CN1780413A - A key control method for multicast broadcast service - Google Patents

Abstract

The method includes following steps: setting public key for mobile station and its relevant private key; with the public key the multicast service delivery server encrypts the cipher key for multicast service, and sends it to mobile station; with the private key, the mobile station receives the cipher key of multicast service; the private key is stored in a module set for preventing illegally decoding the cipher, and is used to decrypt the received key message of multicast service; to secure the safely acquirement for public key, the following method can be adopted: the user id and its corresponding public key are registered in security center, or a digital certificate of public key is issued by mobile station.

Description

A key control method for multicast broadcast service

technical field

The invention relates to a multicast broadcast service, in particular to a key control method for a multicast broadcast service.

Background technique

Multicast and broadcast are a technology to transmit data from one data source to multiple targets. In traditional mobile networks, Cell Broadcast Service (CBS: Cell Broadcast Service) allows low bit rate data to be sent to all users through the cell shared broadcast channel. , belonging to the message business. Now, people's demand for mobile communication is no longer satisfied with telephone and messaging services. With the rapid development of the Internet, a large number of multimedia services have emerged, some of which require multiple users to receive the same data at the same time, such as video on demand, TV, etc. Broadcasting, video conferencing, online education, interactive games, etc. Compared with general data, these mobile multimedia services have the characteristics of large data volume, long duration, and delay sensitivity. The current IP multicast technology is only applicable to wired IP networks, not mobile networks, because mobile networks have specific network structures, functional entities and wireless interfaces, which are different from wired IP networks.

In order to effectively utilize mobile network resources, on the one hand, the global standardization organization 3GPP of the Wideband Code Division Multiple Access System (WCDMA: Wide-band Code Division Multiple Addressing)/Global System for Mobile Communications (GSM: Global System for Mobile communications) proposed the multimedia Multicast and broadcast service (MBMS: Multimedia Broadcast/Multicast Service); on the other hand, the latest protocol IEEE802.16e/D5 of IEEE802.16 also introduces multicast broadcast service (MBS: Multicast and Broadcast Service), these services In a mobile network, a data source sends data to multiple users. In a mobile network, a point-to-multipoint service in which one data source sends data to multiple users realizes network resource sharing and improves network resource utilization, especially air interface resource utilization. The newly provided MBMS or MBS can not only realize plain text low-rate message multicast and broadcast, but also realize multicast and broadcast of high-speed multimedia services, which undoubtedly conforms to the future development trend of mobile data.

The network structure of the MBS service is shown in Figure 1. In order to support the MBS service, a new mobile network functional entity—the multicast broadcast service distribution server (MBS server) is added. On the one hand, it is the entrance of the content provider, on the other hand , it plans the transmission of multicast broadcast data of subordinate base stations (BS: Base Station), and distributes multicast broadcast data to subordinate BSs. In addition, functional entities such as MSS and BS are enhanced to add functions related to MBS services .

The MBS service operation mainly includes the following parts: MBS service list information acquisition, MBS service authentication and encryption key acquisition, and MBS service normal reception.

As shown in Figure 2, the acquisition of MBS service list information mainly includes steps 1 to 3:

1. The mobile station (MSS: Mobile Subscribe Station) decides to query the MBS service content list to find the relevant content server;

2. MSS sends a [HTTP]Request to one or more MBS servers (MBS server);

3. The MBS server (MBS server) sends a [HTTP] Response, which includes the MBS content list, multicast IP address/port number, etc.;

As shown in Figure 3, MBS service authentication and encryption key acquisition mainly include steps 4-8:

4. After obtaining the content list information of the MBS service, the MSS sends a DSA-REQ message to the BS, which includes the multicast IP address/port number of the selected MBS service;

5. The BS sends the DSX-RVD message, and at the same time performs the authentication process for receiving the MBS service content;

6. After a successful authentication and authorization process, the BS sends a DSA-RSP message, which includes MBS downlink service parameters (such as MBS SA-ID, etc.);

7. The MSS sends a PKM-REQ message to the BS to obtain the MBS key, and uses the key to decrypt the received MBS service data;

8. The BS sends a PKM-RSP message to the MSS, including the MBS service key;

After obtaining the MBS downlink service parameters and the MBS key, the MSS uses the obtained information to receive the relevant MAC PDU and enter the normal MBS service receiving state. The normal reception of the MBS service mainly refers to the process of receiving the MBS service content by using the received MBS downlink service parameters. In the current standard draft, the MBS downlink service parameters mainly include MBS zone identifier and Multicast CID.

Public key cryptography, also known as asymmetric cryptography, means that the encryption key and the decryption key are different. The key that can be disclosed is called the public key, and the key that needs to be kept secret is called the private key. It is difficult to derive the private key from the public key. Data encrypted with the public key can be decrypted with the private key, and vice versa, data encrypted with the private key can also be decrypted with the public key. Using public key cryptography, digital signature services can be provided. Digital signature means that the sender encrypts the information with its own private key, and anyone who has the public key corresponding to the private key can decrypt it, because the private key is only owned by the sender and kept secret, and other entities cannot Forge the sender's signature, so it can be regarded as the sender's signature on the information.

In 1978, Kohnfelder introduced the concept of public key certificate in his bachelor's thesis, that is, the public key is passed to a public key user through the certificate. Public key certificates are generally issued by authoritative organizations (such as CA: Certification Authority), and digital signature technology is used to bind the entity's name and other personal identity information with the public key. Currently, there are many different types of commonly used certificates, such as X.509 certificates.

The tamper-resistant cryptographic module is a common technology used in key management, and is generally used in smart card services. The tamper-proof cryptographic module encapsulates important information such as keys in a module through a special manufacturing process. The key information cannot be read from the module by reading instructions, and at the same time, the internal storage cannot be obtained by disassembling the module. information, if you try to disassemble the module, the module will automatically clear the key information stored in the module.

The MBS service is sent on the wireless broadcast channel, and each MSS can receive the data on the broadcast channel, but because the data is encrypted, only the MSS that has registered for a certain MBS service can decrypt the data of the MBS service And receive this MBS service.

Since the MBS service is sent by broadcast in a certain MBS zone (Zone), all MSSs in the MBS Zone that have registered for this MBS service are required to receive the MBS service seamlessly, so the same MBS service data is stored in the same MBS The same key is used for encryption within the zone. In order to enable the MSS registered for a certain MBS service to correctly receive the broadcast data of this service, when the MSS requests the MBS server for a certain MBS service it has registered, the MBS server distributes the MBS service to the authenticated MSS through the key exchange process. The encryption key of the MBS service.

Since the data of the same MBS service is encrypted by the same encryption key and then broadcast on the wireless channel, there is a problem of how to ensure the security of the encryption key transmission process and prevent users who have registered for a certain MBS service from inadvertently The obtained MBS service key will be intentionally leaked or anonymously distributed to other unregistered users. Regarding the above issues, MBS service key management does not provide any guarantee mechanism.

Contents of the invention

This method provides a control method for safely issuing a service key for the multicast broadcast service to ensure the security of the service key. The method for controlling the multicast broadcast service key is implemented through the following steps:

A: Set the public key and its corresponding private key for the mobile station;

B: The multicast broadcast service distribution server encrypts the multicast broadcast service key with the public key and sends it to the mobile station;

C: The mobile station uses the private key to decrypt the received multicast broadcast service key.

The mobile station is provided with an anti-tampering cryptographic module to store the private key; the anti-tampering cryptographic module uses the private key to decrypt and save the multicast broadcast service key received by the mobile station, and uses the multicast broadcast service key to The key decrypts the multicast broadcast service data received by the mobile station.

The public key and the private key are set by an independent security center, and the security center saves the private key of the mobile station in its tamper-proof cryptographic module.

A further step is included between steps A and B: A1: The security center establishes a public key database to register the identification information of the mobile station and its corresponding public key.

The mobile station sends its identification information to the multicast broadcast service distribution server;

The multicast broadcast service distribution server looks up the corresponding public key from the security center through the security channel according to the identification information of the mobile station.

The security center issues a digital certificate for the mobile station, and the digital certificate includes identification information and a public key of the mobile station.

The mobile station sends the digital certificate to the multicast broadcast service distribution server;

The multicast broadcast service distribution server verifies the digital certificate and extracts the identification information and public key of the mobile station.

The control method further includes step D: the mobile station receives the multicast broadcast service data from the multicast broadcast service distribution server, and inputs the multicast broadcast service data into the tamper-resistant password module for decryption.

Using the multicast broadcast service key control method of the present invention can effectively prevent the service key from being stolen during the distribution process, and prevent registered users from intentionally divulging or anonymously distributing the service key to unregistered users after obtaining the service key.

Description of drawings

FIG. 1 is a schematic diagram of a network structure of an MBS service;

Fig. 2 is the flow chart of information interaction for the mobile station to obtain the MBS service list;

Fig. 3 is a flow chart of information interaction for the mobile station to obtain downlink parameters and encryption keys of the MBS service.

Fig. 4 is a flow chart of Embodiment 1.

Detailed ways

In order to receive MBS service data correctly, users who have registered for a certain MBS service must hold MBS service keys, and these keys must be obtained from the MBS server through authentication and key exchange. In order to prevent the service key from being stolen during the exchange process, an independent security center generates a pair of public key and private key for each mobile station using the public key cryptography system. After the MBS server uses the public key to encrypt the MBS service key, then Send it to the mobile station, and the mobile station uses the private key to decrypt it to obtain the MBS service key after receiving it.

Further, the combination of the public key cryptosystem and the anti-tampering cryptographic module stores the user's private key and service key in the anti-tampering cryptographic module, so that the registered user who obtains the encryption key of the MBS service still has no way to contact and This service key is distributed so that registered users cannot reveal or distribute the service's own service key. This scheme requires each user's MSS device to have an anti-tamper password module, which stores the private key in its public key pair, and also integrates data encryption and decryption (including public key Algorithm and Symmetric Key Algorithm) module specifically implements encryption and decryption operations. During authentication and key exchange between the MSS and the MBS server, the MBS server obtains the public key that matches the private key stored in the tamper-resistant password module of the MSS device through a secure way, and the MBS server uses the encryption key of the MBS service with The public key is encrypted and sent to the MSS. The MSS must input the received message into the anti-tampering password module for decryption to obtain the MBS service key. The MBS multicast broadcast service data received by the MSS must also be sent to the anti-tampering password module for decryption. In this way, the user is prevented from directly accessing the MBS service key, effectively preventing intentional disclosure and anonymous distribution of the key.

Using this scheme, the specific problem that needs to be solved is to ensure that the MBS server can obtain the MSS public key correctly and safely, because both the user and the attacker may generate a public key pair by themselves and send the public key in the key pair to For the MBS server, if the MBS cannot determine whether the public key matches the private key stored in the anti-tamper password module of the MSS device. When it encrypts the multicast broadcast service key with the public key and sends it to the user, the user or attacker can use the private key in the public key pair generated by itself to untangle the message to obtain the MBS service key.

Generally, the following two methods can be used to enable the MBS server to correctly and safely obtain the public key that matches the private key in the tamper-proof cryptographic module of the MSS device.

Embodiment 1: The method of setting the public key storehouse

MSS devices need to be registered in an MSS public key library (such as KDC: Key Distribution Center Key Distribution Center) before leaving the factory. The registered information includes a unique identification information and public key of the MSS. The public key library is set by an independent security center. And maintenance, the security center is specifically responsible for generating the public key and the private key, and loading the private key into the anti-tampering cryptographic module of the mobile station. When MSS performs authentication and key exchange with MBS, MSS sends its unique identification information to MBS, and MBS obtains MSS’s ID from MSS public key storehouse through the secure channel established with the security center according to this unique identification. public key, and use the public key to encrypt the MBS service key generated by it, and send the encrypted key information to MSS. After receiving the encrypted MBS service key information, MSS must send it to the defense Only by decrypting with its private key in the disassembled cryptographic module can the MBS service encryption key be obtained. After the MSS receives the encrypted MBS service data, it must also be sent to the cryptographic module for decryption. In this way, the user is prevented from directly touching the MBS service key, and the risk of the user intentionally leaking or anonymously distributing the MBS service encryption key is effectively reduced.

Embodiment 2: Method for issuing a public key digital certificate

Each MSS device obtains a digital certificate issued by the device supplier or other security certification center (CA: Certification Authority) after leaving the factory. The certificate contains the MSS public key and can also include a public key verification information. The MBS server uses the verification information to verify the validity of the public key. The MSS needs to send the digital certificate to the MBS server during the process of requesting the MBS server to obtain the MBS service key. After obtaining the digital certificate, the MBS server verifies the digital certificate to obtain the public key of the MSS, encrypts the MBS service key registered with the MSS with the public key of the MSS, and sends it to the MSS. After MSS obtains the encrypted service key information, it must be sent to the anti-disassembly cryptographic module and decrypted with its private key to obtain the MBS service encryption key. After the MSS receives the encrypted MBS service data, it must also be sent to the cryptographic module for decryption. In this way, the user is prevented from directly touching the MBS service key, and the risk of the user intentionally leaking or anonymously distributing the MBS service encryption key is effectively reduced.

The invention provides a control method to ensure the safe distribution of the MSS service key and prevent it from being intentionally leaked or anonymously distributed, and the method is applicable to all MBS services.

Claims (10)

1, a kind of packet broadcasting service key controlling method is characterized in that, comprises the following steps:

A: for travelling carriage is provided with PKI and corresponding private key thereof;

B: the multicast broadcast service Distributor utilizes described public key encryption packet broadcasting service key, and sends to travelling carriage;

C: the packet broadcasting service key that travelling carriage utilizes described private key deciphering to receive.

2, control method as claimed in claim 1 is characterized in that: described travelling carriage is provided with the tamper crypto module and preserves described private key.

3, control method as claimed in claim 2, it is characterized in that: packet broadcasting service key and preservation that described tamper crypto module utilizes described private key deciphering travelling carriage to receive, the group broadcasting broadcast business data that utilizes described packet broadcasting service key deciphering travelling carriage to receive.

4, control method as claimed in claim 3 is characterized in that: described PKI and private key are provided with by security centre independently, and by described security centre private key are saved in the tamper crypto module of travelling carriage.

5, control method as claimed in claim 4 is characterized in that: also comprise step between described steps A and the B:

A1: described security centre sets up the identification information and the corresponding PKI thereof of PKI storehouse registration travelling carriage.

6, control method as claimed in claim 5 is characterized in that, also comprises the following steps: between described steps A 1 and the B

Travelling carriage sends its identification information to the multicast broadcast service Distributor;

The multicast broadcast service Distributor is searched corresponding PKI according to the identification information of travelling carriage by escape way from described PKI storehouse.

7, control method as claimed in claim 6 is characterized in that, described identification information sends to the multicast broadcast service Distributor with the packet broadcasting service key request message of travelling carriage.

8, control method as claimed in claim 4 is characterized in that, also comprises step between described steps A and the B:

A1: by described security centre is that travelling carriage is signed and issued digital certificate, and described digital certificate comprises the PKI of travelling carriage.

9, control method as claimed in claim 8 is characterized in that, also comprises the following steps: between described step a1 and the B

Travelling carriage sends described digital certificate to the multicast broadcast service Distributor;

The multicast broadcast service Distributor is verified described digital certificate and is obtained the PKI of this travelling carriage.

10, control method as claimed in claim 9 is characterized in that: described digital certificate sends to the multicast broadcast service Distributor with the packet broadcasting service key request message of travelling carriage.

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