WO2009143766A1

WO2009143766A1 - Method, system for distributing key and method, system for online updating public key

Info

Publication number: WO2009143766A1
Application number: PCT/CN2009/071979
Authority: WO
Inventors: 铁满霞; 曹军; 赖晓龙; 黄振海
Original assignee: 西安西电捷通无线网络通信有限公司
Priority date: 2008-05-26
Filing date: 2009-05-26
Publication date: 2009-12-03
Also published as: CN101286842A; CN101286842B

Abstract

A method for distributing key includes that: every time before performing a secret communication or when requiring to update a communication session key, a key distribution center receives a key request message sent by a entity, and generates a communication session key for using among entities, the communication session key is encrypted by using a temporary public key of the entity, and its signature is calculated by using a private key of the key distribution center, the signature and the encrypted communication session key are sent to the entity; after the entity receives the key response message, signature verification is performed by using the locally stored public key of the key distribution center; after signature verification has been passed, the communication session key is acquired by using decipherment of the temporary private key of the entity. The corresponding system for realizing key distribution, the system and method for online updating public key are provided by the invention. Safe distribution and dynamic updating of the communication key are realized by the invention, and online updating function of the public key of the forward secrecy support key distribution center is provided, furthermore, the reliability of communication security is improved.

Description

Method and system for key distribution and method and system for updating public key online This application claims to be submitted to the Chinese Patent Office on May 26, 2008, the application number is 200810018298.3, and the invention name is "a secret using public key cryptography technology". Priority of Chinese Patent Application for "Key Distribution and Its Public Key Online Update Method", the entire contents of which are incorporated herein by reference.

Technical field

The present invention relates to the field of information security technologies, and in particular, to a key distribution method and system, and a method and system for updating a public key online. Background technique

Key management is one of the key technologies when secure communication between communication network entities is required. Small networks can use a method of sharing a key for each pair of users, but not in large networks. A system with N users, in order to achieve secure communication between any two users, it is necessary to generate and allocate N (N-1) 12 keys to ensure secure communication between any two users in the network. As the size of the system increases, the complexity increases dramatically. For a network with N 1000, about 500,000 keys are needed for allocation, storage, and the like. In order to reduce the complexity, a centralized key management method is usually adopted, and a trusted online server is used as a key distribution center (KDC, Key Distribution Center) or a key transfer center (KTC, Key Transportation Center). Implementation, Figures 1-4 show several basic modes that are common, where k is the communication session key between the first entity A and the second entity B.

In FIG. 1, the first entity A requests the key distribution center to distribute the key used for communication with the second entity B, and the key distribution center generates k to be transmitted to the first entity A and the second entity B, respectively. The key distribution center and the A and the key distribution center and the pre-shared key encryption of B are implemented. In FIG. 2, the first entity A requests the key distribution center to distribute the key used for communication with the second entity B, and is dense. The key distribution center generates k to be passed to the first entity A, and is forwarded to the second entity B through A, and the transfer (transfer) process utilizes the pre-shared key of the key distribution center and the A and the key distribution center and B, respectively. Encryption implementation.

In FIG. 3, the first entity A transmits the communication key k with the second entity B to the key transfer center, and the key transfer center transfers to the second entity B, and the transfer process utilizes the key transfer center respectively. The pre-shared key encryption with A and the key forwarding center and B is implemented; in FIG. 4, the first entity A transmits the communication key k with the second entity B to the key transfer center, the key transfer center Then, it is forwarded to the second entity B through A, and the transfer process is implemented by using the key transfer center and the pre-shared key encryption of the A and the key transfer center and B respectively.

Since a key distribution center or key transfer center participates, each pair of entities can use a new communication key for each communication, but each user needs to save a share with the key distribution center or key transfer center. The secret management key used for a long time, and for the key distribution center and the key transfer center, not only need to store a huge number of secret management keys, but also bear a large security risk, because if there is a problem, it will directly Threatening the security of the entire system, and the above-mentioned key distribution methods do not have the perfect forward secrecy (PFS) of the key.

Embodiments of the present invention provide a key distribution method and an online update method, which reduce system key management complexity and support online update of a trusted third party's public key.

A key distribution method provided by an embodiment of the present invention includes the following steps:

The key distribution center receives a key request message sent by the first entity before the secure communication is performed or when the communication session key needs to be updated, the key request message includes the first temporary public key of the first entity; Receiving, by the distribution center, a key request message sent by the second entity, where the key request message includes a second temporary public key of the second entity;

The key distribution center generates a communication session key for use between the entities, and encrypts the communication session key using the first temporary public key of the first entity, and calculates the signature using the private key of the key distribution center, and passes The key response message transmits the signature and the encrypted communication session key to the first entity; encrypting the communication session key using the second temporary public key of the second entity, and calculating the private key of the key distribution center Signing, and transmitting the signature and the encrypted communication session key to the second entity by using a key response message;

After receiving the key response message, the first entity performs signature verification by using the public key of the locally stored key distribution center; after the verification is passed, the first temporary private key of the first entity is used to decrypt and obtain the communication session key;

After receiving the key response message, the second entity performs signature verification by using the public key of the locally stored key distribution center; after the verification is passed, the communication session is decrypted by using the second temporary private key of the second entity. Key.

A method for updating a public key in an online manner according to an embodiment of the present invention includes the following steps: The key distribution center receives a public key request message sent by an entity, where the public key request message includes a random number generated by the entity;

After receiving the public key request message, the key distribution center returns a public key response message, and the public key response message includes a random number generated by the entity, a new public key of the key distribution center, and an old private key of the key distribution center. Signature

After receiving the public key response message, the entity verifies whether the random number is the same as the random number contained in the public key request message sent by the entity; and uses the locally saved public key to verify whether the signature is correct, and if the verification passes, The new public key updates the locally stored public key.

The embodiment of the invention further provides a key distribution method for updating a public key online, comprising the following steps:

The first entity generates a pair of temporary public-private key pairs, and sends a key request message to the key distribution center, where the message includes the temporary public key of the first entity and the public key of the locally stored key distribution center;

After receiving the key request message sent by the first entity, the key distribution center generates a communication session key between the first entity and the second entity, and encrypts the communication session key by using the temporary public key of the first entity to form a first An ciphertext of an entity; determining whether the public key of the key distribution center carried in the key request message is an old public key or a new public key, and if the old public key is used, the ciphertext and the secret of the first entity are obtained through a key response message The new public key of the key distribution center and the signature are returned to the first entity, wherein the signature is calculated by using the old private key of the key distribution center for other fields in the key response message except the signature; if it is a new public key, Returning, by the key response message, the ciphertext and the signature of the first entity to the first entity, where the signature is calculated by using a new private key of the key distribution center for other fields in the key response message except the signature;

After receiving the key response message, the first entity performs signature verification by using the public key of the locally stored key distribution center. After the verification is passed, if the key response message includes the new public key of the key distribution center, the local storage update is performed. And decrypting the temporary session private key of the first entity to obtain the communication session key; the second entity generates a pair of temporary public and private key pairs, and sends a key request message to the key distribution center, where the message includes the temporary public key of the second entity and The public key of the locally stored key distribution center;

After the key distribution center receives the key request message sent by the second entity, the second entity is used. The public key encrypts the communication session key to form a second ciphertext, and determines whether the public key of the key distribution center carried in the key request message is an old public key or a new public key, and if it is an old public key, The ciphertext of the second entity, the new public key of the key distribution center, and the signature forming key response message are returned to the second entity, wherein the signature is the old private key of the key distribution center, and the key response message is other than the signature. The other field is calculated; if it is a new public key, the ciphertext and the signature of the second entity are returned to the second entity through the key response message, wherein the signature is in the key response message by using the new private key of the key distribution center. Fields other than signatures are calculated;

After receiving the key response message, the second entity performs signature verification by using the public key of the locally stored key distribution center. After the verification is passed, if the key response message includes the new public key of the key distribution center, the local storage update is performed. And decrypting the temporary session private key of the second entity to obtain the communication session key.

A system for implementing key distribution according to an embodiment of the present invention includes:

The first entity is configured to generate a pair of temporary public-private key pairs, and send a key request message to the key distribution center, where the message includes a temporary public key of the first entity, and receives a key response message of the key distribution center; And generating a pair of temporary public-private key pairs, sending a key request message to the key distribution center, the message includes a temporary public key of the second entity, and receiving a key response message of the key distribution center; Responding to the key request of the first entity and the second entity; generating a communication session key for the entity and encrypting the communication session key; calculating the signature by using the private key of the key distribution center, And sending the signature and the encrypted communication session key to the first entity and the second entity by using a key response message;

After receiving the key response message, the first entity performs signature verification by using the public key of the locally stored key distribution center; after the verification is passed, the communication session key is decrypted by using the first temporary private key of the first entity. ;

After receiving the key response message, the second entity performs signature verification by using the public key of the locally stored key distribution center; after the verification is passed, the communication session key is decrypted by using the second temporary private key of the second entity.

The embodiment of the invention further provides a system for implementing online update of a public key, including:

An entity, configured to generate a random number, send a public key request message to the key distribution center, the message includes the generated random number, and receives a public key response message of the key distribution center;

a key distribution center, receiving a public key request message sent by the entity, and returning the public key to the entity In response to the message, the public key response message includes a random number generated by the entity, a new public key of the key distribution center, and a signature made using the old private key of the key distribution center;

The entity verifies that the random number in the public key response message is the same as the random number generated by the entity, and uses the locally saved public key to verify whether the signature is correct. If the verification succeeds, the locally stored public key is updated with the new public key.

The invention is based on the principle of ternary peer-to-peer authentication (TePA), adopts public key cryptography technology, distributes keys for entities requiring communication through the key distribution center KDC, realizes secure distribution and dynamic update of communication keys, and has perfect The forward-secret PFS solves the problem that the traditional key distribution center needs to manage a large number of keys, the user needs to store the long-term secret key, and the communication key does not have forward confidentiality; and the present invention supports the key distribution center KDC. The public key online update function improves security and reliability. DRAWINGS

1 to 4 are schematic diagrams of a key distribution method based on a key distribution center or a key transfer center in the prior art;

FIG. 5 is a diagram of a key distribution method in an embodiment of the present invention; FIG.

FIG. 6 is a diagram of a method for updating a public key online according to an embodiment of the present invention. detailed description

The key distribution center has a pair of public and private key pairs X and Ρχ. The communication entity should obtain the public key Px of the key distribution center before communication and store it locally. When the first entity A and the second entity B need to perform secure communication, the communication session key is obtained through the key distribution protocol.

Referring to FIG. 5, the key distribution method using public key cryptography provided in the embodiment of the present invention is as follows:

1) The first entity A generates a pair of temporary public and private key pairs a and Pa, and sends a key request message to the key distribution center, the key request message containing the temporary public key Pa of the first entity A;

2) After receiving the key request message sent by the first entity A, the key distribution center generates a communication session key k between the first entity A and the second entity B, and the key distribution center uses the first entity A. The temporary public key Pa encrypts the communication session key k, and uses the private key X of the key distribution center to calculate its signature, and returns the signature and the encrypted communication session key to the first entity A through the key response message;

3) After receiving the key response message, the first entity A uses the locally stored key distribution center The public key Px performs signature verification, and after the verification is passed, the communication session key k is decrypted by using the temporary private key a of the first entity A;

4) The second entity B generates a pair of temporary public-private key pairs b and Pb, and sends a key request message to the key distribution center, the message containing the temporary public key Pb of the second entity B;

5) After receiving the key request message sent by the second entity B, the key distribution center encrypts the communication session key k between the first entity A and the second entity B by using the temporary public key Pb of the second entity B. Then, using the private key X of the key distribution center to calculate its signature, the signature and the encrypted communication session key are returned to the second entity B through the key response message;

6) After receiving the key response message, the second entity B performs signature verification by using the public key Px of the locally stored key distribution center. After the verification is passed, the private session b of the temporary second entity B is used to decrypt the communication session. Key k;

7) The first entity A and the second entity B perform secure communication using the communication session key k as a session key.

The first entity A and the B do not need to store the respective temporary public-private key pairs, and may delete them in time, and re-generate the temporary public-private key when the confidential communication is started next time or the communication session key needs to be updated during the confidential communication process. Yes, the key request message is sent to the key distribution center, and the above steps are repeated to obtain a new session key.

The key request message and the key response message carry security parameters, and the encryption parameters, working mode, and working parameters are determined by using the carried security parameter negotiation.

The information of the other party's entity is carried in the key request message sent by the first entity A and the second entity B to the key distribution center, and the first entity and the second entity mutually determine the identity of the other party based on the information of the counterpart entity.

The key distribution method using the public key cryptography technique of the present invention can be extended to the application of the secret communication session key between three or more entities for each communication.

An embodiment of the present invention further provides a system for implementing key distribution, including:

The first entity is configured to generate a pair of temporary public-private key pairs, and send a key request message to the key distribution center, where the message includes a temporary public key of the first entity, and receives a key response message of the key distribution center; And generating a pair of temporary public-private key pairs, sending a key request message to the key distribution center, the message includes a temporary public key of the second entity, and receiving a key response message of the key distribution center; a key distribution center, configured to respond to a key request of the first entity and the second entity; generating a communication session key for the entity and encrypting the communication session key with the temporary public key of the entity; Calculating the signature of the key distribution center by using the private key of the key distribution center, and transmitting the signature and the encrypted communication session key to the first entity and the second entity through the key response message;

The system for implementing key distribution has one or more other entities that communicate with the first entity and/or the second entity.

The other one or more entities are configured to generate a pair of temporary public and private key pairs, and send a key request message to the key distribution center, where each request message includes a respective temporary public key, and receives a key of the key distribution center. Response message

The key distribution center separately encrypts the communication session key by using a temporary public key of each of the other one or more entities; and calculating a signature by using a private key of the key distribution center, and respectively using a key response message The signature and the encrypted communication session key are sent to the other one or more entities;

After receiving the key response message, the other one or more entities perform signature verification using the public key of the locally stored key distribution center; after the verification is passed, the first temporary private key is decrypted to obtain the communication session secret. key.

In the case of security considerations or in order to meet the needs of the communication service, the public and private key pairs of the key distribution center need to be updated periodically or dynamically, and the new public-private key pairs are respectively recorded as x' and Ρχ', where the new public key Ρχ' online notification There are two ways to implement each communication entity:

See Figure 6. The public key of the independent key distribution center is updated online. The steps are as follows:

1) The entity sends a public key request message to the key distribution center; the public key request message contains a random number r generated by the entity;

2) After receiving the public key request message, the key distribution center returns a public key response message; the public key response The message includes a random number r generated by the entity, a new public key Px of the key distribution center, and a signature made by the old private key X of the key distribution center;

3) After receiving the public key response message, the entity verifies whether the random number is the same as the random number r contained in the public key request message sent by the entity; and uses the locally saved public key Px to verify whether the signature is correct; , then update the locally stored public key with the new public key Px.

In a specific application, after the key distribution center first issues a public key update notification to each entity, each entity obtains a new public key through the above steps.

In a specific application, the public key request message further includes a public key of the key distribution center stored locally by the entity. After receiving the public key request message, the key distribution center determines that the public key of the key distribution center carried by the key is the old public key. Px is also the new public key Px. If it is the new public key Px, the message is directly discarded. If it is the old public key Px, the public key response message is returned.

In a specific application, the key distribution center needs to know whether each entity obtains a new public key, and after receiving the public key response message and verifying the pass, the entity sends a public key update confirmation message to the key distribution center.

The present invention also provides a key distribution method for updating a public key online, and adding a public key update function in the above key distribution method, the steps of which are as follows:

1) The first entity A generates a pair of temporary public-private key pairs a and Pa, and sends a key request message to the key distribution center, the message including the temporary public key Pa of the first entity A and the publicly stored key distribution center Key

2) After receiving the key request message sent by the first entity A, the key distribution center generates a communication session key k between the first entity A and the second entity B, and the key distribution center uses the first entity A. The temporary public key Pa encrypts the communication session key k to form the ciphertext cl of the first entity A, and determines whether the public key of the key distribution center carried in the key request message is the old public key Px or the new public key Ρχ ', if it is old The public key Px returns the ciphertext cl, the new public key Px of the key distribution center, and the signature constituting key response message to the first entity A, wherein the signature is the old private key X pair key using the key distribution center In the response message, the field other than the signature is calculated; if it is the new public key Px, the ciphertext cl and the signature-constituting key response message are returned to the first entity A, wherein the signature is a new one using the key distribution center The private key x is calculated for other fields than the signature in the key response message;

3) After receiving the key response message, the first entity A performs signature verification using the public key of the locally stored key distribution center. After the verification is passed, if the key response message includes the new key of the key distribution center Key Px,, then perform local storage update, and then use the temporary private key a of the first entity A to decrypt to obtain the communication session key k;

4) The second entity B generates a pair of temporary public-private key pairs b and Pb, and sends a key request message to the key distribution center, the message including the public key Pb of the temporary second entity B and the publicly stored key distribution center Key

5) After receiving the key request message sent by the second entity B, the key distribution center encrypts the communication session key k between the first entity A and the second entity B by using the temporary public key Pb of the second entity B. The ciphertext c2 of the second entity B is formed to determine whether the public key of the key distribution center carried in the key request message is the old public key Px or the new public key Px, and if it is the old public key Px, the ciphertext c2 is obtained. The new public key Px of the key distribution center and the signature-constituting key response message are returned to the second entity B, wherein the signature is the old private key X of the key distribution center, and the other fields other than the signature in the key response message If the new public key Px is obtained, the ciphertext c2 and the signature constituting key response message are returned to the second entity B, where the signature is a new private key x using the key distribution center, and the key response message is used. Fields other than signatures are calculated;

6) After receiving the key response message, the second entity B performs signature verification by using the public key of the locally stored key distribution center. After the verification is passed, if the key response message includes the new public key Px of the key distribution center, Then performing local storage update, and then decrypting the temporary session private key b of the second entity B to obtain the communication session key k;

The key request message and the key response message may carry security parameters, and use the carried security parameters to negotiate to determine an encryption algorithm, a working mode, and a working parameter.

The key request message sent by the first entity A and the second entity B to the key distribution center may carry the information of the counterpart entity.

The key distribution method for updating the public key of the present invention can be extended to three and three times for each communication. The application of the secret communication session key between more than one entity.

The key distribution center receives the public key request message sent by the entity, and returns a public key response message to the entity, where the public key response message includes a random number generated by the entity, a new public key of the key distribution center, and a key distribution center. The signature of the old private key;

Before the entity sends a public key request message to the key distribution center, the key distribution center first issues a public key update notification to each entity.

The public key request message further includes a public key of a key distribution center stored locally by the entity; the key distribution center further includes:

a judging module, configured to determine whether the public key of the key distribution center carried in the public key request message is an old public key or a new public key;

a processing module, if the determining module determines that the public key of the key distribution center is a new public key, directly discarding the message, and if it is determined that the public key of the key distribution center is an old public key, The public key response message informs the entity.

It will be apparent to those skilled in the art that the various modules (functions) or steps of the present invention described above can be implemented by a general-purpose computing device that can be centralized on a single computing device or distributed across multiple computing devices. Optionally, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device, or they may be separately fabricated into individual integrated circuit modules, or Implementing multiple modules (functions) or steps in them into a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software.

The above description is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications, equivalents, improvements, etc. made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

Claim

A key distribution method, comprising the steps of:

After receiving the key response message, the second entity performs signature verification by using the public key of the locally stored key distribution center; after the verification is passed, the communication session key is obtained by decrypting the second temporary private key of the second entity.

2. The key distribution method according to claim 1, further comprising: each time a key request message is sent to the key distribution center, the first entity provides a pair of new temporary public-private key pairs: The first temporary public key and the first temporary private key, the second entity provides a pair of new temporary public and private key pairs: a second temporary public key and a second temporary private key.

The key distribution method according to claim 1, wherein the key request message and the key response message carry security parameters, and the method further includes:

The encryption algorithm, working mode, and working parameters are determined by using the carried security parameters.

The key distribution method according to claim 1, wherein the key request message sent by the first entity and the second entity to the key distribution center carries information of the counterpart entity, based on the information of the counterpart entity. The first entity and the second entity determine each other's identity.

5. The key distribution method according to claim 1, wherein the system has a The first entity and/or the second entity interact with one or more other entities, the method further comprising:

Separating the communication session key with the temporary public key of the other one or more entities; calculating the signature by using the private key of the key distribution center, and respectively authenticating the signature and the encrypted communication session by using a key response message The key is sent to the other one or more entities.

6. A method for updating a public key online, comprising the steps of:

The key distribution center receives a public key request message sent by the entity, and the public key request message includes a random number generated by the entity;

The method for updating a public key online according to claim 6, wherein before the entity sends the public key request message to the key distribution center, the key distribution center first issues a public key update notification to each entity.

The public key online update method according to claim 6, wherein the public key request message further includes a public key of a key distribution center stored locally by the entity;

After receiving the public key request message, the key distribution center determines whether the public key of the key distribution center carried by the key distribution center is the old public key or the new public key. If it is a new public key, the message is directly discarded, if it is the old public key. And notifying the entity by the public key response message.

The public key online update method according to claim 6, further comprising: after the entity updates the locally stored public key with the new public key, and sends a public key update confirmation message to the key distribution center.

A key distribution method for updating a public key online, comprising the steps of: the first entity generating a pair of temporary public-private key pairs, and transmitting a key request message to the key distribution center, the message including the first The temporary public key of the entity and the public key of the locally stored key distribution center;

After the key distribution center receives the key request message sent by the first entity, the first entity and the first a communication session key between the two entities, using the temporary public key of the first entity to encrypt the communication session key to form a ciphertext of the first entity; determining that the public key of the key distribution center carried by the key request message is the old public key Or the new public key, if it is the old public key, the ciphertext of the first entity, the new public key of the key distribution center, and the signature are returned to the first entity through the key response message, wherein the signature is the key distribution center The old private key is calculated in the key response message except for the signature; if it is a new public key, the ciphertext and the signature of the first entity are returned to the first entity through the key response message, wherein the signature is utilized The new private key of the key distribution center is calculated in the key response message except for the signature;

After receiving the key request message sent by the second entity, the key distribution center encrypts the communication session key by using the temporary public key of the second entity to form a second ciphertext, and determines the key carried in the key request message. Whether the public key of the distribution center is the old public key or the new public key, and if it is the old public key, the ciphertext of the second entity, the new public key of the key distribution center, and the signature forming key response message are returned to the second entity. The signature is calculated by using the old private key of the key distribution center for other fields than the signature in the key response message; if it is a new public key, the ciphertext and signature of the second entity are returned by the key response message. Giving the second entity, wherein the signature is calculated by using a new private key of the key distribution center for other fields in the key response message other than the signature;

The key distribution method according to claim 10, wherein the key request message and the key response message carry security parameters, and the method further includes:

The key distribution method according to claim 10, wherein the key request message sent by the first entity and the second entity to the key distribution center carries information of the counterpart entity, The first entity and the second entity determine the identity of the other party with respect to the information of the counterpart entity.

The key distribution method according to claim 10, wherein the system has another one or more entities that communicate with the first entity and/or the second entity, and the method further includes:

14. A system for implementing key distribution, comprising:

15. The system for implementing key distribution according to claim 14, characterized by having one or more other entities that communicate with the first entity and/or the second entity.

The key distribution center encrypts the communication session key separately using respective temporary public keys of the other one or more entities; and calculates a signature by using a private key of the key distribution center, and passes the secret The key response message respectively sends the signature and the encrypted communication session key to the other one or more entities;

16. A system for implementing an online update of a public key, comprising:

17. The system for implementing an online update public key according to claim 16, wherein the key distribution center first issues a public key update notification to each entity before the entity sends the public key request message to the key distribution center.

The system for implementing online update of a public key according to claim 16, wherein the public key request message further includes a public key of a key distribution center stored locally by the entity;

The key distribution center also includes: