
Original assignee: ZTE Corp
Current assignee: Xuzhou Naili Macromolecule Technology Co Ltd
Priority date: 2008-04-15
Filing date: 2008-04-15
Publication date: 2012-09-05
Anticipated expiration: 2028-04-15
Also published as: CN101267670A

Abstract

A method for initializing and setting key survival counters between different access systems. When a user equipment moves from an evolved terrestrial wireless access network to a terrestrial wireless access network and needs to perform cell reselection, the following steps are performed: the When the user equipment decides to reselect the cell to the UMTS network, it will add at least 1 to the effective value of the high bit of the counter COUNT _- NAS as the initial value of the counter START, and then send a cell reselection request to the target serving UMTS network; wherein, the counter START is the terrestrial radio The survival counter of the integrity key IK and the encryption key CK of the access network, the counter COUNT _-NAS is to record the integrity protection key K _NAS-int and confidentiality of the non-access stratum of the evolved terrestrial wireless access network Protection key K A counter of the number of network access server signalings protected by _NAS-enc . The present invention can avoid the safety loophole that the key lifetime is prolonged when UE moves between UTRAN and EUTRAN and initiates cell reselection.

Description

The initial setting method that is used for cryptographic key existence counter among different access systems

Technical field

The present invention relates to moving communicating field, relate in particular to a kind of method that the cryptographic key existence counter among different access systems initialization is provided with that is used for.

Background technology

3GPP (3rd Generation Partnership Project; Third generation partner program) grouping system of evolution (Evolved Packet System; Be called for short EPS) by land radio access web (the Evolved UMTS Terrestrial Radio Access Network of evolution; Be called for short EUTRAN) and EPS core net (Evolved Packet Core is called for short EPC) composition.

Wherein, EPC comprises mobile management unit (MME, Mobility Management Entity), and mobile management unit is responsible for the processing of ambulant management, Non-Access Stratum signaling and the chain of command related works such as management of user security model.Wherein, MME preserves the root key K of EUTRAN _ASME(Key Access Security Management Entity, the secret key of access security management entity), and by K _ASMEThe Non-Access Stratum integrity protection key K that generates _NAS-int(Key Non Access Stratum integrity) and Confidentiality protection key K _NAS-enc(Key Non Access Stratum encryption).Also in store these three keys of while UE (User Equipment, subscriber equipment).Also there is a counter COUNT among UE and the MME _-NAS, responsible record has received key K _NAS-intAnd K _NAS-encNAS (Network Access Server, network access server) the signaling quantity of protection.COUNT _-NASValue two effects are arranged, one is the input parameter that is used for doing NAS layer integrity protection and Confidentiality protection, another one is to be used for strict restriction key K _ASMELife span, work as COUNT _-NASValue arrive family of power and influence's value that operator sets, UE and network side will trigger new Authentication and Key Agreement machine-processed (AKA, Authentication and key agreement) and produce new K _ASME, all EPS counters are changed to 0 simultaneously.When connecting, UE and MME use START _-NASValue come recording counter COUNT _-NASHigh Bit Significance.UE uses START _-NASCome count initialized device COUNT _-NAS, be about to START _-NASValue as COUNT _-NASThe value of high-order effective bit (MSB:Most Significance Bit, its concrete figure place is by standard definition) be high Bit Significance, break off when connecting, UE uses COUNT _-NASThe value of high-order effective bit upgrade START _-NASValue.

3GPP UMTS (Universal Mobile Telecommunications System; UMTS) equipment of the management of responsible contextual management of mobility and/or user security model is SGSN (Serving GPRS Support Node, Serving GPRS Support Node) in the system.SGSN also is responsible for authentication UE, and generates key IK (Integrity Key, Integrity Key), CK (Ciphering Key, encryption key).The connecting system of 3GPP UMTS system is UTRAN (UMTS Terrestrial Radio Access Network, a wireless access network).

UE also generates IK, CK simultaneously.In the PS territory, UE usage counter START record receives the signaling quantity of key IK and CK protection, when the family of power and influence who arrives setting when the value of START is worth; Make new AKA with triggering UE and SGSN, produce new IK, CK; The START value puts 0 simultaneously; Therefore at UMTS, counter START is the existence counter of key IK and CK, and its strictness has limited the life span of key.When connecting; UE and RNC (radio network controller; Radio Network Controller) or SGSN use the value of START to be used for the value of high-order effective bit of count initialized device COUNT-I and COUNT-C; When breaking off connection, UE uses the value of the high-order effective bit of COUNT-I and COUNT-C to upgrade the value of START.Wherein counter COUNT-I is the counter of network access server signaling quantity that writes down the Integrity Key IK protection of the land radio access web that receives evolution, and COUNT-C is the counter of network access server signaling quantity that writes down the encryption key IK protection of the land radio access web that receives evolution.

When UE moved to EUTRAN from UTRAN, UE and MME used IK and CK to produce K _-ASME, use COUNT simultaneously _-NASBe K _-ASMEExistence counter, IK and CK are called K _-ASMEFather's key, K _-ASMEThen be called CK, the sub-key of IK.When UE when EUTRAN transfers to UTRAN, UE and SGSN/RNC use K _-ASMEProduce key IK and CK, use START to limit CK simultaneously, the life span of IK, K _-ASMEThe father's key that is called IK and CK, IK and CK are K _-ASMESub-key.

Owing to when UE carries out district reselecting (TAU, Tracking Area Update) between UTRAN and EUTRAN, do not have mandatory requirement to reuse AKA and carry out key updating, the sub-key that is produced by father's key may continue to use a period of time.

In the prior art; Between UTRAN and EUTRAN during district reselecting; The UE counter is not continued each other and add up, but directly the counter initial value is set to 0, so that behind the TAU; The life span that does not comprise his father's key the life cycle of key, the security breaches that cause key lifetimes to be extended.

Summary of the invention

The present invention provides a kind of initial setting method that is used for cryptographic key existence counter among different access systems, when initiating district reselecting to avoid UE between UTRAN and EUTRAN, to move, and the security breaches that key lifetimes is extended.

In order to solve the problems of the technologies described above; The present invention also provides a kind of initial setting method that is used for cryptographic key existence counter among different access systems; It is characterized in that; Subscriber equipment from the land radio access web of evolution landwards wireless access network move, in the time of need carrying out district reselecting, carry out following steps:

When said subscriber equipment decision district reselecting arrives the UMTS network, with counter COUNT _-NASHigh Bit Significance add 1 initial value at least as counter START; Then, send cell re-selection request and give destination service UMTS network;

Wherein, counter START is the Integrity Key IK of land radio access web and the existence counter of encryption key CK, counter COUNT _-NASIt is the Non-Access Stratum integrity protection key K that writes down the land radio access web that receives evolution _NAS-intWith the Confidentiality protection key K _NAS-encThe counter of the network access server signaling quantity of protection.

Further, said method also can have following characteristics:

Said subscriber equipment is earlier with counter COUNT _-NASHigh Bit Significance add 1 at least after, compose to give counter START _-NAS, the value initialization with counter START is counter START then _-NASValue; Counter START wherein _-NASBe to be used for recording counter COUNT _-NASThe counter of high Bit Significance.

Further, said method also can have following characteristics:

Said subscriber equipment is earlier with counter COUNT _-NASHigh Bit Significance add 2 after, compose to give counter START _-NASValue initialization with counter START is counter START then _-NASValue, i.e. START=START _-NAS=MSB (COUNT _-NAS)+2; Counter START wherein _-NASBe to be used for recording counter COUNT _-NASThe counter of high Bit Significance, said MSB is high Bit Significance.

Further, said method also can have following characteristics:

Said UMTS network sends context request to source mobile management unit after receiving that said subscriber equipment sends cell re-selection request; After said source mobile management unit is received, send context response to said UMTS network; The UMTS network sends district reselecting to said subscriber equipment again to be confirmed, notifies its network acceptance area reselection request; Said subscriber equipment sends district reselecting to the target mobile management unit and accomplishes message, and the affirmation district reselecting is accomplished.

Further, said method also can have following characteristics:

In the process that the RRC that said subscriber equipment is initiated after district reselecting is accomplished connects; Said subscriber equipment and said UMTS network come count initialized device COUNT-I, COUNT-C with said START value again; Wherein COUNT-I is the counter of network access server signaling quantity that writes down the Integrity Key IK protection of the land radio access web that receives evolution, and COUNT-C is the counter of network access server signaling quantity that writes down the encryption key CK protection of the land radio access web that receives evolution.

The method of the invention is owing to adopt START and START _-NASContinue, and come the initialization associated counter, overcome in the prior art UE between UTRAN and EUTRAN during TAU, the safety defect that the key life cycle is extended with it.

Description of drawings

Fig. 1 moves to EUTRAN when carrying out TAU from UTRAN, the signaling process figure of UE counter initial setting method for embodiment of the invention UE;

Fig. 2 moves to UTRAN when carrying out TAU from EUTRAN, the signaling process figure of counter initial setting method for another embodiment of the present invention UE.

Embodiment

Design of the present invention is: UE moves between different access systems; In the time of district reselecting need being carried out, utilize the START value in the former connecting system, the START value in the initialization goal systems; And when connecting, use the counter in the START value initialization goal systems in the goal systems.

Aim to provide a kind of after UE carries out the TAU between UTRAN and the EUTRAN; The initial method of counter; Make the sub-key life cycle continue the life span of the preceding his father's key of TAU; And after the TAU success, continue the life span of sub-key that adds up, thereby avoid the life span of sub-key to be extended.

Below in conjunction with accompanying drawing and embodiment technical scheme according to the invention is described in detail.

First embodiment

Present embodiment be UE under idle condition, move to EUTRAN from UTRAN, in the time of need carrying out district reselecting, counter is carried out the method that initialization is provided with.Its signaling process is as shown in Figure 1, may further comprise the steps:

Step 101:UE is to START _-NASCarry out the initialization setting, make START _-NAS=START uses START then _-NASTo COUNT _-NASCarry out the initialization setting;

To COUNT _-NASWhen carrying out initialization and being provided with, be about to START _-NASValue as COUNT _-NASThe value of high-order effective bit, can be expressed as MSB (COUNT with formula _-NAS)=START _-NAS, COUNT _-NASAll the other bit positions be 0.

UE also need use IK and CK to generate K in this step _-ASME, K _NAS-intAnd K _NAS-enc, because need in follow-up TAU request, use this key to carry out integrity protection.

Step 102:UE sends out the TAU request to target MME, simultaneously with START _-NASIssue target MME;

Step 103: target MME sends out context request to source SGSN, and request source SGSN transmits IK, user profile such as CK;

Step 104: source SGSN sends out context response to target MME, and with CK, user related informations such as IK are passed to target MME;

Step 105: target MME uses START _-NASTo COUNT _-NASCarry out the initialization setting;

Here target MME also uses IK and CK to generate K _-ASME, K _NAS-intAnd K _NAS-enc, be used for the encipherment protection of subsequent message.

Step 106: target MME notifies UE, and TAU is accepted;

Step 107:UE sends out TAU and accomplishes message, confirms that TAU accomplishes.

Second embodiment

Present embodiment be UE under idle condition, move from EUTRAN and UTRAN, in the time of need carrying out TAU, counter is carried out the method that initialization is provided with.As shown in Figure 2, may further comprise the steps:

When step 201:UE decision district reselecting arrives the UMTS network, use COUNT _-NASThe START of value initialization with START is set _-NAS, be about to COUNT _-NASThe value (being also referred to as high Bit Significance) of high-order effective bit add that 2 (also can add and be no less than other integers of 1) backs composes and give START here _-NAS, can be expressed as START _-NAS=MSB ₂₀(COUNT _-NASInitialization, START=START are carried out to START simultaneously in)+2 _-NAS

Step 202:UE sends out TAU and asks target SGSN;

Step 203: target SGSN send out context request to the source MME;

Step 204: source MME sends out context response to target SGSN;

Step 205: target SGSN is sent district reselecting to UE and is confirmed that notice UE network has been accepted TAU;

Step 206:UE sends out TAU and accomplishes acknowledge message.

When district reselecting, SGSN does not carry out the initialization setting to START, and after UE initiated the RRC connection, UE and SGSN used the COUNT-I of START value initialization, COUNT-C again.

From foregoing description, owing to adopt START and START _-NASContinue, and come the initialization associated counter, overcome in the prior art UE between UTRAN and EUTRAN during TAU, the safety defect that the key life cycle is extended with it.

The above is merely embodiments of the invention, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.All within spirit of the present invention and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within the claim scope of the present invention.

Claims

1. A method for initializing a key survival counter between different access systems, characterized in that, when a user equipment moves from an evolved terrestrial wireless access network to a terrestrial wireless access network and needs to perform cell reselection, Perform the following steps:

When the user equipment decides to reselect the cell to the UMTS network, it adds at least 1 to the high effective value of the counter COUNT _-NAS as the initial value of the counter START; then, sends a cell reselection request to the target serving UMTS network;

Among them, the counter START is the survival counter of the integrity key IK and the encryption key CK of the terrestrial wireless access network, and the counter COUNT _-NAS is the record that has been protected by the integrity protection key of the non-access stratum of the evolved terrestrial wireless access network A counter of the number of network access server signaling protected by K _NAS-int and the confidentiality protection key K _NAS-enc .

2. The initialization setting method as claimed in claim 1, characterized in that:

The user equipment first adds at least 1 to the high effective value of the counter COUNT _-NAS , then assigns it to the counter START _-NAS , and then initializes the value of the counter START to the value of the counter START _-NAS ; wherein the counter START _-NAS is used for A counter that records the high effective value of the counter COUNT _-NAS .

3. The initialization setting method as claimed in claim 1 or 2, characterized in that:

The user equipment first adds 2 to the high-order effective value of the counter COUNT _-NAS , and assigns it to the counter START _-NAS ; then initializes the value of the counter START to the value of the counter START _-NAS , that is, START=START _-NAS =MSB( COUNT _-NAS )+2; wherein the counter START _-NAS is a counter for recording the high-order effective value of the counter COUNT _-NAS , and the MSB is the high-order effective value.

4. The initialization setting method as claimed in claim 1 or 2, characterized in that:

After the target serving UMTS network receives the cell reselection request sent by the user equipment, it sends a context request to the source mobility management unit; after the source mobility management unit receives it, it sends a context response to the target serving UMTS network; The target serving UMTS network then sends a cell reselection confirmation to the user equipment, notifying the network that the cell reselection request has been accepted; the user equipment sends a cell reselection complete message to the target mobility management unit, confirming that the cell reselection has been completed.

5. The initialization setting method as claimed in claim 1 or 2, characterized in that:

During the RRC connection initiated by the user equipment after cell reselection is completed, the user equipment and the target serving UMTS network use the START value to initialize counters COUNT-I and COUNT-C, wherein COUNT-I is a counter that records the number of network access server signaling that has been protected by the integrity key IK of the evolved terrestrial wireless access network, and COUNT-C is a record that has been protected by the encryption key CK of the evolved terrestrial wireless access network A counter of the number of network access server signaling.