International Business Machines Corporation

Sigfredo Ismael Nin

Jeffrey Bruce Lotspiech

Hongxia Jin

Dulce Beatriz Ponceleon

Dalit Naor

Florian Pestoni

Wilfred Edmund Plouffe, Jr

Robert Glenn Deen

Vladimir Zbarsky

Donald E Leake, Jr

Julian A Cerruti

Wilfred E Plouffe

Frank Andre Schaffa

Eric M Foster

Thomas Alexander Bellwood

Matthew Francis Rutkowski

James M Kasson

Duaine Wright Pryor, Jr

Ariel Virgil Mirles

A system, method, and computer program product to renewably prevent traitors in a broadcast encryption system from re-using compromised keys. A license agency assigns individual receivers a set of Sequence Keys preferably at manufacture, and assigns Sequence Key Blocks (SKBs) to protected content files to be distributed. The files may be distributed on prerecorded media and typically include several file modifications. The particular modifications in a pirated version of a file can help identify which traitors contributed to its theft. SKBs assigned to new files distributed after traitors have been identified cannot be usefully processed using the compromised keys employed in previous content piracy. Innocent receivers that happen to have compromised key(s) in common with traitors can use a replacement uncompromised Sequence Key from the set to usefully decrypt content. Traitors will however step through all their Sequence Keys without reaching one that will work.

Renewable traitor tracing

The present invention provides a method performed on a computer of preventing re-use of compromised keys in a broadcast encryption system. In an exemplary embodiment, the method includes (1) incorporating a particular set of Sequence Keys assigned by a license agency into individual receivers, (2) assigning a Sequence Key Block (SKB) by the license agency to at least one distributed protected file, (3) performing incremental cryptographic testing by the individual receivers to determine if a selected Sequence Key from the set of Sequence Keys is compromised, (4) if the selected Sequence Key is not compromised, decrypting the file, and (5) if the selected Sequence Key is compromised and if a subsequent Sequence Key from the set of Sequence Keys is available, selecting the subsequent Sequence Key.

Embodiments of the invention relate to digital content protection for recordable media using encryption and decryption based on device keys in the media. The invention increases the number of extended applications supported the media key blocks and facilitates the assignment of the applications to the media key blocks. One aspect of the invention concerns a method that comprises assigning a first media key block in a protected area of the media for extended applications accessing protected content, processing the first media key block with a first device key set to generate a first media key, and for each extended application, creating a second media key block in a protected area of the media. The second media key block is processed to generate a second media key. A content-accessing device processes the first and second media keys in order to access protected content.

Extending the number of applications for accessing protected content in a media using media key blocks

The present invention provides a method, system and program product for modifying content usage conditions during broadcast content distribution. Specifically, the present invention allows protected (e.g., encrypted, secured, etc.) content to be received along with content usage conditions, an encrypted combination of the content usage conditions and a title key (e.g., a MAC), and a key management block. Using the key management block, a key encrypting key can be determined for decrypting the combination. Once the combination is decrypted, the content usage conditions can be modified (e.g., edited, added to, etc.).

Method, system and program product for modifying content usage conditions during content distribution

Embodiments of the invention relate to obtaining forensic information for an anonymous attack of digital content without variations in a broadcast encryption system. In one embodiment a media device, being configured to record digital content on recordable media, receives digital content, a unified media key block, and a recording key table. The device calculates a set of recording keys from the recording key table using a media key variant from the unified media key block. The device then generates a title key and encrypts by the digital content in the generated title key. The device then encrypts the generated title key in each one of the calculated recording keys, adds a header including the encrypted titles keys to the encrypted digital content, and stores the encrypted digital content with the header on recordable media.

Recording keys in a broadcast-encryption-based system

According to one embodiment of the present invention, a system, method, and computer program product is provided for rebinding title keys in clusters of devices with distinct security levels in broadcast encryption systems. The method includes receiving a new management key and unbinding an encrypted title key with a previously used management key, the title key having a security class and residing in a title key block for a device having a security class, the device being in a cluster of devices including devices having a plurality of security classes. If the device security class is lower that the title key security class, the unbound title key is partially rebound with the new management key. the partially rebound title key is then saved in the title key block for the device.

Rebinding of content title keys in clusters of devices with distinct security levels

A system for protecting data in a security system generates and encodes a backup key for encoding long-lived secrets. The system generates a distribution plan for distributing cryptographic splits of the encoded backup key to selected persons based on geographic and organizational diversity. The distribution plan specifies a number M of the cryptographic splits to be generated and a number N of the cryptographic splits required to recover the backup key. The system processes utilize an init file comprising system parameters and state files each comprising parameters reflecting a state of the secure system after a transaction. Any of the state files may be used for any of the system processes. The state files and the init file are encoded by the backup key, thus protecting the long-lived secrets.

System and method for protecting data in a secure system

A trusted Java virtual machine provides a method for supporting tamper-resistant applications, ensuring the integrity of an application and its secrets such as keys. The trusted Java virtual machine verifies the integrity of the Java application, prevents debugging of the Java application, and allows the Java application to securely store and retrieve secrets. The trusted Java virtual machine environment comprises a TrustedDictionary, a TrustedBundle, an optional encryption method for encrypting and decrypting byte codes, and an underlying trusted Java virtual machine. The encrypted TrustedDictionary protects data while the TrustedBundle protects programming code, allowing applications to store secret data and secure counters. The application designer can restrict TrustedBundle access to only those interfaces that the application designer explicitly exports. The open source code may optionally be encrypted. Secrets required by the open source programming code of the application are encrypted in TrustedDictionary.

Tamper-resistant trusted Java virtual machine and method of using the same

A method for enforcing compliance in both the copy protect domain and service subscription domain for streamed multicast data. Each content is encrypted with a title key that itself is encrypted with a channel unique key which is a hash of a session key and a channel key. A compliant player is given the channel key upon registration for a subscription service (representing subscription protection) and is also given device keys upon activation (representing copy protection) for decrypting the session key. Consequently, the channel unique key can be obtained (and, hence, the content decrypted) only by a player that is compliant with both copy protection rules and subscription rules. The channel key can be refreshed periodically as subscriptions change or expire.

Method for ensuring content protection and subscription compliance

Tamper-resistant trusted java virtual machine and method of using the same

Sets of encryption keys useful by devices for decrypting encrypted content are defined using an error-correcting code such as a Reed-Solomon code to define vectors of length 'n' over an alphabet of (0, . . . , N&#x2212;1), wherein 'n' is the number of columns in a key matrix and &#x201c;N&#x201d; is the number of rows in the matrix. Each vector represents a set of keys that can be assigned to a device. With this invention, overlap between sets of keys can be minimized to minimize the possibility that the key set of an innocent device might be inadvertently revoked when the key set of a compromised device is revoked. Also, only the generating matrix of the error-correcting code and the index of one set of keys need be stored in memory, since all previously defined key sets can be regenerated if need be from just the generating matrix and index.

Method for assigning encryption keys

A system for protecting content on recordable media for, e.g., DVD audio disks, flash memory media, or other media includes providing a media key block (MKB) on each media, with each MKB including 25,000 encryptions of a media key by 25,000 or so device keys. Each authorized player in the system has a single device key from among the system device keys with which to decrypt the media key. To avoid a coincidence attack in which a hacker can learn the MKB and associated media key and then guess at a device key without knowing its position in the MKB, the media key is XORed with a number representing each position in the MKB, and only then encrypted with the device key corresponding to that position.

Coincidence-free media key block for content protection for recordable media

A method of evaluating a tetrahedral linear interpolation function utilizes a table preparation process and a linear interpolating process. In the table preparation process, values v and domain points p of the function are related by two tetrahedral interpolation variables denoted as a matrix T and a vector t, as follows: v=t+pT. The coordinates of p include n components, and the value v includes m components. The matrix T includes n rows and m columns, as it must to relate p to v. If the value of the function is scalar, t is also a scalar, and T is a vector of n elements. From the coordinates of the (n+1) domain input points and the function values v at these points, the values of variables t and T are computed and stored in a table. The linear interpolation procedure of the invention uses the values tabulated for t and T to calculate an approximation for the components of the function value v at a given p. The function arguments are stored in a first array of n elements denoted as p[i], and the calculated approximations are to be stored in a second array of m elements denoted as v[j]. The approximations for the array v[j] may be calculated according to the following equation: ##EQU1##

Method and means for evaluating a tetrahedral linear interpolation

The invention provides approximation of the value of a function of three variables. The invention embraces three processes: function domain packing, polyhedron extraction, and volumetric interpolation. The processes are applied to a mathematical function to calculate an approximation for the function range output value at a point which has been arbitrarily selected from the input domain of the function. Function domain packing utilizes two interlocked domain subdivisions. A first subdivision and a second subdivision each divide the domain space into rectangular solids. Each subdivision is accomplished by means of a plurality of planes of constant value corresponding to each of the input dimensions. After a function domain has been so subdivided, a tetrahedral volume is extracted from the fraction domain space. This tetrahedral volume is defined by two points from the first subdivision and two points from the second subdivision. The third process of the invention is a function approximation method using volumetric interpolation. If the fraction domain is subdivided according to the present invention, a continuous approximation of function range output values will result. The volumetric interpolation process commences by subdividing the extracted tetrahedron into four sub-tetrahedra. The subdivision is implemented by drawing lines from each of the vertices of the extracted tetrahedron to the target evaluation point to form four sub-tetrahedra.

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Morgan Hill, CA, United States of America

Sigfredo Ismael Nin