WO2007118387A1

WO2007118387A1 - A method and system for keeping digital rights management time synchronization

Info

Publication number: WO2007118387A1
Application number: PCT/CN2007/000076
Authority: WO
Inventors: Hailong Qi; Sheng Li
Original assignee: Huawei Technologies Co., Ltd
Priority date: 2006-04-18
Filing date: 2007-01-09
Publication date: 2007-10-25
Also published as: CN100470568C; CN101059825A

Abstract

A method and system for keeping Digital Rights Management time synchronization are provided. The method comprises: sending time synchronization request to a time synchronization reference device when a terminal device is powering-on; the time synchronization reference device sends synchronization time to the terminal device according to the time synchronization request; adjusting a secure time of the terminal device according to the received synchronization time. By the method and system, it is effectively resolved that time synchronization and accumulated error of maintaining secure time offset in OMA DRM2.0 when the device does not issue ROAP protocol. The invention implements secure clock by software without adding any hardware, so as to reduce the cost.

Description

Method and system for maintaining digital rights management time

This application claims priority to Chinese Patent Application No. 200610060427.6, entitled "Method and System for Maintaining Digital Rights Management Time Synchronization," filed on April 18, 2006, the entire contents of which are incorporated by reference. In this application.

Technical field

The present invention relates to Open Mobile Alliance digital rights management technology, and more particularly to an Open Mobile Alliance Digital Rights Management System (Open Mobile Alliance Digital Rights)

The Management System (hereinafter referred to as the OMA DRM system) provides a method and system for digital rights management to maintain time synchronization.

Background technique

Recently, copyright protection technologies such as the OMA DRM system have developed rapidly and are increasingly recognized. Copyright protection technology is mainly used to protect digital content including music, video, images, books, computer software, etc., mainly by restricting the use of digital content, copying, etc., to protect digital content.

In the OMA DRM 2.0 technology, _ controls the use of the digital content of the copyright object by the control parameters set in the Rights Object. For example, controlling the number of uses of digital content by the limit of counts in the rights object; by the expiration date in the copyright object

(datetime) restrictions to limit the use of digital content;

(accumulated) to limit the cumulative time length of use of digital content. The copyright object is an important part of copyright control in OMA DRM technology. In the above technical specification of OMA DRM2.0, it is necessary for the terminal to maintain a secure time for the validity period of the certificate of the terminal device, the time-related restriction parameter in the copyright object, and if the security time is lost, between the terminal and the server. When the RO AP (abbreviation of Rights Obj ect Acquisition Protocol, Protocol Object Acquisition Protocol) protocol is exchanged, the time synchronization operation is performed by the OCSP (abbreviation of Online Certificate Status Protocol), so that the terminal and the OCSP Responsder are in time. Synchronize. Figure 1 shows the 4-pass registration flow chart for the ROAP protocol. As shown in FIG. 1, the terminal device sends a greeting to the authorization center (step 101). After the authorization center receives the call, the authorization center sends a greeting response to the terminal device (step 102), and when the terminal device initiates a registration request to the authorization center (step 103), the authorization is authorized. The Rights Issuer will check if the safety time of the equipment brought by the terminal equipment is correct. If it is not correct, then The authorization center sends an OCSP request to the OCSP responder (step 104), and the OCSP responder sends an OCSP response (OCSP Response) to the authorization center (step 105), and the authorization center sends a registration response to the terminal. Equipment (step 1Q6). The OCSP response carries the standard time, and the terminal device performs the time synchronization operation according to the standard time in the OCSP response.

The 2-pass copyright acquisition process of the ROAP protocol is shown in Figure 2. The terminal device also carries the device security time in the RO request (RO 201) sent to the authorization center (step 201). The authorization center also judges whether the security time is correct (step 202). If it is determined that the security time is incorrect, an OCSP request is sent to the OCSP responder (step 203), and the OCSP response is received (step 204). The OCSP responds to the terminal device (step 205). The terminal device synchronizes according to the standard time in the OCSP response.

A common problem with the time synchronization schemes involved in 2-PASS and 4-PASS in OMA DRM2.Q above is that time synchronization is only performed when the terminal device initiates a ROAP protocol to the Rights Issuer. This leaves a hidden danger. For example, after obtaining some copyright objects, the user can no longer initiate the ROAP protocol, and the device security time changes by letting the device power down or other possible measures. At this time, when using digital content, the user can change the time to achieve the purpose of reusing the copyright object, and the copyright object has problems in controlling the use of the digital content.

In U.S. Patent No. 20050177513, entitled "Digital rights management method and system for content copyright protection", proposed by Kim Tae-sung, is referred to by a time. A time secure module is used to record the time modification information or time offset of the user to the terminal device. When the user uses the digital content, the time offset of the security device may be calculated according to the current time and time of the terminal device. A standard time is issued to ensure that the copyright control information of the digital content is effectively executed without being affected by the user's free time. For example, the current standard time is 13:00, and the current time of the user is also 13:00, and the user will The time is changed to 11:00, and two hours in advance, the time security module will record this time change amount (2 hours). When the terminal device time is displayed as 15:00, it can be recorded according to the time security module. Time modification information or time offset to determine the current standard time should 17:00.

With the above scheme, it is necessary to determine the difference between a standard time and the equipment time at the initial time, and when the user modifies the time, the time modification information recorded by the time security module will be tired. It may cause accumulation of errors and affect the accuracy of time. Moreover, once the time modification information maintained by the secure time module is lost, there is no effective means to recover. In addition, some terminal devices suddenly lose power, and after restarting, the time will automatically change to an initial time. For example, from 2005-9-28 to 2000-01-01. At this time, the change of time is that the system time changes after the power failure, and the time security module cannot record the time change amount, which causes the standard time calculated by the safety time module to be no longer accurate. Summary of the invention

The technical problem to be solved by the embodiments of the present invention is to propose a method and system for maintaining digital rights management time synchronization, and does not rely on the terminal device to initiate a ROAP protocol to the authorization center, so that the copyright object information of the DRM content can be managed and protected more effectively.

Embodiments of the present invention provide a method for maintaining digital rights management time synchronization, including the following steps:

When the terminal device is powered on, initiate a time synchronization request to the time synchronization reference device;

The time synchronization reference device sends a synchronization time to the terminal device according to the time synchronization request;

The security time information on the terminal device is corrected according to the received synchronization time. Correspondingly, an embodiment of the present invention provides a terminal device, including a synchronization request unit, a receiving unit, and a controller, where

The synchronization requesting unit is configured to send a time synchronization request to the time synchronization reference device; the receiving unit is configured to receive a synchronization time from the time synchronization reference device, and send the synchronization time to the controller;

The controller is configured to control the synchronization requesting unit to generate a time synchronization request when the terminal device is powered on; and correct the security time information on the terminal device according to the synchronization time received by the receiving unit.

The embodiment of the present invention further provides a system for maintaining digital rights management time synchronization, including a terminal device and a time synchronization reference device, where

And the terminal device is configured to initiate a time synchronization request to the time synchronization reference device, and correct the security time information on the terminal device according to the synchronization time from the time synchronization reference device;

The time synchronization reference device sends a synchronization to the terminal device according to the time synchronization request Time

The method and system for maintaining digital rights management time synchronization according to an embodiment of the present invention can significantly reduce the loss or tampering of the terminal security time by performing time synchronization between the terminal device and the time synchronization reference device at the time of power-on, and correcting the security time information of the terminal. Case. For example, the time synchronization problem when the terminal device does not initiate the ROAP protocol in OMA DRM2.0 can be effectively solved; the cumulative error problem in the maintenance security time offset is solved. A good solution for the more effective implementation of copyright information control in digital copyright protection technology is proposed. In the meantime, the method and system provided by the embodiments of the present invention can implement a secure clock through software without adding any hardware in the terminal device, and thus the cost is low.

DRAWINGS

1 is a schematic diagram of a registration process of a copyright object acquisition protocol ROAP 4-pass in the prior art; FIG. 2 is a schematic diagram of a copyright acquisition process of a copyright object acquisition protocol ROAP 2-pass in the prior art; FIG. 3 is a schematic diagram of a first embodiment of the present invention; Schematic diagram of a time synchronization process between a terminal device of a hardware clock and a base station;

4 is a schematic diagram of a time synchronization process performed between a terminal device without a hardware clock and a base station in a second embodiment of the present invention; a schematic diagram of a time synchronization process;

6 is a schematic diagram of a time synchronization process between a terminal device without a hardware clock and a time synchronization server in a fourth embodiment of the present invention; a schematic diagram of a time synchronization process between the devices;

FIG. 8 is a schematic diagram showing how a secure time is used when a terminal device having a hardware clock in a seventh embodiment of the present invention uses copyright;

FIG. 9 is a schematic diagram showing how a secure time is used when a terminal device without a hardware clock in the eighth embodiment of the present invention uses copyright.

FIG. 10 is a schematic structural diagram of a terminal device in a first embodiment of the present invention; FIG.

11 is a schematic structural diagram of a terminal device in a second embodiment of the present invention;

FIG. 12 is a schematic structural diagram of a terminal device according to Embodiment 3 of the present invention; FIG. FIG. 13 is a schematic structural diagram of a terminal device according to Embodiment 4 of the present invention; FIG.

Figure 14 is a block diagram showing the structure of a system for maintaining digital rights management time synchronization in the first embodiment of the present invention;

Figure 15 is a block diagram showing the structure of a system for maintaining digital rights management time synchronization in the second embodiment of the present invention;

Figure 16 is a block diagram showing the structure of a system for maintaining digital rights management time synchronization in the third embodiment of the present invention.

detailed description

Embodiments of the present invention are based on implementing a synchronization process with a time synchronization reference unit when the terminal device is powered on.

In the method for maintaining digital rights management time synchronization provided by the embodiment of the present invention, the synchronization refers to time synchronization between the secure time unit of the digital rights use terminal device and the time synchronization reference device of the authorization center, the premise is: A secure time unit is established on the terminal device, wherein the secure time unit in the terminal device has two types, one uses a hardware clock, and the other uses software time information, and the software time information includes a standard time or/and a time offset. The terminal device includes a mobile terminal and a network terminal, and the mobile terminal may be a mobile phone or the like, and the network terminal may be a PC or the like. Correspondingly, the time synchronization reference unit corresponding to the mobile terminal may be a time synchronization base station or a time synchronization server. The time synchronization reference unit corresponding to the network terminal is a time synchronization server. There are various methods for establishing a secure time unit. For example, the method of the secure time module proposed in the aforementioned patent US 2005Q177513 may be employed, or the method of adding a hardware clock may be implemented by maintaining the user's time information or other possible methods. .

On the basis of establishing a secure time unit of the terminal device, in order to maintain the time synchronization of the terminal device and the time synchronization reference device, it is necessary to specify that the terminal is set to be powered on, that is, the time synchronization program is started, in other words, between the terminal device and the time synchronization reference device. The synchronization process is activated or invoked by the terminal device when it is powered on or powered on. On the other hand, the power-on initialization process of the terminal device using the method of the present invention includes or embeds a process for time synchronization with the time synchronization reference device.

The result of the synchronization is that a standard time provided by the time synchronization reference device or a time offset reflecting the standard time is obtained. After the terminal device receives the standard time or reflects the time offset of the standard time, for the terminal device that uses the time modification information to maintain the time, each time synchronization is based on The standard time is used to update the time modification information; for the hardware clock, the time of the hardware clock is adjusted every time synchronization.

The method of the embodiment of the present invention includes at least three steps of providing a secure time unit, starting, synchronizing, and adjusting the secure time unit according to the time synchronization result. That is, the terminal device first needs to maintain a safe time through the security unit. The terminal device performs time synchronization operation each time the terminal device is powered on. The security time is updated and maintained in the following ways:

1) Synchronize time with the base station after the terminal device is powered on. The terminal device updates the standard time based on the latest synchronization time and reinitializes the time offset or adjusts the secure hardware clock.

2) Synchronize between the terminal device and the time synchronization server after booting. The terminal device updates the standard time based on the latest synchronization time and reinitializes the time offset or adjusts the secure hardware clock. In this time synchronization mode, time synchronization messages between the terminal device and the time synchronization server need to be secured to prevent malicious tampering. Security measures can be implemented using SSL or digital digests, signatures, and more. Or

3) The terminal device finds that the security time is lost. For example, if the time modification amount is lost, the time synchronization operation is initiated to the time synchronization server. The terminal device updates the standard time based on the latest synchronization time and reinitializes the time offset or adjusts the secure hardware clock.

Embodiments of the present invention cover both aspects of the time synchronization process and the use of copyright for secure time. Wherein: the time synchronization includes two terminal devices having a hardware clock and a hardware-free clock; and a mobile terminal or a network terminal corresponding to any clock with or without time, respectively performing time synchronization processing with two secure time reference devices of the base station and the time synchronization server Process.

The various embodiments of the present invention are further described below in conjunction with the flowcharts. FIG. 3 shows a first embodiment for explaining a time synchronization process between a terminal device having a hardware clock and a base station as a secure time reference device, wherein the terminal device is provided with a hardware clock 34, the hardware clock pair device The user cannot modify it. At the same time, the terminal device is provided with a secure time unit for recording the standard time or/and time offset of the device, and the terminal device including the secure time unit synchronizes with the time reference device at the time of power on. Time synchronization is performed as follows:

When the terminal device is powered on, the time synchronization process with the time synchronization base station is started immediately after the power is turned on (arrow 1 is shown). During the time synchronization process, the connection with the time synchronization base station is established according to the protocol, and the standard time provided by the time synchronization base station is read. On the basis of this, the terminal device initiates the correction of the safety time information in the safety time unit according to the time synchronization result, that is, the current standard time, that is, the safety time unit safety time information is corrected (indicated by arrow 2). This correction actually modifies the standard time that the hardware clock representing the secure time information in the secure clock unit in the terminal device provides the base station.

In the second embodiment of the method of the present invention shown in FIG. 4, the terminal device without the hardware clock immediately starts the time synchronization process with the base station (shown by arrow 1) after being turned on, and after obtaining the standard time with the base station, according to At this standard time, the terminal device initiates a correction to the safety time unit clock information (arrow 2). This correction actually modifies the time offset in the terminal security time unit.

In the third embodiment of the method of the present invention shown in FIG. 5, the terminal device with the hardware clock is powered on, and the time synchronization process with the time synchronization server is started immediately after power-on (shown by arrow 1), and the time synchronization process is from the time synchronization server. After the standard time is obtained, the terminal device initiates the correction of the hardware clock information in its secure time unit (indicated by arrow 2). This correction actually modifies the current time of the hardware clock in the secure clock unit of the terminal device to the standard time provided by the base station.

In the fourth embodiment of the method of the present invention shown in FIG. 6, the terminal device without the hardware clock is powered on, and the time synchronization process with the time synchronization server is started immediately after the power-on (shown by arrow 1), and the time synchronization process is synchronized from time. After the server obtains the standard time, the terminal device initiates the correction of its security time unit clock information (indicated by arrow 2). The correction actually modifies the time offset of the terminal device security clock unit based on the standard time from the time synchronization server.

7-9 illustrate how the terminal device uses the secure time after the terminal device completes the time synchronization. In the fifth embodiment of the method of the present invention shown in Fig. 7, the terminal device finds that the maintained security time information is lost, and initiates a time synchronization request to the time synchronization server (indicated by arrow 1). The terminal can check whether the time offset file or data exists, whether the security clock is initialized, etc. To determine if the safe time is lost. After the synchronization process with the time synchronization server is over, the terminal corrects its secure clock unit (shown by arrow 2), that is, after the synchronization is completed, the correction actually modifies the time offset of the device time security module. The technical solution of the embodiment is used to monitor the security time information of the maintenance. When the security time information is lost or incorrect, the time synchronization request is initiated, and the security time of the terminal is destroyed, such as power failure, data loss, etc. After that, it is difficult to re-establish the issue of a secure time base.

A sixth embodiment of the method of the present invention is used to describe how the terminal device acquires time synchronization. The following steps are given to obtain time synchronization:

1) When the device is powered on or considers that time synchronization is required, an NTP time synchronization protocol or a customized time synchronization protocol is initiated to the time synchronization server;

2) the time synchronization server responds to the protocol message, and sends the message with the accurate time to the device that initiates the time synchronization in a secure transmission manner;

3) The device receives the corresponding time response message and gets the exact time from it. Customized time Synchronization messages require secure transmission, such as SSL transmission, to prevent tombs during transit.

4) After the device has been accurately timed, compare it with the time information in the local safety time unit maintained; if the error between the two exceeds the allowable range, (according to the OMA DRM2.0 specification, the tolerance is l ² 0 ppm, That is, the tolerance for about one year is 60 minutes. The meaning of the unit ppm is: 1 second can have an error of parts per million), then the local safety time is considered invalid and needs to be updated. Due to the delay of network transmission and server processing, the time information sent by the time synchronization server generally includes a network transmission and processing delay during time synchronization. This delay time can be determined statistically after multiple tests according to the network conditions. The delay time is "a predetermined period of time" is a constant value. For example, the delay is 5ms from 14:00 to 17:00 in the afternoon. In 19:00~21:00, the delay time of this time period is 10ms. Then the server sends the value to the device during the synchronization time or the device stores and maintains the value. After receiving the time information, the device needs to This delay time adjusts the time to a relatively accurate time for reuse. The adjustment method is: Standard time = standard time received - delay time.

5), the device confirms that the current security time needs to be updated, adjusts the local security clock or updates the time offset information. After the time synchronization and local security time are correctly updated, the terminal device can use the digital content correctly and effectively according to the copyright information. To illustrate the flow of use of the method of the present invention, a seventh embodiment of the method of the present invention is discussed below in conjunction with FIG. After the start of block 801, the time of the secure clock is first obtained, as in block 802, prior to the use of the digital content, and at block 803, the time-dependent control in the copyright is calculated and maintained based on the secure time in the process of using the digital content. information. For example, it is judged whether the copyright validity period has expired, whether the copyright usage period has been used up, and the like. At the same time, the user's usage time information of the content is updated and maintained in the copyright. In the use of the content, if the copyright is found to have expired, the use of the content is terminated. Or the user actively stops using the content. Until the end of the digital content usage or the copyright has expired, the process ends at block 804.

To illustrate another flow of use of the method of the present invention, the eighth embodiment of the method of the present invention is discussed below in conjunction with FIG. After the start of block 901, prior to using the digital content, the time offset of the secure time module is first determined as in block 902; in the next block 903, the current standard time is calculated based on the time offset; in subsequent block 904 , means that in the process of using digital content, the time-related control information in the copyright is calculated and maintained according to the safe time. After calculating the standard time, for time-related copyright, for example, the validity period is valid from 2005-01-01 12:00 to 2005-01-02 13:00, it is judged according to the current standard time whether the validity period has expired or not yet Period to determine if it is available. This patent mainly provides a safe standard time to the DRM equipment, and how to use the standard time for copyright maintenance is no longer discussed. For example, it is judged whether the copyright validity period has expired, whether the copyright usage period has been used up, and the like. At the same time, the user's usage time information of the content is updated and maintained in the copyright; in addition, in the process of using the content, if the copyright is found to have expired, the content is terminated. Or the user actively stops using the content, as in box 905.

Correspondingly, referring to FIG. 10, an embodiment of the present invention provides a terminal device, including a synchronization request unit.

12. The receiving unit 13 and the controller 14, wherein the synchronization requesting unit 12 is configured to send a time synchronization request to the time synchronization reference device; the receiving unit 13 is configured to send the received synchronization time from the time synchronization reference device to the controller 14; when the terminal device is powered on, the controller 14 controls the synchronization requesting unit 12 to generate a time synchronization request; and corrects the security time information on the terminal device according to the synchronization time received by the receiving unit 13.

Further, referring to FIG. 11, a secure time unit 11 for storing safety time information is set, the controller 14 calls the safety time information in the safety time unit 11, and the safety time information is corrected according to the synchronization time, and will be corrected. The secure time information is sent to the secure time unit 11.

Referring to Figure 12, a comparator 15 is also included for comparing the synchronization time from the time synchronization reference device And the standard time in the safety time information, if the error of the two exceeds the allowable range, the correction control signal is sent to the controller 14, and the controller 14 corrects the safety time based on the correction control signal.

Referring to FIG. 13, in order to further improve the reliability of the security time of the terminal device, when the security time of the terminal device is destroyed, such as power failure or data loss or error, the detector 16 is further set to detect whether the security time information in the security time unit 11 is Loss or error, and send the detection result to the controller 14; after receiving the detection result of the lost or incorrect safety time information, the controller 14 controls the synchronization request unit 12 to generate a new time synchronization request.

Referring to FIG. 14, an embodiment of the present invention further provides a system for maintaining digital rights management time synchronization, including a terminal device 1 and a time synchronization reference device 2, wherein when the terminal device 1 is powered on, a time synchronization request is initiated to the time synchronization reference device 2. And correcting the secure time information on the terminal device 1 according to the synchronization time from the time synchronization reference device 2; the time synchronization reference device 2 transmits the synchronization time to the terminal device 1 according to the time synchronization request from the terminal device 1. The terminal device 1 is the same as the aforementioned terminal device, and details are not described herein again.

Referring to Fig. 15, the time synchronization reference device 2 includes a response unit 21 and a standard unit 22, wherein the _ response unit 21 generates a response message to the standard unit 22 based on the time synchronization request from the synchronization request unit 12; the standard unit 22 is based on the response unit The response message of 22 acquires the synchronization time and sends it to the receiving unit 13.

The terminal device 1 includes a mobile terminal and a network terminal, and the mobile terminal can be a mobile phone or the like. The network terminal can be a PC or the like. Correspondingly, the time synchronization reference unit 2 corresponding to the mobile terminal can be a time synchronization base station or a time synchronization server. The time synchronization reference unit 2 corresponding to the network terminal is a time synchronization server.

Referring to FIG. 16, in order to improve the security during the synchronization time transmission, the decoder 15 is further disposed in the terminal device 1, and the encoder 23 is further provided in the time synchronization reference device 2, and the encoder 23 is set at the synchronization time acquired by the standard unit 22. After the SSL or digital digest, digital signature, the synchronization time of the security protection is sent to the decoder 15; the decoder 15 obtains the synchronization time from the synchronization time of the security protection, and then sends it to the receiving unit 13. The description of the examples is only to assist in understanding the method of the present invention and its core idea, in accordance with the idea of the present invention, The details of the present invention and the scope of the application are subject to change. The contents of the present specification are not to be construed as limiting the invention.

Claims

Rights request

A method for maintaining digital rights management time synchronization, comprising the steps of: initiating a time synchronization request to a time synchronization reference device when the terminal device is powered on;

The security time information on the terminal device is corrected according to the received synchronization time.

The method according to claim 1, wherein the time synchronization reference device comprises a time synchronization base station or a time synchronization server.

3. Method according to claim 1 or 2, characterized in that the safety time information comprises a standard time and/or a time offset.

The method according to claim 3, wherein the step of modifying the security time information on the terminal device according to the received synchronization time comprises:

And updating the standard time on the terminal device, initializing the time offset on the terminal device, or adjusting the time of the hardware clock on the terminal device according to the synchronization time.

5. The method according to claim 4, further comprising: determining an allowable range, and determining that the security time information on the terminal device needs to be corrected.

6. The method according to claim 2, further comprising:

When the time synchronization reference device is a time synchronization server, the synchronization time is securely protected.

The method according to claim 6, wherein the method for implementing security protection comprises:

Set SSL or digital digest, digital signature on the synchronization time.

8. The method according to claim 1, further comprising:

The terminal device detects whether the security time information is lost or incorrect. If the security time information is lost or incorrect, the terminal device initiates a new time synchronization request to the time synchronization reference device.

The time synchronization reference device sends a new synchronization time to the terminal device according to the new time synchronization request; The security time information on the terminal device is corrected according to the received new synchronization time.

A terminal device, comprising: a synchronization request unit (12), a receiving unit (13), and a controller (14), wherein

The synchronization requesting unit (12) is configured to send a time synchronization request to the time synchronization reference device; the receiving unit (13) is configured to receive a synchronization time from the time synchronization reference device, and send the synchronization time to the controller (14) ) ;

The controller (14) is configured to control the synchronization requesting unit (12) to generate a time synchronization request when the terminal device is powered on; and correct the terminal device according to the synchronization time received by the receiving unit (13) Safety time information.

10. The terminal device according to claim 9, further comprising: a security time unit

(11), the safety time unit is configured to store safety time information, the controller (14) invokes safety time information in the safety time unit (11), and corrects the safety time information according to the synchronization time, The corrected safety time information is sent to the secure time unit (11).

The terminal device according to claim 10, further comprising: a comparator (15), wherein said comparator (15) compares a synchronization time from said time synchronization reference device with said safety time information The standard time, if the error of the two exceeds the allowable range, sends a positive control signal to the controller (14), and the controller (14) corrects the safety time information according to the correction control signal.

The terminal device according to claim 10 or 11, characterized by: further comprising a detector (16), the detector (16) detecting whether the safety time information in the safety time unit (11) is lost or If there is an error, the detection result is sent to the controller (14), and the controller (14) controls the synchronization request unit (12) to generate a new one after receiving the detection result that the safety time information is lost or is incorrect. Time synchronization request.

13. A system for maintaining digital rights management time synchronization, comprising: a terminal device (1) and a time synchronization reference device (2), wherein

When the terminal device (1) is used for powering on, initiates a time synchronization request to the time synchronization reference device (2), and corrects the terminal device according to a synchronization time from the time synchronization reference device (2) (1) Safety time information on;

The time synchronization reference device (2) according to the time synchronization request to the terminal device (1) Send synchronization time.

The system according to claim 13, characterized in that: the terminal device (1) comprises a synchronization request unit (12), a receiving unit (13) and a controller (14), wherein

The synchronization request unit (12-) is configured to send a time synchronization request to the time synchronization reference device; the receiving unit U3) is configured to receive a synchronization time from the time synchronization reference device, and send the synchronization time to the controller (14) ) ;

The system according to claim 14, characterized in that said time synchronization reference device (2) comprises a response unit (21) and a standard unit (22), wherein

The response unit (21) is configured to generate a response message to the standard unit (22) according to a time synchronization request from the synchronization request unit (12);

The standard unit (22) acquires a synchronization time based on a response message from the response unit (22) and transmits it to the receiving unit (13).

The system according to claim 15, wherein: said terminal device (1) further comprises a decoder (15), said time synchronization reference device (2) further comprising an encoder (23),

The encoder (23) obtains a synchronization time of security protection after setting SSL or digital digest, digital signature on the synchronization time acquired by the standard unit (22), and sends the synchronization time to the decoder (15); the decoder ( 15) After obtaining the synchronization time from the synchronization time of the security protection, sending the synchronization time to the receiving unit (13).