CN101945243B

CN101945243B - Computing method of safety clock and terminal

Info

Publication number: CN101945243B
Application number: CN201010257646.XA
Authority: CN
Inventors: 梁洁辉; 施元庆; 彭叶斌
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2010-08-16
Filing date: 2010-08-16
Publication date: 2014-07-16
Anticipated expiration: 2030-08-16
Also published as: CN101945243A; WO2012022197A1

Abstract

The invention discloses a computing method of a safety clock, comprising the following steps: when watching the TV programs protected by digital rights management (DRM), a terminal computes the safety clock according to the difference between two latest obtained TV clocks, the difference between the two-time latest recorded boot time and the obtained DRM time. The invention also provides the terminal. The safety clock of the terminal is simply and rapidly updated according to the technical scheme of the invention.

Description

Computing method of secure clock and terminal

Technical Field

The invention relates to the field of mobile phone television services of terminals, in particular to a method for calculating a safety clock and a terminal.

Background

The Digital Video Broadcasting-Handheld (DVB-H) standard is a transmission standard specified by the Digital Video Broadcasting (DVB) organization for providing multimedia services to terminals through a terrestrial Digital Broadcasting network, and mobile televisions of this system were formally adopted by the European Telecommunications Standards Institute (ETSI) in 11 months in 2004 and are widely used in countries in europe, asia, and africa. When using the mobile phone television service, an operator of the mobile phone television service needs to ensure that a user of the mobile phone television service of the DVB-H system who pays normally can see the disturbed flow programs except the disturbed flow programs, and also needs to ensure that a user who pays abnormally can only see the disturbed flow programs, and the user needs to go to a communication operator website to purchase when watching the disturbed flow programs; therefore, it is necessary to protect the content of the mobile phone television to prevent the user who does not pay the normal fee from watching the scrambled stream program for no charge. In the prior art, the content of the mobile phone television is mainly protected by two ways: a conditional access system and a digital rights management system; the Conditional Access system may be a navaj (navajca) and an edid (irdeoppondication Access) system, and the Digital Rights Management system may be a V2.0 version of an Open Mobile Alliance Digital Rights Management (DRM) system.

When the content of the mobile TV is protected by using the method of the OMA DRM system, a clock is needed in the DVB-H terminal to judge whether a copyright object (RO) of the mobile TV acquired by a user is in a valid period, and the clock is a safe clock; the safety clock needs to be continuously synchronized with the network, and the user is not allowed to modify the time of the clock or the crystal oscillator number of the clock at will; the secure clock synchronizes with the network through a device registration process of a Rights Object Acquisition Protocol (ROAP), and after a user acquires an RO, if the device registration process of the ROAP is not performed any more, a situation that the mobile phone television content protected by the DRM can be unlimitedly used occurs. In the prior art, there is a method for implementing a secure clock by offsetting the current device time of a mobile terminal using a mobile tv and the device time during a registration process, which is feasible if a user does not change the system time of the mobile terminal; however, when the user modifies the system time or the system time is abnormal, the condition that the RO is abused still occurs; for example, the mobile television content purchased by the user is due at 8/1/2010, the current time is 8/2/2010, and the user adjusts the system time of the mobile terminal to any day before the 8/1/2010, so that the mobile terminal can still play the scrambled stream. In addition, there is another method for synchronizing with a Network clock source through a Network clock Protocol (NTP), which requires the mobile terminal to constantly maintain communication with the Network, thereby greatly increasing power consumption and usability of the mobile terminal.

Disclosure of Invention

In view of the above, the main objective of the present invention is to provide a method for calculating a secure clock and a terminal, which are capable of updating the secure clock of the terminal simply and quickly.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the invention provides a computing method of a secure clock, which comprises the following steps:

when watching a television program protected by Digital Rights Management (DRM), the terminal calculates a security clock according to the difference between two latest acquired television clocks, the difference between two latest recorded boot times and the acquired DRM time.

In the above method, the step of calculating, by the terminal, the secure clock according to the difference between the two latest acquired television clocks, the difference between the two latest recorded boot times, and the acquired DRM time further includes:

and after the terminal is started, the terminal records the starting time and acquires the television clock, and stores the recorded starting time and the acquired television clock.

In the above method, the recording of the boot time and the acquisition of the television clock by the terminal specifically includes:

a DRM module of the terminal acquires the time after the physical layer is synchronized with a DVB-H standard mobile phone television signal transmitting station through an interface of a chip of the physical layer for receiving television signals, wherein the time is a television clock; and after the terminal is started, the DRM module immediately records the current time of the terminal, and the time is the starting time.

In the above method, after the terminal is turned on, the step of recording the turn-on time and acquiring the tv clock by the terminal further includes:

and the terminal registers to the DRM server, acquires and stores the current DRM time.

In the above method, the registering of the terminal with the DRM server to obtain the current DRM time and store the current DRM time specifically includes:

a registration module of the terminal sends a greeting message to a DRM server, and the DRM server sends a DRM version and a trusted certificate authority encrypted by an encryption algorithm to the registration module through a reply message of the greeting message; the registration module sends the encrypted security clock and the encrypted certificate chain to the DRM server through a request message; the DRM server sends a registration response message carrying the current DRM time to a registration module; the registration module saves the current DRM time to the storage module of the terminal.

In the method, the terminal calculates the secure clock according to the difference between two latest acquired television clocks, the difference between two latest recorded boot times and the acquired DRM time specifically as follows:

and a computing module of the terminal computes the difference between the two latest acquired television clocks and the difference between the two latest acquired boot time stored in the storage module, and adds the difference between the two television clocks, the difference between the two boot time and the acquired DRM time to obtain the secure clock.

In the above method, the method further comprises:

calculating an absolute value of a difference between a Rights Object (RO) expiration time and a secure clock, comparing the absolute value with a validity period, and if the absolute value is less than the validity period, agreeing to view a television program protected by DRM; and if the absolute value is greater than the validity period, prompting to renew the mobile phone television service protected by the DRM.

The present invention also provides a terminal, including: the device comprises a storage module and a calculation module; wherein,

the storage module is used for storing the acquired television clock, the recorded starting time and the acquired DRM time;

and the computing module is used for computing the safety clock according to the difference of two latest acquired television clocks, the difference of two latest recorded boot time and the acquired DRM time when the television program protected by the DRM is watched.

In the above terminal, the terminal further includes: a registration module and a DRM module; wherein,

the register module is used for registering to the DRM server, acquiring the current DRM time and storing the current DRM time to the storage module;

and the DRM module is used for recording the starting time and acquiring the television clock after the terminal is started, and storing the recorded starting time and the acquired television clock in the storage module.

In the above terminal, the terminal further includes:

the valid period management module is used for calculating the absolute value of the difference between the RO expiration time and the safety clock, comparing the absolute value with the valid period, and if the absolute value is less than the valid period, agreeing to watch the television program protected by the DRM; and if the absolute value is greater than the validity period, prompting to renew the mobile phone television service protected by the DRM.

According to the calculation method and the terminal of the safe clock, the safe clock is calculated according to the difference of two latest acquired television clocks, the difference of two latest recorded boot time and the acquired DRM time, the interaction between the terminal and a network when the safe time is synchronized is effectively reduced, and the terminal only needs to be deployed, so that the time synchronization of the safe clock in the terminal and a DRM server is simply and quickly realized; in addition, as long as the television program protected by the DRM is watched, the calculation of the security clock is needed, and whether the validity period expires is judged by using the calculated security clock, so that the condition that the television program protected by the DRM is watched without limit because the user does not perform the equipment registration process of the ROAP any more is avoided.

Drawings

FIG. 1 is a flow chart of a computing method for implementing a secure clock according to the present invention;

fig. 2 is a schematic structural diagram of the terminal of the present invention.

Detailed Description

The basic idea of the invention is: when watching a television program protected by Digital Rights Management (DRM), the terminal calculates a security clock according to the difference between two latest acquired television clocks, the difference between two latest recorded boot times and the acquired DRM time.

The invention is further described in detail below with reference to the drawings and the specific embodiments.

The terminal in this embodiment is a terminal of a mobile television supporting the DVB-H standard, for example, a mobile terminal, an MP4 handheld television, a GPS handheld television, or the like capable of receiving a mobile television signal of the DVB-H standard.

The invention provides a method for calculating a secure clock, and fig. 1 is a schematic flow chart of the method for calculating the secure clock, and as shown in fig. 1, the method comprises the following steps:

step 101, a terminal registers to a DRM server, acquires and stores the current DRM time;

specifically, when the terminal communicates with the DRM server, that is, a copyright holder of the mobile television service for the first time or when the RO expires, a registration process needs to be initiated to the DRM server, where the process specifically is as follows: a registration module of a terminal sends a greeting message to a DRM server, wherein the greeting message carries information of the terminal, the information comprises an International Mobile Subscriber Identity (IMSI) of an SIM card in the terminal and versions of DRM which can be supported by the terminal, and the existing versions of DRM comprise versions 1.0, 2.0 and 2.1; after receiving the greeting message, the DRM server selects the version number of the DRM version corresponding to the DRM version number according to the DRM version supported by the terminal, and sends the version number of the DRM version encrypted by using an encryption algorithm and a trusted certificate authority to a registration module of the terminal where the SIM card corresponding to the IMSI in the greeting message is located through a reply message of the greeting message; after receiving the reply message, the registration module firstly judges whether the version number of the version of the DRM which can be supported by the terminal is consistent with the received version number, if so, the registration module utilizes a pre-stored device private key to carry out encryption operation on a current security clock and a certificate chain corresponding to a trusted certificate authority, and sends the encrypted security clock and the encrypted certificate chain to the DRM server through a request message; if not, the registration fails, and the current flow is ended; when the terminal is started every time, the DRM module records the current starting time, calculates the difference value of the two starting times which is closest to the time of registering the terminal to the DRM server, and the registering module acquires the difference value from the DRM module; when the terminal is started each time, the physical layer of the terminal can carry out time synchronization with the transmitting station; the registration module adds the acquired difference value to the time after the last physical layer synchronization to obtain a current safe clock; the certificate chain approved by the DRM server comprises a device certificate, a device private key, an operator certificate and a root certificate of a certificate authority, wherein the device certificate, the device private key, the operator certificate and the root certificate are purchased by the terminal from a trusted certificate authority;

after receiving the request message sent by the registration module, the DRM server judges whether the certificate chain carried by the DRM server is consistent with the certificate chain stored by the DRM server and the time of the security clock is consistent with the time of the DRM server, if one item is inconsistent or both items are inconsistent, the DRM server sends a request to a trusted certificate authority, and after receiving the request, the trusted certificate authority sends the certificate chain of the DRM server and the current DRM time to the DRM server; the DRM server sends a registration response message carrying the current DRM time and the certificate chain to a registration module; the registration module stores the current DRM time to a storage module of the terminal and replaces the original certificate chain with the received certificate chain; the storage module can be a memory of the terminal, a FLASH memory or a file system; if the two items are consistent, the registration response message returned by the DRM server does not carry any information, and after the registration module receives the empty registration response message, the time of the terminal is confirmed to be consistent with the current DRM time; after that, the calculation of the secure clock of the terminal needs to be implemented using the DRM time as a base time.

Step 102, after the terminal is started, the terminal records the starting time and acquires a television clock, and stores the recorded starting time and the acquired television clock;

specifically, a DVB-H mobile television signal transmitting station distributes information of an Electronic Service Guide (ESG) through a broadcast channel, and the information is updated every day; after the terminal is started each time, a physical layer of the terminal immediately initiates a downloading flow of ESG information, a DVB-H mobile TV signal transmitting station transmits the ESG information to the physical layer of the terminal through a broadcast channel, and the information comprises channel information, a program list and the like of a mobile TV; when the ESG information is sent, the physical layer of the terminal can carry out time synchronization with a transmitting station, and a DRM module of the terminal obtains the time after the physical layer is synchronized through an interface of a chip of the physical layer for receiving television signals, wherein the time is a television clock; after the terminal is started, a DRM module of the terminal immediately records the current time of the terminal, wherein the time is the starting time; and the DRM module of the terminal stores the acquired television clock and the recorded startup time into a television clock table and a startup time table of a storage module of the terminal, and the sequence of the storage is determined according to the acquired sequence.

103, when watching the television program protected by the DRM, the terminal calculates a safety clock according to the difference of two latest acquired television clocks, the difference of two latest recorded boot time and the acquired DRM time;

specifically, each time a television program protected by DRM is watched, a registration module of the terminal firstly judges whether to register with the DRM server according to whether a secure clock is stored in a storage module, and if the secure clock is stored in the terminal and the registration is carried out, the secure clock is triggered to calculate the secure clock by the calculation module; if no registration is made, the terminal has no information of the secure clock and directly executes step 101.

And the calculation module of the terminal calculates the difference between the two latest acquired television clocks and the difference between the two latest acquired startup times stored in the storage module according to the sequence of the television clocks and the startup clocks stored in the television clock table and the startup time table in the storage module, adds the difference between the two latest acquired television clocks, the difference between the two startup times and the acquired DRM time to obtain a safety clock, and sends the safety clock to the validity period management module of the terminal.

Step 104, calculating the absolute value of the difference between the RO expiration time and the safety clock, comparing the absolute value with the validity period, executing step 105 if the absolute value is less than the validity period, and executing step 106 if the absolute value is greater than the validity period;

specifically, the validity period management module of the terminal calculates an absolute value of a difference between the RO expiration time and the secure clock, compares the absolute value with the validity period, and if the absolute value is less than the validity period, it indicates that the RO is valid, executes step 105; if the absolute value is greater than the validity period, indicating that the RO is expired, go to step 106; wherein the RO expiration time and the validity period are acquired from the DRM server and stored in the storage module after the registration module completes the registration process with the DRM server.

Step 105, agreeing to watch the television program protected by DRM;

specifically, the validity period management module of the terminal agrees that the user normally watches the television program protected by the DRM.

Step 106, prompting to renew the mobile phone television service protected by DRM, and executing step 101;

specifically, the validity period management module prompts the user to renew the mobile phone television service protected by DRM, and step 101 is executed.

In order to implement the above method, the present invention further provides a terminal, fig. 2 is a schematic structural diagram of the terminal of the present invention, and as shown in fig. 2, the terminal includes: a storage module 21 and a calculation module 22; wherein,

the storage module 21 is used for storing the acquired television clock, the recorded starting time and the acquired DRM time; the storage module 21 may be a memory of the terminal, a FLASH memory or a file system;

and the calculating module 22 is configured to calculate the secure clock according to the difference between the two latest acquired television clocks, the difference between the two latest recorded boot times, and the acquired DRM time when the television program protected by DRM is watched.

The terminal further includes: a registration module 23, a DRM module 24; wherein,

a registration module 23, configured to register with the DRM server, obtain a current DRM time, and store the current DRM time in the storage module 21;

the DRM module 24 is configured to record the boot time and obtain the television clock after the terminal is started, and store the recorded boot time and the obtained television clock in the storage module 21.

The terminal further includes:

a valid period management module 25, configured to calculate an absolute value of a difference between the RO expiration time and the secure clock, compare the absolute value with the valid period, and if the absolute value is smaller than the valid period, agree to watch a television program protected by DRM; and if the absolute value is greater than the validity period, prompting to renew the mobile phone television service protected by the DRM.

The DRM module 24 records the boot time and obtains the tv clock specifically as follows: a DRM module 24 of the terminal acquires the time after the physical layer is synchronized with a DVB-H standard mobile phone television signal transmitting station through an interface of a chip of the physical layer for receiving television signals, wherein the time is a television clock; after the terminal is turned on, the DRM module 24 immediately records the current terminal time, which is the turn-on time.

The registering module 23 registers with the DRM server, obtains the current DRM time, and stores the current DRM time in the storage module 21 specifically as follows:

the registration module 23 of the terminal sends a greeting message to the DRM server, and the DRM server sends the version number of the DRM version and the trusted certificate authority encrypted by the encryption algorithm to the registration module 23 through a reply message of the greeting message; the registration module 23 sends the encrypted secure clock and certificate chain to the DRM server through a request message; the DRM server sends a registration response message carrying the current DRM time to the registration module 23; the registration module 23 saves the current DRM time to the storage module 21.

The calculating module 22 calculates the security clock according to the difference between the two latest acquired television clocks, the difference between the two latest recorded boot times, and the acquired DRM time, specifically:

the calculation module 22 of the terminal calculates the difference between the two newly acquired television clocks and the difference between the two newly acquired boot times stored in the storage module 21, adds the difference between the two television clocks, the difference between the two boot times, and the acquired DRM time to obtain a secure clock, and sends the secure clock to the validity period management module 25.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, and any modifications, equivalents, improvements, etc. that are within the spirit and principle of the present invention should be included in the present invention.

Claims

1. A method of computing a secure clock, the method comprising:

the terminal registers to a Digital Rights Management (DRM) server, acquires and stores the current DRM time;

after the terminal is started, the terminal records the starting time and acquires a television clock, and stores the recorded starting time and the acquired television clock;

when watching the television program protected by DRM, the terminal adds the difference of two latest acquired television clocks, the difference of two latest recorded starting times and the acquired DRM time to calculate a safe clock;

the television clock is the time after the DRM module of the terminal acquires the synchronization between the physical layer and the DVB-H mobile television signal transmitting station through the interface of the chip of the physical layer for receiving the television signal; the starting time is the time of the current terminal immediately recorded by the DRM module after the terminal is started; and the DRM time is the time of the current DRM server obtained by registering the terminal to the DRM server.

2. The method according to claim 1, wherein the registering of the terminal with the DRM server, obtaining and storing the current DRM time specifically comprises:

3. The method according to claim 1, wherein the terminal recording the boot-up time and obtaining the television clock specifically comprises:

4. A method according to any one of claims 1 to 3, characterized in that the method further comprises:

5. A terminal, characterized in that the terminal comprises: the device comprises a registration module, a DRM module, a storage module and a calculation module; wherein,

the DRM module is used for recording the starting time and acquiring the television clock after the terminal is started, and storing the recorded starting time and the acquired television clock to the storage module;

the computing module is used for adding the difference of two latest acquired television clocks, the difference of two latest recorded boot time and the acquired DRM time when watching the television program protected by the DRM, and computing a safe clock;

6. The terminal of claim 5, further comprising: