Challenge-response method and associated client device

• US 9,787,479 B2
• Filed: 03/27/2013
• Issued: 10/10/2017
• Est. Priority Date: 03/27/2013
• Status: Active Grant

• Current Assignee: Irdeto B.V. (MultiChoice Group Ltd.)
• Original Assignee: Irdeto B.V. (MultiChoice Group Ltd.)
• Inventors: Wajs, Andrew Augustine, Ciordas, Calin, Zhang, Fan
• Primary Examiner(s): Chang, Kenneth
• Application Number:
  US14/778,860
• Publication Number:
  US 20160043872A1
• Time in Patent Office: 1,658 Days
• CPC Class Codes: H04L 2209/24 Key scheduling, i.e. generating round keys or sub-keys for block encryption
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 2209/603 Digital right managament [DRM]
• CPC Class Codes: H04L 9/0816 Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
• CPC Class Codes: H04L 9/3271 using challenge-response

Abstract

There is described a challenge-response method for a client device. The method comprises steps of: (a) receiving challenge data, wherein the challenge data is content encrypted using an encryption key, the content including a nonce; (b) using a secured module of the client device to access the content by decrypting the challenge data using a decryption key of the secured module, the decryption key corresponding to the encryption key; (c) processing a version of the content output by the secured module so as to obtain the nonce; and (d) providing the nonce as a response. There is also described a client device for implementing the above challenge-response method. There is also described a computer program which, when executed by a processor, causes the processor to carry out the above challenge-response method. Finally, there is described a computer readable medium storing the above-mentioned computer program.

Claims

1. A challenge-response method for a client device, the method implemented by one or more processors, the method comprising steps of:

receiving challenge data, wherein the challenge data is audio content encrypted using an encryption key, the audio content including a nonce;

using a secured module of the client device to access the audio content by decrypting the challenge data using a decryption key of the secured module, the decryption key corresponding to the encryption key;

using the secured module to output an audible version of the audio content via a speaker of the client device;

receiving the audible version of the audio content using a microphone of the client device;

processing the audible version of the audio content received by the microphone so as to obtain the nonce; and

providing the nonce as a response.

2. The challenge-response method of claim 1 wherein the nonce is encoded with an error correcting code, and the processing step further comprises decoding the error correction encoded nonce.

3. The challenge-response method claim 1 wherein the nonce is included in the audio content as a digital watermark.

4. The challenge-response method of any one of claim 1 wherein the nonce is included in the audio content using a modulation encoding technique.

5. The challenge-response method of 1 claim wherein the decryption key is unique to the secured module.

6. A client device comprising one or more processors for implementing a challenge-response method, the client device comprising:

an input module for receiving challenge data, wherein the challenge data is audio content encrypted using an encryption key, the audio content including a nonce;

a secured module arranged to access the audio content by decrypting the challenge data using a decryption key of the secured module, the decryption key corresponding to the encryption key;

a speaker arranged to provide an audible version of the audio content output by the secured module; and

a microphone arranged to receive the audible version of the audio content;

a processor arranged to process the audible version of the audio content received by the microphone so as to obtain the nonce; and

an output module arranged to provide the nonce as a response.

7. The client device of claim 6 wherein the nonce is encoded with an error correcting code, and wherein the processor comprises an error correction module arranged to decode the error correction encoded nonce.

8. The client device of claim 6 wherein the input module forms part of the secured module such that the secured module is itself operable to receive the challenge data.

9. One or more tangible and non-transitory computer readable media comprising computer program code which, when executed by a processor, causes the processor to carry out a challenge-response method for a client device, by:

receiving challenge data, wherein the challenge data is audio content encrypted using an encryption key, the audio content including a nonce;

using a secured module of the client device to access the audio content by decrypting the challenge data using a decryption key of the secured module, the decryption key corresponding to the encryption key;

using the secured module to output an audible version of the audio content via a speaker of the client device;

receiving the audible version of the audio content using a microphone of the client device;

processing the audible version of the audio content received by the microphone so as to obtain the nonce; and

providing the nonce as a response.