WO2015143027A1

WO2015143027A1 - Bandwidth-based encryption for multimedia content

Info

Publication number: WO2015143027A1
Application number: PCT/US2015/021231
Authority: WO
Inventors: Stephane Haziza
Original assignee: Thomson Licensing
Priority date: 2014-03-21
Filing date: 2015-03-18
Publication date: 2015-09-24

Abstract

Decryption processing for multimedia content is reduced by changing encryption techniques based on bandwidth. Bandwidth thresholds, if any, are selected to determine what type of encryption and/or a frequency of packet encryption is required. Bandwidth is then monitored during an encoding process and the encryption is augmented based on the bandwidth. The intensity and/or frequency of the encryption is typically reduced during high bandwidth times.

Description

BANDWIDTH-BASED ENCRYPTION FOR MULTIMEDIA CONTENT

BACKGROUND

[0001] Movie studios tend to transmit copies of their production work digitally.

However, to securely transmit cinema-quality content e.g., high-definition native (1080i,

1080p, 4K, etc.), long encryption keys and complex algorithms are typically needed. Powerful processors are then required at the receiving end of the content to decrypt it. Oftentimes, when the receiving processor is not able to keep up with the heavy decryption workload, the outgoing content can become stuttered due to the processor running near its maximum capacity. Upgrading the processors sometimes requires the entire content receiver to be replaced, a costly endeavor. A solution is needed to allow large content providers, like movie studios, to securely transmit their content without deteriorating the user experience and without requiring the end user equipment to be upgraded. SUMMARY

[0002] Reduction of processing power is provided for multimedia processors that are required to use more and more processing power for cryptographic algorithms in the multimedia audio/video data technologies. These reduction techniques can be implemented either in hardware and/or software using intelligent driver layers involving signalization from a head-end or a back-end that is issuing the content. The techniques are based on digital packetized streams, such as MPEG / DSS / TCP-IP/ RTP/ RTSP etc. which can be manipulated at a packet size level, and have the capability to decrypt contents depending on encoding bandwidth level. For example, if a content provider sends a movie in high definition 1080p with an average of lOMb/s, it doesn't have a permanent high bandwidth to sustain for the duration of the movie transmission. Therefore, depending on a threshold that is defined in real-time by a back-end or a head-end, the level of encryption and type of encryption changes during the transmission of the content, relieving some of the decryption duties of the receiving processor.

[0003] The above presents a simplified summary of the subject matter in order to provide a basic understanding of some aspects of subject matter embodiments. This summary is not an extensive overview of the subject matter. It is not intended to identify key/critical elements of the embodiments or to delineate the scope of the subject matter. Its sole purpose is to present some concepts of the subject matter in a simplified form as a prelude to the more detailed description that is presented later.

[0004] To the accomplishment of the foregoing and related ends, certain illustrative aspects of embodiments are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the subject matter can be employed, and the subject matter is intended to include all such aspects and their equivalents. Other advantages and novel features of the subject matter can become apparent from the following detailed description when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is an example a multimedia content delivery system illustrating an an exemplary embodiment for practicing the present principles.

[0006] FIG. 2 is a chart showing the encoding bandwidth over time for multimedia content.

[0007] FIG. 3 is a method of implementing bandwidth based encryption for the exemplary embodiment of FIG. 1.

DETAILED DESCRIPTION

[0008] The subject matter is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the subject matter. It can be evident, however, that subject matter embodiments can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the embodiments.

[0009] Multimedia content processing bottlenecks are dramatically reduced by implementing the "Encoding On Demand" based system of the present principles while using low cost embedded processors despite the huge processing requirements for video technologies such as high definition (HD - 1080p) and ultra-high definition (UHD - 4K) video along with studio security requirements. The advantage of the encoding technique of the present principles is that there will be no need to add hardware or make a modification to a specific algorithm already in use in a multimedia decryption system.

[0010] As illustrated in a system 100 of FIG. 1, a head-end and/or back-end unit

102 populates the "signalization" 106 present in on-going streaming content, either from pre-fetch or real time (Program Specific Information (PSI) table for Moving Picture

Experts Group (MPEG) /Digital Satellite System (DSS), additional Internet Protocol (IP) package "preamble"). This is the synchronization between the back-end/head-end unit 102 and a receiving/playing multimedia device 104 (e.g., set top box (STB), personal computer (PC), mobile device, etc.). It can also be embedded in a file using a Digital Rights Management (DRM) delivered key. In this example, the multimedia device 104 has a decryption engine 112, a processor 114, a decompression engine 116 and a signalization engine 118.

[0011] The head-end/back-end unit 102 controls the amount and type of encryption for content delivery to the multimedia device 104. The multimedia device 104 continues to operate normally. Its processor workload is reduced automatically due to the fact that the amount and type of encryption is altered at the head-end/back-end unit 102 in accordance with the present principles. Thus, the processor within the multimedia device 104 has a reduced workload when the back-end/head-end unit 102 reduces the amount and/or type of encryption.

[0012] The back-end/head-unit 102 can contain a bandwidth monitor 108 and an encoder 110. The bandwidth monitor 108 tracks the encoding bandwidth for a given multimedia content. The bandwidth monitor 108 can be used to trigger thresholds that have been previously set. These thresholds enable the encoder 110 to encrypt the multimedia content based on various types of encryption and/or frequency of encryption. The encoder 110 can also vary the encryption type and/or frequency based on the bandwidth alone. It is also possible for the encoder 110 to obtain knowledge of the receiving device's decryption bandwidth capabilities. This information can also be used to appropriately encrypt the multimedia content so that it lessens the burden on the receiving device's decryption processor.

[0013] A simple approach to understanding the implementations of the techniques is to have a system packet-based (e.g., MPEG or IP) that only encrypts every other packet or only encrypts every one to four packets (e.g., every second packet is encrypted, or every third packet is encrypted, or every fourth packet is encrypted, etc.). One skilled in the art can appreciate that the packet encryption selection frequency can vary as well. Thus, for example, every second packet can be encrypted during low bandwidth demand and every fourth packet encrypted during higher bandwidth demand.

[0014] These techniques can, for example, reduce the processor or Digital Signal

Processor (DSP) to almost 50% of its needed resources for decryption. This enables the processor to properly execute an ongoing codec decompression instead of heavy decryption algorithms. These techniques can be applied to micro-code inside a DSP, a transputer and/or a processor and the like. It can also be applied to hardware made to execute decryption. Thus, it has the advantage to be generic to any encryption algorithm. This satisfies the need of a movie studio, since the content sitting in a protected content store is still not clearly viewable even though only part of it is encrypted.

[0015] The particularity of the Encoding On Demand technique of the present principles is based on the almost instant bandwidth changes as shown in a graph 200 of FIG. 2. This illustrates a typical encoding (compression) of video/audio during content encoding. A constant bandwidth does not exist for encoding the full content (e.g., more still pictures, more detailed area etc.). A threshold can be arbitrarily set where the content is encrypted or not, or with weaker algorithm(s) if necessary. The head-end or back-end 102 can use either MPEG/DSS signalization to determine when to start and stop such threshold. In addition, more than one criteria can be used as shown in TABLE 1

TABLE 1 where the bandwidth_threshold is the value of the algorithm and changes based on 16 bit encoding. TABLE 2 illustrates an example of an applied algorithm.

TABLE 2

[0016] For example, a System Target Decoder is assumed to have zero (or known) delay in a decoder block, and an encoder and transmission path are also assumed to have zero delay, that is, buffers represent the only system delay. Zero-delay elements can also have a constant delay without disturbing the operation. The decoder is synchronized with the encoder by time stamps, which are introduced in the following way (e.g., MPEG ISO 13818 based system). * The encoder contains a master oscillator and counter, called the System Time Clock

(STC).

A constant quantity equal to the sum of the encoder and decoder buffer delays is added, creating a Presentation Time Stamp (PTS), which is then inserted in the first of the packet(s) representing that picture or audio block.

Entered into the bitstream under certain conditions is a Decode Time Stamp (DTS), which represents the time at which the data should be taken instantaneously from the decoder buffer and decoded. Since the System Target Decoder delay is zero, the DTS and PTS are identical except in the case of picture reordering for B pictures. The DTS is only used where it is needed because of reordering. Whenever DTS is used, PTS is also coded. PTS (or DTS) is entered in the bitstream at intervals.

Output of the encoder buffer is time stamped with System Time Clock (STC) values, called Program Clock Reference (PCR) if the stamp is at the transport packet level, or System Clock Reference (SCR) at the Packetized Elementary Stream (PES) level (e.g., lOOmS intervals).

[0017] The Encoding On Demand technique of the present principles can be easily migrated to any other content protection system type DRM with hypertext markup language (HTML) type preamble indicating the needed information in a file, as well as the time stamp to start and stop the type decryption. With this system, it can be appreciated to use a light algorithm with high bandwidth encoding.

[0018] In view of the exemplary systems shown and described above,

methodologies that can be implemented in accordance with the embodiments will be better appreciated with reference to the flow chart of FIG. 3. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of blocks, it is to be understood and appreciated that the embodiments are not limited by the order of the blocks, as some blocks can, in accordance with an embodiment, occur in different orders and/or concurrently with other blocks from that shown and described herein. Moreover, not all illustrated blocks may be required to implement the methodologies in accordance with the embodiments.

[0019] FIG. 3 is a flow diagram of a method 300 of encrypting multimedia content based on encoding bandwidth in accordance with the present priciples. Thresholds, if any, are first determined for the type of encryption and/or the frequency of packet encryption 302. The types of encryption can be, for example, classified according to the amount of their processor usage. Therefore, a "light" or "simple" encryption algorithm would have less processor usage than a "heavy" or "complex" encryption algorithm. Thus, thresholds could be determined based upon the encoding bandwidth at any given time to trigger usage of a light or heavy encryption algorithm. Likewise, thresholds can be established for the frequency of the packet encryption (e.g., every other packet, every third packet, etc.). As stated previously, the frequency of the packet encryption can also be varied with the bandwidth as opposed to stopping and starting a given frequency. Thus, for example, the threshold can be used to go from every other packet to every fourth packet to alter the required decryption processing.

[0020] The multimedia content processing bandwidth can be monitored in real- time to facilitate implementation of the encryption type and frequency 304. Encryption techniques are then applied to the multimedia content based on the bandwidth and/or thresholds 306. Since the thresholds are not required, the encryption can be based solely on the bandwidth. The monitoring 304 and encryption application 306 continue for the duration of the multimedia content encoding. One skilled in the art can appreciate the amount of encryption is directly related to the required amount of decryption. Thus, it is also possible to apply the above method with the knowledge of the decryption processing bandwidth of a receiving device. Therefore, the above method can be augmented to be based on the bandwidth of the receiving device rather than based on the encoding bandwidth.

[0021] When provided by a processor, the functions can be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which can be shared. Moreover, explicit use of the term "processor" or "controller" should not be construed to refer exclusively to hardware capable of executing software, and can implicitly include, without limitation, digital signal processor ("DSP") hardware, read-only memory ("ROM") for storing software, random access memory ("RAM"), and non- volatile storage. Moreover, all statements herein reciting instances and embodiments of the invention are intended to encompass both structural and functional equivalents. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure).

[0022] What has been described above includes examples of the embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the embodiments, but one of ordinary skill in the art can recognize that many further combinations and permutations of the embodiments are possible. Accordingly, the subject matter is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim.

Claims

1. A method for encrypting multimedia content, comprising:

monitoring multimedia content bandwidth; and

applying encryption during encoding of the multimedia content based on the multimedia content bandwidth.

2. The method of claim 1, further comprising:

determining at least one bandwidth threshold for applying at least one type of encryption to the multimedia content; and

applying the at least one encryption type during the encoding of the multimedia content based, in part, on the at least one threshold.

3. The method of claim 1, further comprising:

determining at least one bandwidth threshold for applying at least one frequency of multimedia content packet encryption; and

applying encryption to the encoding of the multimedia content based, in part, on the at least one threshold.

4. The method of claim 3, wherein the at least one encryption frequency is at least one of every second packet, every third packet or every fourth packet.

5. The method of claim 1, further comprising:

obtaining a decryption bandwidth capability from a multimedia device that plays multimedia content; and

applying encryption during the encoding of the multimedia content based on the multimedia content encoding and decryption bandwidths.

6. A system that encrypts multimedia content, comprising:

a bandwidth monitor that monitors multimedia content bandwidth; and an encoder that applies encryption during encoding of the multimedia content based on the multimedia content bandwidth provided by the monitor.

7. The system of claim 6, wherein the encoder determines at least one bandwidth threshold for applying at least one type of encryption to the multimedia content and applies the at least one encryption type during encoding of the multimedia content based, in part, on the at least one threshold.

8. The system of claim 6, wherein the encoder determines at least one bandwidth threshold for applying at least one frequency of multimedia content packet encryption and applies encryption during encoding of the multimedia content based, in part, on the at least one threshold.

9. The method of claim 8, wherein the at least one encryption frequency is at least one of every second packet, every third packet or every fourth packet.

10. The method of claim 61, wherein the encoder obtains a decryption bandwidth capability from a multimedia device that plays multimedia content and applies encryption to the encoding of the multimedia content based on the multimedia content encoding and decryption bandwidths.

11. A system that encrypts multimedia content comprising:

a means for monitoring multimedia content bandwidth; and

a means for applying encryption during encoding of the multimedia content based on the multimedia content bandwidth.

12. The system of claim 11, further comprising:

a means for determining at least one bandwidth threshold for applying at least type of encryption to the multimedia content; and

a means for applying the at least one encryption type to the encoding of the multimedia content based, in part, on the at least one threshold.

13. The system of claim 11, further comprising:

a means for determining at least one bandwidth threshold for applying at least one frequency of multimedia content packet encryption; and

a means for applying encryption during encoding of the multimedia content based, in part, on the at least one threshold.