Key based decipher including its generation, distribution and usage

A decipher key based decipher with at least a portion of the decipher key dissolved into the decipher is disclosed. The decipher includes in-line instructions specifically designed to incrementally contribute to computation of Me Mod n, where e is a predetermined at least partially unique decipher key. In one embodiment, the decipher includes a first in-line instruction to set an output variable to equal to 1, and a second in-line instruction to set the output variable to equal to the square of the output variable modulus n. In another embodiment, the decipher includes in-line instructions that perform the incremental computation in accordance with an addition chain of e.

FIELD OF THE INVENTION

The present invention relates to the field of secure content distribution and consumption. More specifically, the present invention is related to a key based decipher, including its generation, distribution and employment in secure consumption of content.

BACKGROUND OF THE INVENTION

Advances in microprocessor, networking and related technologies have led to wide spread deployment and adoption of server-client based applications. In particular, with the advance of high speed public networks, such as the Internet, increasing amounts of rich content are being served and available for consumption by networked clients. Much of these rich contents are streamed in digital form to the client devices for consumption.

Unlike analog copies of the earlier era, the quality of each digital copy is as good as the original/master copy. As the processing capabilities of the client devices and the ease of exchanging data between a large number of geographically dispersed client devices continually to increase, the issue of protecting these rich content from misappropriation, i.e. unauthorized copying and/or re-distribution, has become increasingly important.

Resultantly, a large body of security techniques, including ciphering and deciphering techniques, have been developed, and employed in content distribution and consumption to protect the content from misappropriation. Among them are key based techniques, in particular, public key and private key techniques that involve modulus computations.

An example of one, such technique is the Rivest, Shamir and Adleman (RSA) public key and private key technique. Briefly, the RSA technique works as follows:1. Two large prime numbers, p and q, are first generated;2. A number n is set to pq;3. A number m is set to (p−1)(q−1);4. Next, a small number e, coprime to m, is chosen;5. Then, d where de % m=1 is determined;6. e and n, often referred to as the public key, are published;7. d and n, often referred to as the private key, are kept secret;8. Portions of content are corresponding encoded as Ms;9. Each M is encrypted into a corresponding C by computing Me% n;10. Each C is decrypted back into M by computing Cd% n;where x % y means the remainder of x divided by y.

In other words, the effectiveness of security techniques, such as RSA, are substantially dependent on keeping the private key, d and n in the case of RSA, secret. Unfortunately, the responsibility is often that of the client devices, which in general, are not considered to be sufficiently secured.

Various techniques to obfuscate and/or hide the keys are known and employed. Unfortunately, the robust techniques are often too complex to implement, and the relatively easy to implement ones are not robust enough.

Thus, a need exists to improve the security of public key and private key techniques, in particular, a need exists to more efficiently keeping the private key from being learned.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention includes a key based decipher component of a content player, and associated methods of operations to generate, distribute and use the key based decipher for secure content provision and consumption.

In the following description, various aspects of the present invention will be described. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some or all aspects of the present invention. For purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the present invention.

Terminology

Parts of the description will be presented in content streaming and security terminology consistent with the manner commonly employed by those skilled in the arts to convey the substance of their work to others skilled in the respective arts. In particular, in a server/client device, content, player and associated data may take the form of electrical, magnetic, or optical signals capable of being stored, transferred, combined, and otherwise manipulated through electrical and/or optical components of a processor, and its subsystems.

Section Headings, Order of Descriptions and Embodiments

Section headings are merely employed to improve readability, and they are not to be construed to restrict or narrow the present invention.

Various operations will be described as multiple discrete steps in turn, in a manner that is most helpful in understanding the present invention, however, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

Overview

FIG. 1illustrates an overview of a content provision and consumption environment, having a number of server and client devices, where selected ones of the server and client devices are incorporated with the teachings of the present invention, in accordance with one embodiment. As illustrated, for the embodiment, content provision and consumption environment100includes client devices or simply clients112, content player distribution server122, content server132and production server142, coupled to each other as shown, i.e. via networks110.

Production server142performs the function of building content player126, and encoded content136, and providing them to e.g. player distribution server122and content server132respectively. For the embodiment, production server142may include player builder144, key based decipher generator146, decoder148, content generator150and content152. Content generator150in turn may include encoder154.

Player builder144performs the function of building content player126for distribution by distribution server122. More specifically, player builder144performs the function by invoking key based decipher generator146to generate key based decipher128, and combining the generated key based decipher128with a decipher key, if applicable, and decoder148to form content player126. During operation, i.e. when content player126is used by a client112to request and consume encoded content136, key based decipher128is employed to decipher access control information provided by content server132to access encoded content136of interest, to ensure content player126is a legitimate, i.e. properly licensed content player126.

The exact nature of the access control information and the process of ensuring content player126is a legitimate or properly licensed content player, beyond the fact that deciphering of ciphered information is involved, is non-essential to the practice of the present invention. The access control information and the process may be any one of access control information and/or processes currently being practiced or to be designed.

Similarly, except for key based decipher128, including its generator146, and the fact that content player126includes key based decipher128and possibly, a decipher key, player builder144including decoder148may be any one of a number of these elements known in the art or to be designed.

Key base decipher128, including its generation, and the inclusion of a decipher key will be further described below, after the overview description has been given for other elements illustrated inFIG. 1.

Content generator150, on the other hand, performs the function of generating encoded content136for distribution by content server132, using encoder154to encode content152. Content generator150, including encoder154may be any one of a number of these elements known in the art or to be designed.

Continuing to refer toFIG. 1, distribution server122performs the function of distributing content player126to requesting clients112, which in turn may use the received content player126to request, receive and consume content136provided by content server132. In other words, clients112and content server132perform the functions of requesting/consuming and providing content respectively.

For the embodiment, content server132may include content distributor134. Clients112and content server132, including content distributor134, may be any one of a number of these devices known in the art or to be designed. For example, in the case of client112, it may be a hand held palm-sized computing device, such as a mobile phone or pocket PC, a tablet computing device, a laptop computing device, a desktop computing device, a set-top box, and so forth. In the case of server132, it may be an entry level, a mid-size or an array of high power servers. Further, the requested, provided and consumed content may be of any one of a number of types and/or forms, including but are not limited to audio, video, text, graphics, and so forth, or combinations thereof.

In addition to content player126, distribution server122may be equipped with distributor124, which performs the function of distributing content player126to a client112on request. Distributor124may distribute content player126with or without qualification, authentication and payment of fees. The distribution may also be performed in accordance with any protocol, format and/or speed. In other words, in general, distributor124may be any one of a number of distributors known in the art or to be designed.

As described earlier, content player126includes key based decipher128of the present invention, and optionally a decipher key and decoder148. Upon installation or set up on a client112, content player126performs for the client112, the function of requesting and rendering content, which may include using decipher128in the validation process and/or decoder148to decode encoded content.

As will be described in more detail below, the enclosed decipher key may at most be used partially only. In other words, the decipher key may be included with content player126partly to obfuscate or confuse a party attempting to misappropriate content.

Key based decipher128performs the function of deciphering access control information with an unconventional, i.e. novel, design. As will be described in more detail below, key based decipher128is at least partially decipher key specific, with a portion of the decipher key being “dissolved” into decipher128.

The term “dissolved” or “dissolution” as used herein refers to the fact that decipher128is hard “coded” or “wired” to decipher only ciphered content designed to be deciphered with decipher keys having the hard coded/wired portion. The situation is analogous to the dissolution of powder in a liquid. Upon dissolving the powder into the liquid, the existence of the powder may be inferred only from the characteristics of the liquid, but not observable in its natural state. For example, when sugar is dissolved in water, the presence of the sugar can only be inferred from the sweetness of the water, but not observable in its natural powder state. Similarly, the portion of the decipher key may only be inferred from the structure of decipher128but unobservable as an entity in its natural state (i.e. a binary number).

Accordingly, during operation, decipher128needs only be provided with the not “dissolved” portion of the decipher key. Thus, arbitrary values may be provided for the “dissolved” portion to obfuscate or confuse a party attempting to misappropriate the content. In the case where the entire decipher key is “dissolved” into decipher128, arbitrary values for the entire “decipher key” may be provided to decipher128during operation to obfuscate and/or misdirect. However, such obfuscation is optional.

Resultantly, decipher128may not decipher ciphered access control information correctly if the access control information is not ciphered in a manner to be deciphered with a decipher key having the hard coded/wired portion. However, this seemingly more limiting in capability is abundantly compensated with the reduced need to obfuscate or hide the decipher key, when content player126is provided to a client112for use to consume content provided e.g. by content server132. Further, a partially or entirely phony decipher key may be provided to obfuscate and/or misdirect. Thus, the counter intuitive approach actually results in an unexpected improvement in protecting content from misappropriation.

For the purpose of this application, hard coded/wired “instructions” may also be referred to as in-line “instructions”.

Decoder148performs the function of decoding encoded content. Decoder148may be equipped to decode content encoded in accordance with one or more encoding approach/standard. For example, decoder148may be equipped to decode content encoded in accordance with the MPEG3 and/or MPEG4 standard (MPEG=Motion Picture Experts Group). In other words, in general, decoder148may be any one of a number of decoders known in the art or to be designed.

Still referring toFIG. 1, network110may be any one of one or more public and/or private local, regional and/or wide area networks known in the art or to be designed.

Before further describing the present invention, and the various elements ofFIG. 1, it should be noted that in alternate embodiments, the present invention may be practiced with one or more functions of distribution server122, content server132and production server142to be further distributed among additional servers. Similarly, the present invention may be practiced with one or more of servers122,132and142combined instead. Likewise, encoded content136may also be ciphered, and key based decipher128of the present invention may also be used to decipher the ciphered encoded content136.

Content Player/Content Building Including Key Based Decipher Generation

FIGS. 2a-2cillustrate the operational flow of the relevant aspects of production server142, including content player building, in particular, key based decipher generation, and content building, in accordance with one embodiment each.

As illustrated inFIG. 2a, during operation, production server142receives a request to build (and provide) content player126and/or encoded content136, block202. The request may be submitted in any one of a number of manners, including but are not limited to submission from a scheduled job, an operator of production server142, player distribution server122, content server132and so forth. In response, if the request is for building content player126, production server142invokes content player builder144to build content player126, and if applicable, provide built/re-built content player126to distribution server122, block204. In particular, content player builder144invokes key based decipher generator146to generate key based decipher128.

Referring now toFIG. 2b, during operation, content player builder144is provided with the length of the decipher key and the specified portion, on which the key based decipher128to be specifically generated for, block212. In one embodiment, as described earlier, the specified “portion” may be the entire decipher key.

On receipt, content player builder144invokes key based decipher generator146to generate key based decipher128that is hard coded/wired specifically for the decipher key (having the specified portion), block214.

On generation of key based decipher128, content player builder144combines at least the generated key based decipher128with the decipher key, if applicable, and decoder148to form content player126, block216. As described earlier, arbitrary values may be provided for the “dissolved” portion of the decipher key to obfuscate and/or redirect. Further, other tamper resistant treatments may be applied to decipher128and/or other components of content player126to further strengthen content protection.

Referring now toFIG. 2c, on invocation, key based decipher generator146first generates an instruction to set the output variable (C) to “1”, block222. Then for the specified portion of the decipher key, key based decipher generator146selects a next bit, block224. Key based decipher generator146generates an in-line instruction to set the output variable (C) to its own square modulus n, i.e. C=C*C mod n, block226. Next, key based decipher generator146conditionally generates an in-line instruction to set the output variable (C) to the product of the output variable (C) and an input variable (M) to be deciphered modulus n, i.e. C=C*M mod n, if the selected bit is a “1” bit, block228.

Next, key based decipher generator146determines whether there are more specified bits requiring corresponding hard code to be generated, block230. If there are, key based decipher generator146returns to block224and continues the generation process from there. Else, key based decipher generator146terminates the generation process.

For embodiments where key based decipher generator146is hard coded for only a portion of a decipher key, e.g. xxxx0101, where xxxx is the non-specified portion, and 0101 is the specified portion, the key based decipher generation process further includes generating for the key based decipher128a sub-program/module with instructions to computea) C=C*C Mod n; andb) C=C*M Mod n if the current bit=1

For the above described example, where the decipher key is 8-bit long, and only the last 4 bits are specified, e.g. xxxx0101, the key based decipher128comprises the following in-line instructionsa) C=1b) For j=1 thru 4c) C=C*C Mod n;d) C=C*M Mod n if bit(j)=1e) C=C*C Mod n;f) C=C*C Mod n;g) C=C*M Mod n;h) C=C*C Mod n;i) C=C*C Mod n; andj) C=C*M Mod n

Any one of a number of programming languages may be employed to practice the present invention. That is, the above mentioned “in-line instructions” may be expressed in the syntax of any one of a number of programming languages known in the art or to be designed. Note that even for hard wired embodiments, generator146may generate key based decipher128in an intermediate form using one of a number of known or to be designed hardware design language, such as Verilog.

Those skilled in the art will appreciate that in the above examples, the decipher key is purposely kept short for ease of presenting and understanding the invention. In practice, the decipher key is typically significant longer than the 8 bit versions illustrated above. Nevertheless, one skilled in the art will be able to practice the present invention from the foregoing and description to follow. The present invention may be practiced with various embodiments for various deciphering keys with various specified portions, including fully specified deciphering keys.

Referring back toFIG. 2a, block204, if the request is for building ciphered as well as encoded content136, production server142invokes content generator150to generate ciphered as well as encoded content136, and if applicable, provides the built/re-built content136to content server132. In particular, content generator150invokes encoder154to encode content152.

Alternate embodiment of Key Based Decipher Generator

FIG. 5illustrates an alternate embodiment of key based decipher generator146for generating key based decipher128that is hard coded/wired specifically for a decipher key. The embodiment is based on computing the quantity Me, using an addition chain of e, the decipher key. An addition chain of e is a sequence of termsa0, a1, a2, . . . ar

with a0=1 and ar=e, and that the sequence is constructed in such a way, for all k, there exists i, j<k, whereak=ai+aj

r is referred to as the length of the addition chain, and i may equal j.

The quantity Memay be computed by following the addition chain of e. That is, by first computing M1, then proceeds to successively compute a number of M to the power ak, based on two preceding terms of M to the power aiand M to the power aj, where aiand ajare members of the addition chain of e, until M to the power ak, i.e. Me, is reached.

Note that for each e, there may be more than one addition chain. Preferably, the shortest one is employed, however, not necessarily.

An addition chain for an integer e may be determined using any one of a number of techniques known in the art.

Accordingly, at block502, on receipt of a decipher key e, key based decipher generator146first selects an addition chain of e. Next, at block504, key based decipher generator146generates a first in-line instruction to compute a first intermediate result based on the first term of the selected addition chain of e. Then, at block506, key based decipher generator146generates another in-line instruction to compute a next intermediate result based on the next term of the selected addition chain of e, using two preceding computed intermediate results.

At block508, key based decipher generator146determines if further computation still needed. That is, whether Mehas been reached when the most recent intermediate result is computed. If further computation is needed (i.e. Mehas not been reached), the process returns to block506; else the process continues at block510, where an in-line instruction is generated to compute MeMod n.

In other words, viewing the embodiment ofFIG. 2candFIG. 5together, key based decipher generator146successively generates a number of in-line instructions to incrementally contribute to the computation of the MeMod n. The incremental contributions may be effectuated through a variety of equivalent computation techniques.

Client, Player Distribution Server and Content Server

FIGS. 3a-3cillustrate the operational flow of the relevant aspects of client112, content player distribution server122and content server132respective, in accordance with one embodiment each.

As illustrated inFIG. 3a, during operation, client112requests distribution server122for, and receives content player126, including key based decipher128and decoder148, block302. Further, at another point in time during operation, client112requests content server132for, and receives encoded content136(after verification of the legitimacy of content player126using key based decipher128), block304. In response, content player126using decoder148, decodes the encoded content, block306. Further, content player126renders the recovered, i.e. decoded, content.

As illustrated inFIG. 3b,during operation, on receipt of a request for content player126, block322, distribution server122(upon satisfying itself with the qualification of the requestor, if applicable, e.g. through tender payment of the proper fees) provides content player126to the requesting client112, including key based decipher128and decoder148, block324.

Similarly, as illustrated inFIG. 3c, during operation, on receipt of a request for content, block332, content server132first verifies the legitimacy of the requesting content player126, block334. As described earlier, while the verification process may be effectuated in any one of a number of known or to be designed manners, the present invention assumes at least deciphering of certain ciphered access control information are involved as part of the process. On verification, distribution server122provides encoded content player126to the requesting client112, block334.

Example Computer System

FIG. 4illustrates one embodiment of an exemplary digital system suitable for use to practice the present invention, either as a client system or a server system. As a client system, digital system400may be a desktop computer system, a laptop computer system, a palm sized computing device, a wireless mobile phone, a set-top box, an Internet appliance and the like. As a server, digital system400may a single or a cluster of computer systems.

As shown, exemplary digital system400includes one or more processors402and system memory404. Additionally, system400includes mass storage devices406(such as diskette, hard drive, CDROM and so forth), input/output devices408(such as keyboard, cursor control and so forth) and communication interfaces410(such as network interface cards, modems and so forth). The elements are coupled to each other via system bus412, which represents one or more buses. In the case of multiple buses, the buses are bridged by one or more bus bridges (not shown). Each of these elements performs its conventional functions known in the art. In particular, system memory404and mass storage406are employed to store a working copy and a permanent copy of the programming instructions implementing the teachings of the present invention, i.e. key based decipher generator146, and so forth. The permanent copy of the programming instructions may be loaded into mass storage406in the factory, or in the field, as described earlier, through a distribution medium (not shown) or through communication interface410(from a distribution server (not shown). The constitution of these elements402-412are known, and accordingly will not be further described.

Conclusion and Epilogue

Thus, it can be seen from the above descriptions, an improved key based decipher, including its generation and usage for content consumption have been described.

While the present invention has been described in terms of the foregoing embodiments and example applications, those skilled in the art will recognize that the invention is not limited to the embodiments and example application described. The present invention can be practiced with modification and alteration within the spirit and scope of the appended claims.

Thus, the description is to be regarded as illustrative instead of restrictive on the present invention.