CN1592195A - Method for protecting information integrity - Google Patents

Abstract

The invention discloses a method for protecting the integrity of information applied in the wireless field. The method comprises: the user obtains and stores the public key of the multicast/broadcast server; the multicast/broadcast server sends the information with integrity protection to The user, the user uses the public key to check whether the integrity protection information in the received information is valid, and if so, the user determines that the information has integrity; otherwise, the user determines that the information does not have integrity. According to the method proposed by the present invention, the security protection of the information sent by the multicast/broadcast server is carried out, so that the user can check the received information, so as to determine whether the received information has integrity, and determine the message sending the information Whether the source is reliable can effectively prevent the information in the multicast/broadcast service from being maliciously tampered with or forged by others. In addition, the present invention prevents information from being reused by others by adding a time stamp to the information sent by the multicast/broadcast server.

Description

A Method of Protecting Information Integrity

technical field

The invention relates to information security technology in multicast/broadcast services, in particular to a method for protecting information integrity.

Background technique

In a wireless communication network, multicast/broadcast services refer to point-to-multipoint unidirectional bearer services, where data information is sent from one original entity to multiple receiving entities, and data information is sent to multiple user equipments by a multicast/broadcast server. The data information transmitted from point to multipoint can be multicast/broadcast service information, or signaling information used to control multicast/broadcast service. Compared with the service information, the signaling information is much less, but the signaling information is much more important than the service information, because the signaling information controls the multicast/broadcast service. A multicast/broadcast server refers to a functional entity that can provide multicast/broadcast business services and has key generation and management functions. It can be a newly added functional entity in the wireless communication network, or it can be a A functional entity or a combination of multiple functional entities.

At present, the service information in the multicast/broadcast service has been encrypted and sent. For example, the multicast/broadcast server uses the group shared key shared by the user in the group to encrypt the service information and then sends it to the group. Users, users in the group use their own group shared key to decrypt the received service information, and then obtain multicast/broadcast service information. However, the signaling information in the multicast/broadcast service is usually broadcast directly without encryption, because some signaling information is not suitable for encryption, such as the broadcast information used to control which group shared key is currently used by the users in the group. If the signaling information is encrypted, those users who are not in the multicast/broadcast service group but have just joined the multicast/broadcast service group and have not used the correct group shared key cannot Receive the broadcasted signaling information; in addition, the signaling information generally does not carry information content that needs to be kept secret, so there is no need for encryption at all. However, since the signaling information is used to control multicast/broadcast services, it needs to be highly Ensure the integrity of signaling information.

If the signaling information broadcast by the multicast/broadcast server is modified by an attacker during transmission, the multicast/broadcast service system may not work properly. For example, the multicast/broadcast server notifies the users in the group to use the group shared key numbered 5 to decrypt the subsequent received service information, because the signaling information only carries the number of the group shared key and does not carry the corresponding The group shared key, so the signaling information can be sent in plain text; because the signaling information is not protected by the corresponding integrity, it may be attacked, and the attacker modifies the signaling information by 5 during sending It is 3. After receiving the signaling information, the users in the group do not know that the signaling information has been modified, so they use the group shared key numbered 3 to decrypt the received service information according to the instructions in the signaling information. This will cause all users in the group to be unable to normally receive subsequent multicast/broadcast service information. Attackers can also use their own information to replace the signaling information broadcast by the real multicast/broadcast server, or directly impersonate the multicast/broadcast server to broadcast and send signaling information, which will cause users in the group to fail to receive multicast/broadcast normally Business information, serious consequences of multicast/broadcast business systems not operating normally.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for protecting information integrity, which ensures that users in a group normally receive information of multicast/broadcast services, and at the same time ensures the normal operation of the multicast/broadcast service system.

In order to achieve the above object, the present invention provides a method for protecting information integrity, which method includes the following steps:

A. The user obtains and stores the public key of the multicast/broadcast server;

B. The multicast/broadcast server sends the integrity-protected information to the user;

C. The user uses the public key to check whether the integrity protection information in the received information is valid, and if yes, it is determined that the information has integrity; otherwise, it is determined that the information does not have integrity.

The step A includes: the multicast/broadcast server sends the multicast/broadcast server public key to the user, and the user stores the received public key.

The step A further includes: the multicast/broadcast server uses the integrity key and the encryption key generated by the user to join the multicast/broadcast service authentication process to perform integrity protection and encryption on the multicast/broadcast server public key, and then send it to The user, the user decrypts the received public key and stores it after performing an integrity check.

Described step A further comprises the following steps: A1, the multicast/broadcast server provides the public key of the multicast/broadcast server to the certificate authority, and after the certificate authority generates the public key certificate that contains the public key of the multicast/broadcast server, it uses the private key of the certificate authority to key to encrypt the public key certificate of the multicast/broadcast server, and become the public key certificate issued by the certificate authority for the multicast/broadcast server; A2. The multicast/broadcast server sends the public key certificate issued by the certificate authority to the user, and the user Storing the public key certificate containing the public key of the multicast/broadcast server, the step C includes: the user uses the public key in the public key certificate of the multicast/broadcast server to verify whether the digital signature in the received information is valid.

The step A2 further includes: the user requests the certificate authority to provide the public key corresponding to the private key of the certificate authority, the user stores the received public key of the certificate authority, and uses the public key of the certificate authority to verify the validity of the public key certificate Validity, if valid, the user stores the public key certificate; otherwise, the user discards the public key certificate.

Preferably, the step B includes: the multicast/broadcast server uses the multicast/broadcast server private key corresponding to the public key in step A to digitally sign the information and then sends it to the user; the step C includes: The user uses the public key mentioned in step A to verify whether the digital signature in the received information is valid.

The step B further includes the following steps: B1. After the multicast/broadcast server digests the information content using a digest algorithm, it encrypts the digest with the private key of the multicast/broadcast server, and then combines the information content with the encrypted The final summary is sent to the user together; B2. After the user receives the information, the user uses the summary algorithm to perform summary processing on the information content to obtain a summary; B3. The user uses the multicast/broadcast corresponding to the multicast/broadcast server private key The server public key decrypts the digest in the received information content, and then judges whether the decrypted digest is consistent with the digest calculated by the user.

Before the step B, it further includes: the multicast/broadcast server adds a time stamp identifying the sending time of the information to the information content; after the step C determines that the information has integrity, it further includes: the user judges whether the time stamp of the information is late If it is based on the timestamp stored by itself, update the timestamp stored by itself to the timestamp of the received message; otherwise, consider the message to be illegally reused and discard the message.

After determining that the information is not complete in step C, it further includes D: after a time delay, the user feeds back abnormal information to the multicast/broadcast server.

After the step D, it further includes E: the multicast/broadcast server notifies all users to stop feeding abnormal information.

Different users have different said time delays.

If the information is multicast/broadcast service information, the step B further includes: the multicast/broadcast server encrypts the multicast/broadcast service information.

According to the method proposed by the present invention, the security protection of the information sent by the multicast/broadcast server is carried out, so that the user can check the received information, thereby determining whether the received information has integrity, and determining the message sending the information Whether the source is reliable can effectively prevent the information in the multicast/broadcast service from being maliciously tampered with or forged by others. In addition, the present invention prevents information from being reused by others by adding a time stamp to the information sent by the multicast/broadcast server. The present invention also provides multiple implementations, which can be flexibly selected according to actual applications; when digital signatures are used to ensure information integrity and security, the multicast/broadcast server encrypts the public key and sends it to the user, which can prevent attackers from The public key is tampered with or replaced during transmission.

Description of drawings

Fig. 1 is the flow chart that realizes signaling information integrity and security in the present invention;

Fig. 2 is a schematic diagram of another embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

In the present invention, the multicast/broadcast server uses the private key to protect the integrity of the sent information content, and the users in the group use the public key corresponding to the private key to check whether the integrity information in the received information is valid. , it proves that the content of the information has not been modified during sending and the source of the sending information is reliable, so the information has integrity, and the corresponding operation is performed according to the instructions of the information, otherwise, the information does not have integrity, and the received information is not processed , so as to ensure the integrity and reliability of the information received by users.

Fig. 1 is the flow chart that realizes signaling information integrity and security in the present invention, as shown in Fig. 1, the processing flow that realizes signaling information integrity and security comprises the following steps:

Step 101 to Step 103: the multicast/broadcast server sends its own public key to the users in the group. The multicast/broadcast server uses the private key corresponding to the public key to digitally sign the content of the signaling information, and then broadcasts it to the users in the group; the users in the group use the public key to verify whether the digital signature in the signaling information is valid, if Yes, it proves that the content of the signaling information has not been modified during transmission and the source of the signaling information is reliable, so the signaling information has integrity and security, and the corresponding operations are performed according to the instructions of the signaling information, otherwise, no The received signaling information is processed, or step 104 is executed after a certain time delay.

In order to increase the security of the public key and prevent the public key from being maliciously tampered with by others during transmission, the multicast/broadcast server can protect the integrity and encryption of the public key and send it to the users in the group. The public key is decrypted and its integrity verified before being stored.

Step 104~Step 105: After a certain time delay, users in the group feed back abnormal information to the multicast/broadcast server, and the multicast/broadcast server can notify All users in the group stop feeding back abnormal information, so as to avoid all users in the group feeding back the same abnormal information, resulting in a waste of multicast/broadcast service system resources. The corresponding strategy can be that the number of users in the group that feedback abnormality exceeds a certain number The stop feedback notification is only sent, because there may be a user error in a certain group when doing the integrity check, rather than the real signaling information being modified, so there will not be a large number of users in the group feedback, stop feedback notification It is not necessary, if the user in the group has an abnormality, it will enter into other processing flow, which is not within the description scope of the present invention. In order to prevent a large number of users in a group from feeding back the same abnormal information to the multicast/broadcast server at the same time, and more effectively avoid the waste of multicast/broadcast service system resources, the time delay of users in different groups can be different In this way, as long as the multicast/broadcast server receives abnormal information fed back by a relatively small number of users in the group, it can notify all users in the group to stop feeding abnormal information.

In order to effectively prevent the digitally signed signaling information from being reused by others, a time stamp can be further added to the signaling information broadcast by the multicast/broadcast server, and the multicast/broadcast server digitally signs the content of the signaling information and the time stamp After verifying that the digital signature is valid, the users in the group continue to judge whether the currently received signaling information is the latest through the timestamp, that is, judge whether the timestamp is fresh, and if so, perform corresponding operations according to the instructions of the signaling information ; Otherwise, do not process the received signaling information.

The users in the group store the time variable of the signaling information sent by the multicast/broadcast server. The initial value of the time variable is the time stamp when the multicast/broadcast server sends the signaling information for the first time. Every time a user in the group receives a For signaling information with integrity and security, the time variable stored in itself is updated to be the timestamp of the currently received signaling information. The process of judging whether the timestamp is fresh is as follows: After receiving the signaling information, the users in the group compare the timestamp in the signaling information with the timestamp stored in themselves. If the timestamp of the currently received signaling information is older than If the timestamp stored by itself is late, confirm that the signaling information is valid new signaling information, perform corresponding operations according to the instructions of the signaling information and update the timestamp stored by itself to the timestamp of the current received signaling information; if the current If the time stamp of the received signaling information is earlier or the same as the time stamp stored in itself, the signaling information is confirmed to be invalid signaling information, and the received signaling information is not processed. If there are multiple multicast/broadcast servers, the users in the group store time variables corresponding to each multicast/broadcast server for different multicast/broadcast servers.

FIG. 2 is a schematic diagram of another embodiment of the present invention. As shown in FIG. 2, the processing flow for realizing the integrity and security of signaling information in this embodiment includes the following steps:

Steps 201 to 202: The user requests to join the multicast/broadcast service, and the multicast/broadcast server verifies the user's identity. While verifying the user's identity, the multicast/broadcast server and the user simultaneously generate and store an encryption key and an encryption key for complete Integrity key with permanent protection; if the user passes the identity verification, the user will be confirmed as a user in the group by the multicast/broadcast server, and the multicast/broadcast server will send the integrity key protected and encrypted key to the user in the group Encrypted public key; after users in the group receive the encrypted public key, they use their own stored encryption key and integrity key to decrypt and perform integrity verification, and store the public key after the decryption succeeds and the integrity verification passes. key. If the user is not authenticated, the multicast/broadcast server refuses to provide the multicast/broadcast service.

Steps 203 to 204: The multicast/broadcast server uses the private key corresponding to the public key to digitally sign the content of the signaling information and the time stamp, and then broadcasts it to the users in the group; the users in the group use the public key to verify Whether the digital signature in the signaling information is valid, if so, it proves that the content and time stamp of the signaling information have not been modified during the transmission, and the source of the signaling information is reliable, so the signaling information has integrity and security , then execute step 205, otherwise, do not process the received signaling information, or execute step 206 after a certain time delay.

The content of the signaling information and the timestamp can be digitally signed through the digest algorithm. The digest algorithm that can be used includes the MD5 algorithm, the SHA-1 algorithm, etc., and the digest algorithm is used to perform digest processing on the content of the signaling information and the timestamp together, and then The digest is encrypted with a private key that only the multicast/broadcast server itself knows, and finally the encrypted digest is attached to the content of the signaling information and the time stamp to become a digital signature of the content of the signaling information and the time stamp, and broadcast to users in the group.

After the users in the group receive the signaling information, they use the public key corresponding to the private key to verify whether the digital signature in the signaling information is valid. After the digest is processed, the digest is obtained, and then the digital signature is decrypted using the public key, and the digest obtained by itself is compared with the digest obtained by decryption. If they are consistent, it proves that the content of the signaling information and the time stamp have not been modified during transmission, and The message source that sends the signaling information is reliable and has integrity and security; otherwise, the signaling information does not have integrity and security.

The abstract algorithm can calculate a fixed-length output for an input of an unfixed length, and it is impossible to deduce what the input is based on the output. Different inputs correspond to different outputs, and even if a small change is made to the input, a different result will be obtained. output, even resulting in very variable output. Since the private key is only known by the multicast/broadcast server itself, it is impossible for others to fake the multicast/broadcast server to broadcast signaling information to users in the group through digital signatures; Modify the signaling information content and time stamp during the sending process without being discovered by users in the group.

Step 205: The users in the group check whether the time stamp of the signaling information is fresh, if so, update the time variable stored by themselves to the time stamp of the currently received signaling information, and perform corresponding operations according to the instructions of the signaling information; Otherwise, the received signaling information is not processed, or step 206 is executed after a certain time delay.

Step 206-Step 207: The time delays of users in a group are different. After a certain time delay of a user in a group, the abnormal information is fed back to the multicast/broadcast server, and the multicast/broadcast server receives the group After receiving abnormal information fed back by internal users, notify all users in the group to stop feeding abnormal information, so as to avoid the waste of multicast/broadcast service system resources caused by feedback of the same abnormal information by users in all groups.

In addition, the wireless communication network can be combined with a public key infrastructure (PKI). The PKI system is composed of several devices, providing a trusted application environment, so that the above public key/private key encryption and decryption method can be applied to various business services. Included in the PKI system is a Certificate Authority (CA), which is an authority that is fully trusted by all users or entities.

The multicast/broadcast server securely provides its public key to the certificate authority, and the certificate authority makes a public key certificate. The public key certificate includes the public key and private information of the multicast/broadcast server. The private information includes information such as name and address. The certificate authority makes the public key and private information of the multicast/broadcast server into a public key certificate, and uses its own private key to digitally sign the public key certificate to become a formal public key certificate. The digital signature of the certificate authority proves the public key certificate issued by it. Since the certificate authority is an authority, all users or entities can absolutely trust the public key certificates issued by it. The private key of the certificate authority needs to be kept extremely confidential; the public key corresponding to the private key of the certificate authority is public. After the users in the group securely obtain the public key of the certificate authority, they can use the public key of the certificate authority to verify multiple The validity of the public key certificate of the broadcast broadcast server.

For example, the users in the group store the public key of the certificate authority obtained securely from the certificate authority. The multicast/broadcast server sends its own public key certificate to the users in the group. This sending process does not need to be kept secret. After receiving the public key certificate of the multicast/broadcast server, the users in the group use the public key of the certificate authority Verify the obtained public key certificate to check whether it is issued by the certificate authority. If it is, it is considered to be a legal public key certificate of the multicast/broadcast server, and the user stores this public key certificate. After receiving the signaling information digitally signed by the multicast/broadcast server, the user uses the public key in the public key certificate to verify the digital signature in the signaling information. If the verification is successful, it proves that the signaling information has not been modified during transmission. And the source of the signaling information is reliable, so the signaling information has integrity and security; otherwise, the received signaling information is not processed.

In practical applications, when the wireless communication network is combined with the public key infrastructure (PKI), time stamps can also be added to prevent the signaling information from being reused by others; when users in the group find that the signaling information is invalid, they can send The multicast/broadcast server returns abnormal information.

In addition, when the capabilities and wireless bandwidth of the terminal equipment are sufficient, the above method can be applied to service information in multicast/broadcast services.

In a word, the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (12)

1, a kind of guard method of information integrity is characterized in that the method includes the steps of:

A, user obtain and store the PKI of multicast;

The information that B, multicast will have been carried out integrity protection sends to the user;

C, user use described PKI check to receive whether the integrity protection information in the information is effective, if, judge that described information has integrality, otherwise, judge that described information does not have integrality.

2, method according to claim 1 is characterized in that, described steps A comprises: multicast sends the multicast PKI to the user, the described PKI that user storage is received.

3, method according to claim 2; it is characterized in that; described steps A further comprises: Integrity Key and encryption key that multicast uses the user to add the generation of multicast/broadcast business verification process carry out integrity protection and encryption to the multicast PKI; send to the user then, the described PKI that user's deciphering is received also carries out storing behind the completeness check.

4, method according to claim 1 is characterized in that,

Described steps A further may further comprise the steps:

A1, multicast provide the multicast PKI to certificate agency, after certificate agency generates and comprises the public key certificate of multicast PKI, use the public key certificate of the encrypted private key multicast of certificate agency, becoming certificate agency is the public key certificate that multicast is issued;

A2, multicast send described certificate agency to the user and are its public key certificate of issuing, and user storage comprises the public key certificate of multicast PKI;

Described step C comprises: the user uses the PKI check in the multicast public key certificate to receive whether the digital signature in the information is effective.

5, method according to claim 4, it is characterized in that, described steps A 2 further comprises: the user asks certificate agency to provide and the corresponding PKI of certificate agency private key to it, the described certificate agency PKI that user storage is received, and use the certificate agency PKI to check the validity of described public key certificate, if effectively, the described public key certificate of user storage then; Otherwise the user abandons described public key certificate.

6, method according to claim 1 is characterized in that,

Described step B comprises: multicast is used with the corresponding multicast private key of PKI described in the steps A information is carried out sending to the user after the digital signature;

Described step C comprises: the user uses the check of PKI described in the steps A to receive whether the digital signature in the information is effective.

7, method according to claim 6 is characterized in that, described step B further may further comprise the steps:

B1, multicast use digest algorithm to the information content make a summary handle after, use described multicast private key that described summary is encrypted, then with the information content with encrypt after summary together send to the user;

After B2, user receive information, use described digest algorithm that the information content is made a summary and obtain summary after handling;

B3, user use the summary that dock in the breath content of collecting mail with the corresponding multicast PKI of multicast private key to be decrypted, and whether with summary that user calculate consistent in judgement if deciphering the summary that obtains then.

8, method according to claim 1 is characterized in that,

Further comprise before the described step B: the timestamp of multicast additional identification information transmitting time in the information content;

Judge described in the step C that described information further comprises after having integrality: whether the timestamp of user judgment information is later than the timestamp that self stores, if be the timestamp of receiving information with the update of time stamp of self storing; Otherwise, think that this message is illegally reusable, abandons this message.

9, method according to claim 1 is characterized in that, judge described in the step C that described information further comprises D after not having integrality: user's elapsed time postpones the back to multicast feedback abnormal information.

10, method according to claim 9 is characterized in that, further comprise E after the described step D: multicast notifies all users to stop to feed back abnormal information.

11, method according to claim 9 is characterized in that, different user has different described time delays.

12, method according to claim 1 is characterized in that, if described information is multicast/broadcast business information, then described step B further comprises: multicast is encrypted described multicast/broadcast business information.