CN1964253B

CN1964253B - A method to regenerate secret key after secret key polluted

Info

Publication number: CN1964253B
Application number: CN2005101156592A
Authority: CN
Inventors: 庄宏成; 杜汉美
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2005-11-09
Filing date: 2005-11-09
Publication date: 2010-07-21
Anticipated expiration: 2025-11-09
Also published as: CN1964253A

Abstract

The disclosed regeneration method for polluted key comprises: using multi-layer calculation to generate the original key, wherein generating next layer key according to current layer one; when detecting current polluted key, applying new key to last layer to generate new one with applied result. Thereby this invention can reduce time on key regeneration and the time delay, and decreases interaction times between STS and identification server in WLAN to prevent data loss.

Description

A kind of method of polluting the back regenerating key at key

Technical field

The present invention relates to communication and computer realm, relate in particular to a kind of method of polluting the back regenerating key at key.

Background technology

At present in the verification process of wireless lan (wlan), the generative process of key is divided into several levels.When certain one-level key is under attack, subordinate's key of key generation all will be polluted thus, and consequent session is with deleted.

As shown in Figure 1, after wireless site (STA) and certificate server have carried out the 802.1X authentication, can produce a master session key (MSK) (if adopt PSK, then disposing this PSK in advance on STA and network equipment), all have MSK on network side and the STA this moment.Network side pairwise master key R0 (PMK-R0) holder obtains this MSK, and generates PMK-R0 together with some other parameter by certain algorithm.Equally, network side R1 key holder obtains PMK-R0 from network side R0 key holder, and generates PMK-R1 together with some other parameter by certain algorithm.Last WAP (wireless access point) (AP) obtains PMK-R1.On terminal, STA generates PMK-R0 by MSK and some parameters by same algorithm, generates PMK-R1 then.STA and PMK-R1 carry out 4-Way Handshake then, PMK-R1 and some parameters generate identical new key PTK on STA and AP thus, if the two has identical PMK-R1,4-Way Handshake just can carry out so, if the PMK-R1 of the two is different, 4-Way Handshake can not carry out.

In the generative process of this key level, if middle certain one-level key is under attack, produce a contaminated key, so consequent subordinate key is all with contaminated, in this case, STA and certificate server need authenticate again to generate MSK (perhaps reconfiguring PSK).Time delay is bigger and authenticate again not only, and makes STA not carry out data communication with AP, thereby causes loss of data.

Summary of the invention

The invention provides and a kind ofly pollute the method for back regenerating key,, need authenticate again and have a problem that increases communication delay and obliterated data to solve prior art when the multilayer level generates that a certain level key is subjected to polluting in the cipher key processes at key.

The invention provides following technical scheme:

A kind of method at the back regenerating key of key pollution, described key generate after passing through the computing of multilayer level by initial key, and the key of every level is according to the key generation of last level; When being subjected to polluting, the key of determining current level carries out following step:

A, apply for key again to the last level of current level;

B, according to the new key of the newly-generated current level of key reconsul of applying for.

Also further comprise step after the step B:

C, determine whether new key identical with the original cipher key of current level,, determine that then the key of last level is contaminated if identical, with described last level as current level and carry out steps A; If different, determine that then new key is not comtaminated.

If unpolluted new key is the key of intermediate level, then generate the key of follow-up each level successively by level according to this new key.

In the steps A, before the application key, earlier judge whether current level is initial level, if then produce initial key again and utilize this initial key to generate the key of follow-up each level successively, otherwise a level is applied for key again forward by level.

Each level also adds the parameter of this level when generating key.

A kind of in the verification process of wireless lan (wlan) key pollute the method for back regenerating key, by generating pairwise master key R1 after master session key (MSK) or the computing of wildcard (PSK) process multilayer level, this pairwise master key R1 is PMK-R1, and the key of every level is by the key and the generation of this level parameter of last level; This method comprises the steps:

The failure of shaking hands of A, wireless site (STA) and access point (AP) determines that the PMK-R1 of network side is contaminated;

B, network side generate the level of PMK-R1 to the level application key that generates PMK-R0; The level of described generation PMK-R0 is the upper level of the level of described generation PMK-R1;

PMK-R0 and parameter that C, the utilization of described generation PMK-R1 level are applied for generate new PMK-R1;

D, with new PMK-R1 and former PMK-R1 relatively if both are identical, determines that then PMK-R0 is contaminated, then carries out step e, if inequality, AP then uses this PMK-R1;

E, apply for MSK or PSK to the holder of MSK or PSK, and itself and parameter are generated new PMK-R0 by the level that generates PMK-R0;

F, judge whether new PMK-R0 is identical with former PMK-R0, if then generate MSK or reconfigure PSK, and utilize this MSK or PSK to generate the key of follow-up each level successively by level by authentication again; If not, utilize PMK-R0 and parameter to generate new PMK-R1.

In network side regenerating key process, STA can communicate with other AP of network side.

When the present invention is subjected to polluting at intermediate level key, generates key by a level application key reconsul new key forward, thereby can reduce the time of regenerating key, reduce time delay; Especially in WLAN, can reduce the interaction times of STA and certificate server, thereby reduce data-bag lost.

Description of drawings

Fig. 1 be in the prior art among the 802.11r key generate level;

Fig. 2 is the handling process when key is subjected to polluting in the multilayer secondary key among the present invention;

Fig. 3 A, Fig. 3 B are respectively processing schematic diagram and the flow process when key is subjected to polluting in wlan system among the present invention.

Embodiment

Directly regenerate new initial key for fear of after the computing of multilayer level, generating in the final cipher key processes because of a certain level key in centre is contaminated by modes such as authentications at initial key, cause the time delay increase of communication and cause loss of data, when the present invention is subjected to polluting in intermediate key, be not subjected to polluting level application key to the front, regenerate the correct key of subordinate.

For current level key in an in the past level application to key and after generating the new key of this level, in order to determine whether last level key is polluted, the key of new key and this layer is compared, if both are identical, the key that last level then is described is polluted, therefore need regenerate new key to its last level application key by described last level, by that analogy, up to the level application of not polluted from the front to key.If determine that initial key is contaminated, then require to authenticate again to generate new initial key.

Consult shown in Figure 2ly, in communication process, the handling process when key is subjected to polluting is as follows:

The equipment of step 200, subscriber equipment and network side is mutual, generates initial key on subscriber equipment and network equipment; Perhaps on the equipment of subscriber equipment and network side, dispose initial key.

Step 210, subscriber equipment and network equipment utilize described initial key respectively, and computing generates the key of last level through the multilayer level; Wherein each level key is generated by previous stage key and this level parameter.

Step 220, subscriber equipment and network equipment reciprocal process are utilized the key authentication failure of described last level, and promptly the final key of terminal equipment and network side is inequality, determines that the key of the last level of network side is contaminated.

Step 230, by the level application and obtain key forward of current level.

The key that step 240, utilization are applied for and the parameter of current level generate new key by computing.

Step 250, judge whether new key is identical with the original cipher key of current level,, then carry out step 260 if identical, not inequality, then carry out step 300.

The key of step 260, the last level of explanation is contaminated, judges whether described last level is initial level, if then improve rapid 280 and 290, otherwise, carry out step 270.

Step 270, with described last level as current level, carry out step 230.

Step 280, subscriber equipment and certificate server are mutual, generate initial key on subscriber equipment and network equipment; Perhaps on subscriber equipment and network equipment, dispose initial key again.

Step 290, subscriber equipment and network equipment utilize described initial key respectively, and computing generates the key of last level through the multilayer level.

Step 295, if current level be last level, then use this level key; If current level is an intermediate level, then generate the key of follow-up each level successively by level according to this new key.

Above-mentioned level can be that the authenticate key of any communication network generates level, as the key level of WLAN.

Be that example further specifies with the level key among the WLAN below:

According to the generating algorithm of the key that defines in the existing 802.11r draft, the generation parameter of PMK-R0 and PMK-R1 is not at random, under the situation of parameter constant, algorithm by the key generation, the new key that its result promptly generates is also constant, promptly imports constantly, exports also constant.

By prior art, send both PMK-R1 when inequality when carrying out 4-Way Handshake between wireless site (STA) and the WAP (wireless access point) (AP), the PMD-R1 that determines network side generally speaking is contaminated, needs STA and certificate server to authenticate again to generate MSK; Or reconfigure PSK.But among the present invention, after PMK-R1 was polluted, directly the level that is not polluted from the higher level obtained key to generate the correct key of subordinate.Shown in Fig. 3 A and Fig. 3 B, its implementation procedure is as follows:

Step 300, STA and AP find when carrying out 4-Way Handshake that the PMK-R1 of the two is different, and 4-Way Handshake failure determines it may is that the key of AP network side has been subjected to pollution.

Step 310, apply for key PMK-R0 again to upper level R0 key holder by R1 key holder.

Key PMK-R0 and the newly-generated PMK-R1 of other parameter renegotiation that step 320, R1 key holder utilize R0 key holder to issue again.

Step 330, judge whether new PMK-R1 was identical with original PMK-R1,, determine it to be that PMK-R0 has been subjected to pollution, carry out step 340,, carry out step 400 if inequality if identical.

Step 340, R1 key holder notify R0 key holder key to be polluted, and R0 key holder asks MSK or PSK again to the holder of MSK or PSK.

After step 350, R0 key holder successfully obtain MSK or PSK, utilize this key to generate new PMK-R0.

Whether the new PMK-R0 that step 360, judgement generate is identical with original PMK-R0, if identical, may be that MSK or PSK have been subjected to pollution, carry out step 370, otherwise carry out step 390.

Step 370, initiate authentication again and generate MSK; Perhaps reconfigure PSK.

Step 380, R0 key holder utilize newly-generated MSK or PSK to generate new PMK-R0.

Step 390, R1 key holder utilize new PMK-R0 to generate new PMK-R1.

Step 400, AP use newly-generated PMK-R1.

To the process of step 400, STA can communicate with other AP in step 310.

Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims

1. one kind is polluted the method for back regenerating key at key, and described key is generated after through the computing of multilayer level by initial key, and the key of every level generates according to the key of last level; It is characterized in that, when the key of determining current level is subjected to polluting, carry out following step:

A, apply for key again to the last level of current level;

2. the method for claim 1 is characterized in that, if unpolluted new key is the key of intermediate level, then generates the key of follow-up each level successively by level according to this new key.

3. method as claimed in claim 1 or 2, it is characterized in that, in the steps A, before the application key, judge whether current level is initial level earlier, if, then produce initial key again and utilize this initial key to generate the key of follow-up each level successively, otherwise a level is applied for key again forward by level.

4. the method for claim 1 is characterized in that, each level also adds the parameter of this level when generating key.

5. the method for regenerating key after a kind key pollutes in the verification process of WLAN (wireless local area network) WLAN, by generating pairwise master key R1 after master session key MSK or the computing of wildcard PSK process multilayer level, this pairwise master key R1 is PMK-R1, and the key of every level is by the key and the generation of this level parameter of last level; It is characterized in that, comprise the steps:

A, wireless site STA and the access point AP failure of shaking hands determines that the PMK-R1 of network side is contaminated;

6. method as claimed in claim 5 is characterized in that, in network side regenerating key process, STA can communicate with other AP of network side.