Thomson Licensing

Interdigital Ce Patent Holdings

Mohamed Karroumi

Eric Diehl

Alain Durand

Marc Joye

Stéphane Onno

Antoine Monsifrot

Yves Maetz

Olivier Heen

Charles Salmon-Legagneur

Olivier Courtay

Stephane Onno

Nicolas Prigent

Ayoub Massoudi

Benjamin Richard

Yan-Mei Tang Talpin

A device receives a password from a user, obtains a public key for a cryptographic algorithm for the device, obtains a password verifier by applying a one-way function to a combination of a unique identifier, the password and the public key, generates the certificate comprising the unique identifier, the public key and the password verifier, signs the certificate using a private key corresponding to the public key thereby obtaining a self-signed certificate, and outputs the self-signed certificate. Also provided is the device.

Device and method certificate generation

A cryptographic hash value is computed in a hardware processing unit of an apparatus. The cryptographic hash value is computed iteratively processing blocks of data in a predetermined order by, for each block: obtaining at least one intermediate value for the block by applying a function to the block, computing a value of a weight function, and updating at least one hash variable with a corresponding intermediate value only if the value of a weight function is equal to at least one predetermined value. The processing unit then generates the cryptographic hash value from the at least one hash variable.

Device and method for discontinuous hashing of digital data

A cryptographic device performs modular addition between a first integer value x and a second integer value y in a processor by: obtaining a first masked input {circumflex over (x)}, a second masked input &#x177;, a first mask rand a second mask r, the first masked input {circumflex over (x)} resulting from the first integer value x masked by the first mask rand the second masked input &#x177; resulting from the second integer value y masked by the second mask r; computing a first iteration masked carry value &#x109;, using the first masked input {circumflex over (x)}, the second masked input &#x177;, the first mask r, the second mask rand a carry mask value &#x3bb;; recursively updating the masked carry value &#x109;to obtain a final masked carry value &#x109;, wherein the masked carry value is updated using the first masked input {circumflex over (x)}, the second masked input &#x177;, the first mask r, the second mask r, and the carry mask value &#x3bb;; combining the first masked input {circumflex over (x)} and the second masked input &#x177; and the final masked value &#x109;to obtain an intermediate value; combining the intermediate value with the carry mask value to obtain a masked result; and outputting the masked result and a combination of the first mask rand the second mask r. It is preferred that the combinations use XOR.

Efficient modular addition resistant to side channel attacks

A method for distributing content in a content distribution system is disclosed which comprises the steps of: encrypting at a Content Packager a content using a content encryption key to generate an encrypted content; sending the content encryption key to a Licensing Authority; receiving from the Licensing Authority a distribution key containing an encryption of the content decryption key (K) for a given set of authorized devices; creating a secure link between the content encryption key (K) and the content protected by this content encryption key using a signature of the content; and distributing the encrypted content together with the signature of the content. A method for receiving content distributed according to the above-mentioned method in a device able to play back the content is also disclosed where the content signature is checked before any play back of the content.

Method for preventing laundering and repackaging of multimedia content in content distribution systems

A method for secured entry of personal data is disclosed. This method comprises for each item of personal data a first step of presentation of a virtual keyboard comprising keys and a first cursor, followed by a step of selection of a key corresponding to the item of personal data wherein the virtual keyboard also comprises at least one dummy cursor and wherein the position on the virtual keyboard of the at least one dummy cursor depends on the position of the first cursor. A device for secured entry of personal data configured to implement the method is further disclosed.

Method and device for secured entry of personal data

A method for discovering emulated clients. A verifier sends a cryptographic challenge C to a client and preferably starts a timer. The client uses a deterministic key search algorithm to find the correct key and returns the result as a number of tries needed. The verifier then stops the timer if this was started and verifies that the result is correct and preferably that the response was timely. Also provided is a verifier.

Device and method using non-cycle accurate measurements for discovering emulated clients

There are times when a first user may wish to distribute an excerpt of a protected digital content to a second user, for example for criticism. The protected digital content is divided into a plurality of parts, each part being encrypted using a control word specific for the part, wherein each control word can be generated from a master control word for the protected digital content. A device belonging to the first user selects the parts of the excerpt; generates the control words for the selected parts from the master control word; generates a license for the selected parts, the license comprising the control words for the selected parts; and transmits the selected parts and the license to the receiver of the second user. Also provided is the device of the first user.

Method and device for excerpt licensing

A method for performing a m-ary right-to-left exponentiation using a base x, a secret exponent d and a modulus N, wherein m is a power of 2. A device having a processor and m+1 registers R[]&#x2212;R[m] in at least one memory: initializes register R[] to h for a chosen value h, wherein the order of the value h is a divisor of m*(m&#x2212;1)/2, register R[m] to xand the registers other than R[] and R[m] to the value h; updates register R[r] to R[r] times x, wherein r is the remainder of a division of d by (m&#x2212;1) mod N; obtains a working exponent q that is the quotient of the division of d by (m&#x2212;1); performs l iterations, starting at i=0, of: setting R[q] to R[q] times R[m] and raising R[m] to the power of m, where l is the length of q in base m and qis the i-th digit of the representation of q in base m and qis non-zero; verifies the correctness of the result by checking that R[m] equals the product of registers R[]-R[m&#x2212;1] to the power of m&#x2212;1; and outputs the product of R[j], where 1&#x2266;j&#x2266;m&#x2212;1, only if the correctness is successfully verified.

Fault-resistant exponentiation algorithm

A method of generating a segment key KSmt from a given basic key KmT and a given modification key K'in a key space with M*T keys. The basic key KMT is split into two parts LmT, RmT onto which a one-way function is applied M&#x2212;m and T&#x2212;t times, respectively, and the results are combined again to form a target basic key. A one-way function is applied to the modification key K&#x2032;MT a number of times that corresponds to a distance value z between the given basic key and the segment key; in one preferred embodiment z=(M&#x2212;m)+(T&#x2212;t). This result is XOR-ed with the target basic key to obtain the segment key KSAlso provided is a device.

Method and device for key generation

A method of encrypting compiled computer code instructions to be decrypted instruction by instruction during execution. The computer code instructions are encrypted using a chaining mode so that an encrypted instruction depends on the values of the instruction, the value of the preceding instruction and a pseudo-random number. As it may happen that the instruction can be arrived at from more than one preceding instruction, at least one of the preceding instructions is associated with a random number compensator for use during decryption of the encrypted instruction, so that the decryption of the encrypted instruction yields the same result regardless of which the preceding instruction was. Also provided are an encryption device, a decryption device and method, and a digital support medium storing encrypted compiled computer code instructions.

Methods and devices for instruction level software encryption

The present invention concerns a method and a device for encrypting an encoded scalable enhancement frame sent by an emitter to a receiver, the enhancement frame comprising a plurality of complementary streams ordered in term of quality level, each complementary stream corresponding to a combination of more than one scalability type, where a complementary stream of a lower quality level corresponds to a lower quality on each scalability type, comprising at the level of the emitter the steps of generating a key per complementary stream for encrypting said complementary stream in such a way that all scalability types can be either simultaneously or individually used, said keys being generated in such a way that only the keys of the complementary streams of quality levels lower than the quality level of a complementary stream can be obtained from the key of said complementary stream, and sending the key of a complementary stream corresponding to a required quality level to the receiver, the key permitting a receiver to generate the keys of the complementary streams of the lower quality levels only. The present invention also concerns a method and a device for decrypting a received encoded scalable enhancement frame.

Method and device for managing a transmission of keys

An encryption chaining mode takes plaintext block N, generates encryption key N by combining, preferably by XOR, encryption key N-and plaintext block N-and encrypts plaintext block N using an encryption algorithm with encryption key N to output ciphertext block N. Encryption key for the first plaitnext block is generated by XOR-ing a random Initialization vector and a random intialization key K. In a preferred embodiment, initialization key K is subkeys resulting form a key schedule algorithm and encryption key N-is only one of the subkeys. Encryption key for the first plaintext block is generated by XOR-ing a random Initialization vector and one subkey resulting form a key schedule algorithm. Also provided is a corresponding decryption method, an encryption device, a decryption device.

Growing community of inventors

Rennes, France

Mohamed Karroumi