WO2014088401A1

WO2014088401A1 - System and method for verifying authenticity of a media content

Info

Publication number: WO2014088401A1
Application number: PCT/MY2013/000223
Authority: WO
Inventors: Su Fong Chien; Geong Sen POH; Khong Neng Choong
Original assignee: Mimos Bhd.
Priority date: 2012-12-07
Filing date: 2013-12-03
Publication date: 2014-06-12
Also published as: MY168873A

Abstract

The present invention relates to a system (10) for authenticating a media content comprising: a main server (1) for distributing the media content; and at least a client (3) connected to the main server (1) for receiving the media content, characterized in that the system further comprising: a verifier generator (4) operating with the main server (1) for generating key parameter values to extract source verifier data from the media content, wherein the generated key parameter values and source verifier data are sent to the client (3) for authenticating the media content; and a verifier extractor (5) operating with the client (3) for extracting client verifier data from the received media content based on the key parameter values generated by the verifier generator (4), wherein the client verifier data are compared with the source verifier data received from the main server (1) for determining the authenticity of the media content.

Description

SYSTEM AND METHOD FOR VERIFYING AUTHENTICITY OF A MEDIA

CONTENT

Field of the invention

The present invention relates to the field of media content distribution in a network, and more particularly relates to a system and method for authenticating video content distributed via sub-servers by comparing the verifier data generated from the video frame.

Background of the invention

Multimedia content nowadays are being distributed to the end users in a number of ways including broadcast networks, the Internet, Internet Protocol television, and mobile network. Often, due to the heavy load of the media content and the limited bandwidth, utilization of sub-servers is inevitable in the distribution network. In fact, the content provider usually directs delivery of the media content to the end users via one or more sub-servers in order to conserve bandwidth. An issue of concern is that the media content may be modified by the non-trusted sub-servers when the main media server authorizes the sub-servers to distribute the media content. As a consequence, the integrity of the media content may be jeopardized and appear different from the intended result. Therefore, it is essential to ensure that the media content from the content provider is unmodified when being delivered via one or more sub-servers to the end users.

United States Patent No. 7593543 B1 discloses a method for detecting the distribution of video content by embedding watermarks in the form of pixels. The watermarks are embedded by the sub-servers each time the video content is transmitted via a sub-server. The accumulated watermarks then provide information to the distribution of the video content. Detection of the watermarks in the distributed video can prove to be a complicated process and may add additional cost for implementing the method. United States Patent No. 7933407 B2 discloses a method for verifying the authenticity of digital video frames by embedding a digital signature on each video frame based on a secret key and the immediately preceding frame. The video frames are first decompressed and decoded before embedding with the digital signature. A frame signature extracting unit extracts the digital signature of the frames so that the authenticity can be determined. The disclosed method involves a complicated and tedious process for embedding and subsequent extraction of the digital signatures for determining authenticity of the media content and thus is inefficient to be used in the industry.

United States Patent No. 8005216 B1 discloses a method for ensuring authenticity when transferring a video file. The method involves producing an encryption header for the video file which contains information for decrypting the video file. An encryption key is generated from a master key identified in the encryption header, which allows encryption of the file packet of the video content. Non-disposable sequence numbers are assigned to the file packet by computation. This disclosed method requires a large amount of complex computation for encryption and decryption of the video file. The complicated calculation renders the distribution process inefficient due to the time-consuming computations.

Accordingly, it can be seen that there is a need to provide a system and method for ensuring the authenticity of media content being distributed to the end users which does not require additional cost and complicated computation. Summary of the invention

It is an object of the present invention to provide a system and method for verifying the authenticity of a media content distributed in a network, wherein the media content is transmitted to client via one or more sub-servers.

It is yet another object of the present invention to provide a method for generating verifier data from a media content for detecting modification on the media content. It is another object of the present invention to provide a method for detecting modification on the transmitted media content with a simplified computation at the main server and client platform. It is another object of the present invention to provide a method for generating numerical verifier data based on calculations of pixel values in the video frame.

The present invention relates to a system for authenticating a media content comprising: a main server for distributing the media content; and at least a client connected to the main server for receiving the media content, characterized in that the system further comprising: a verifier generator operating with the main server for generating key parameter values to extract source verifier data from the media content, wherein the generated key parameter values and source verifier data are sent to the client for authenticating the media content; and a verifier extractor operating with the client for extracting client verifier data from the received media content based on the key parameter values generated by the verifier generator, wherein the client verifier data are compared with the source verifier data received from the main server for determining the authenticity of the media content. Further, the present invention relates to a method for authenticating a media content distributed from a main server to a client, characterized by the steps of: providing the media content to the main server; generating key parameter values and extracting a source verifier data from the media content based on the key parameter values by a verifier generator at the main server; sending the key parameter values and the source verifier data to the client; transmitting the media content to the client via the sub-server; extracting a client verifier data from the media content based on the received key parameter values when the media content is received by the client; determining authenticity of the media content by comparing the source verifier data and the client verifier data, wherein the media content is deemed modified when the client verifier data does not match the source verifier data. Brief descriptions of drawings

Figure 1 is a diagram showing a system for distributing a media content according to the present invention.

Figure 2 is a schematic diagram showing a system for distributing a media content and delivering key parameter values and verifier data, employing a verifier generator and a verifier extractor according to the present invention. Figure 3 is a flow chart showing the process for distributing and authenticating the media content according to the present invention.

Figure 4 is a flow chart showing the process for extracting verifier data from the media content according to the present invention.

Detailed Description of the Invention

The present invention will now be described in more detail with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

The present invention is a system (10) for authenticating a media content comprising a main server (1 ) for distributing the media content and at least a client (3) connected to the main server (1 ) for receiving the media content, characterized in that the system further comprising a verifier generator (4) operating with the main server (1 ) for generating key parameter values to extract source verifier data from the media content, wherein the generated key parameter values and source verifier data are sent to the client (3) for authenticating the media content. The system further comprising a verifier extractor (5) operating with the client (3) for extracting client verifier data from the received media content based on the key parameter values generated by the verifier generator (4), wherein the client verifier data are compared with the source verifier data received from the main server (1 ) for determining the authenticity of the media content.

With reference to Figure 1 , the main server (1 ) is connected to the sub-server (2) and the client (3). It can be seen that the media content can be delivered to the client (3) directly from the main server (1 ). In an alternative embodiment, the main server (1 ) can also direct delivery of the media content to the client (3) via the sub- server (2), in order to conserve bandwidth. However, problems arise when the assigned sub-server (2) is a non-trusted sub-server and may attempt to modify the media content when the media content is being transmitted to the client (3).

Figure 2 illustrates the use of the verifier generator (4) and the verifier extractor (5) in the system of the present invention for authenticating the media content. As shown in the Figure 2, the verifier generator (4) operates in association with the main server (1 ) for generating key parameter values. The generated key parameter values are used to extract source verifier data from the media content at the main server (1 ). In a preferred embodiment, the key parameter values and the source verifier data are sent directly to the client (3) and stored in the client (3) platform until the media content has been received. In a preferred embodiment, the media content is transmitted from the main server (1 ) to the client (3) via at least one sub-server (2). When the media content is received by the client (3), the verifier extractor (5) operates in association with the client (3) for extracting client verifier data from the received media content based on the key parameter values sent from the main server (1 ). The client verifier data can then be compared with the source verifier data to determine whether the media content has been tampered. In a preferred embodiment, the main server (1 ), the sub-server (2), and the client (3) are connected via a secured communication channel such that no intervention and modification on the media content can occur. The method of authenticating the media content generally involves extracting source verifier data before the media content is transmitted to the client (3), and then extracting client verifier data after the media content has been received by the client (3). A comparison between the source verifier data and the client verifier data is then performed to detect any discrepancy between them. The media content is deemed to be modified when the client verifier data does not match the source verifier data and as a result, the media content is then rejected.

In a preferred embodiment, the media content is a video content comprising a plurality of video frames with a threshold value. The video frames are grouped in blocks of pixels in rows and columns. In a more preferred embodiment, the video frames are intraframes (i-frames) which are in effect fully specified still images in a compressed digital video in which the numerical values can be obtained from the pixels for computer calculation. In a preferred embodiment, the threshold value, the number of rows, and number of columns are the key parameter values which are used for extracting verifier data.

Figure 3 shows a preferred exemplary implementation of the method of the present invention. At the request of the client (3) for streaming of pre-recorded video from the main server (1 ), a secured communication is established between the main server (1 ) and the client (3) when both sides verify the connection. The verifier generator (4) operating with the main server (1 ) proceeds to generate three key parameter values, namely number of rows of pixel blocks, number of columns of pixel blocks, and a threshold value. Based on the key parameter values, the verifier generator (4) extracts source verifier data from the video content according to a formula revolving the pixel values. The main server (1 ) then sends the key parameter values and the source verifier data to the client (3) via the secured communication channel. The key parameter values and the source verifier data are stored in the client (3) platform for subsequent operation when the video content is received. If the main server (1 ) decides that the bandwidth needs to be conserved, the video content is delivered to the sub-server (2) and the client (3) is notified to switch to the sub- server (2). The sub-server (2) and the client (3) then verify the connection to establish a secure communication channel.

The video content is then delivered to the client (3) from the sub-server (2). Upon receipt of the video content at the client (3), the verifier extractor (5) obtains the client verifier data from the received video content based on the stored key parameter values, in a same manner as how the source verifier data is obtained in the main server (1 ). The client verifier data obtained is then compared with the stored source verifier data to determine the authenticity of the video content. If the client verifier data does not match the source verifier data, the video content is deemed to be modified and thus rejected.

With reference to Figure 4, an exemplary method of extracting the source verifier data and the client verifier data from a video frame of a video content will now be described. The video frame consisting of pixels is partitioned into blocks of pixels, wherein the number of rows of the blocks, N, and the number of columns of the blocks, M, are predetermined or previously generated. The first block of the first column is set as an off-state and a summed pixel value of the block is obtained. Similarly, the summed pixel value of the subsequent block is obtained. An off-state is assigned to the block when the difference of the summed pixel values from the previous block is smaller than a threshold value, Δ, which is predetermined or generated previously. If it is determined otherwise, an on-state is assigned to the block. The off-state or on-state assignation is performed similarly for every block of every column of the video frame. The number of off-state obtained is then incorporated into an equation (a) to compute a variable, c. ο = Ν λ/(1+ λ) + Δ/ΝΜ (a)

wherein,

N= number of rows

M=number of columns

Δ= threshold value

λ= 1 /average no. of off-states Equation (a) can be rewritten in differential equation (b)

(i - c) ¾ = (N - i + 1)λ^__! - {(N - i) + i}Fi + (i + 1)F, Equation (b) in turn can be rewritten in matrix form (c)

dF(x)

D = F(x), x > 0

dx

where D= diag (-c, 1 -c, 2-c, N-c) and

A set of eigenvalues can then be obtained. The set of eigenvalues are obtained from each of the video frame in the video content and compiled to form a verifier data. Verifier data extracted from the main server (1 ) constitutes the source verifier data and verifier data extracted from the client (3) constitutes the client verifier data.

Although the present invention has been described in a specific embodiment as in the above description, it is understood that the above description does not limit the invention to the above given details. It will be apparent to those skilled in the art that various changes and modification may be made therein without departing from the principle of the invention or from the scope of the appended claims.

Claims

1 . A system (10) for authenticating a media content comprising:

a main server (1 ) for distributing the media content; and

at least a client (3) connected to the main server (1 ) for receiving the media content, characterized in that the system further comprising:

a verifier generator (4) operating with the main server (1 ) for generating key parameter values to extract source verifier data from the media content, wherein the generated key parameter values and source verifier data are sent to the client (3) for authenticating the media content; and

a verifier extractor (5) operating with the client (3) for extracting client verifier data from the received media content based on the key parameter values generated by the verifier generator (4), wherein the client verifier data are compared with the source verifier data received from the main server (1 ) for determining the authenticity of the media content.

2. A system (10) for authenticating a media content according to Claim 1 , wherein the main server (1 ) and the client (3) are connected to at least a sub-server (2) via a secured communication channel for transmitting the media content from the main server (1 ) to the client (3) in any event that the main server (1 ) directs the sub-server (2) for transmission.

3. A system (10) for authenticating a media content according to Claim 1 , wherein the media content is a video content.

4. A method for authenticating a media content distributed from a main server (1 ) to a client (3), in accordance to the system (10) as claimed in Claim 1 , characterized by the steps of:

providing the media content to the main server (1 );

generating key parameter values and extracting a source verifier data from the media content based on the key parameter values generated by a verifier generator (4) at the main server (1 ); sending the key parameter values and the source verifier data to the client (3);

transmitting the media content to the client (3);

extracting a client verifier data from the media content based on the received key parameter values when the media content is received by the client (3);

determining the authenticity of the media content by comparing the source verifier data and the client verifier data, wherein the media content is deemed modified when the client verifier data does not match the source verifier data.

5. A method for authenticating a media content according to Claim 4, wherein the media content is a video content comprising a threshold value and a plurality of video frames, each frame with a plurality of pixels grouped in rows and columns.

6. A method for authenticating a media content according to Claim 5, wherein the threshold value, the rows, and the columns are the key parameter values.

7. A method for authenticating a media content according to Claim 6, wherein the key parameter values are predetermined by the main server (1 ).

8. A method for authenticating a media content according to Claims 4, wherein extracting the source verifier data and the client verifier data comprising the steps of:

partitioning a video frame of a video content into blocks in rows and columns;

setting an initial block in a first column as an off-state and summing the pixel values in the block;

summing the pixel values of every subsequent block for every row; setting either off-state or on-state for every subsequent block by comparing the summed pixel values to that of the previous block, wherein off-state is assigned when the difference from the previous is smaller than a threshold value;

calculating number of off-states in the video frame;

generating verifier data based on the number of off-states in the video frame.

9. A method for authenticating a media content according to Claim 8, wherein the source verifier data and the client verifier data are represented in set of eigenvalues arranged in ascending order.

10. A method for authenticating a media content according to Claim 9, wherein the set of eigenvalues are computed from a differential equation based on the number of off-states in the video frame.