# Marc Joye, Cesson-Sevigne FR

## Marc Joye, Cesson-Sevigne FR

Patent application number | Description | Published |
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20090175455 | METHOD OF SECURING A CALCULATION OF AN EXPONENTIATION OR A MULTIPLICATION BY A SCALAR IN AN ELECTRONIC DEVICE - A cryptographic operation includes calculating a multiplication of an element of an additively denoted group by a scalar. After two registers R | 07-09-2009 |

20090323934 | Method for calculating compressed RSA moduli - A method for generating a compressed RSA modulus, allowing up to two thirds of the bits of a modulus N to be fixed. N has a predetermined portion N | 12-31-2009 |

20100091983 | METHOD AND A DEVICE FOR GENERATING COMPRESSED RSA MODULI - Method and device for generating factors of a RSA modulus N with a predetermined portion N | 04-15-2010 |

20100208884 | Method and device for hashing onto points of an elliptic curve - Hashing onto elements of a group, in particular onto points of an elliptic curve. An input message is run through a “regular” hashing algorithm, such as e.g. SHA-1 and MD5, and used as a scalar in multiplication with an element of the group. The result is necessarily also an element of the group. An advantage is that the security of the hashing algorithm is the same as that of the underlying “regular” hashing algorithm. Also provided is a device. | 08-19-2010 |

20100208887 | Method and device for countering faul attacks - The public exponent e of an RSA key is embedded in a RSA key object that lacks this exponent. During exponentiation, the public exponent e may be extracted and used to verify that the result of the exponentiation is correct. The result is output only if this is the case. The invention counters fault-attacks. Also provided are an apparatus and a computer program product. | 08-19-2010 |

20100232599 | Fault-resistant calculcations on elliptic curves - Means for checking the correctness of a cryptographic operation on an elliptic curve E(Z/pZ), including fault-resistant computation of Q=kP on elliptic curve E(Z/pZ). Elliptic curve Ê(Z/pr | 09-16-2010 |

20100310066 | APPARATUS AND A METHOD FOR CALCULATING A MULTIPLE OF A POINT AN ELLIPTIC CURVE - A device and a method for calculating a multiple of a point on an elliptic curve from the right to the left by repeated point doubling and point addition. Each point doubling is evaluated with an extended set of coordinates and each point addition is evaluated by taking as input a restricted set of the extended set of coordinates. The at least one coordinate of the extended set that is not part of the restricted set is stored in a memory between each iteration of the point doubling. This can enable speeding up the calculations as compared to prior art solutions. Also provided is a computer program product. | 12-09-2010 |

20110016311 | METHOD FOR PREVENTING LAUNDERING AND REPACKAGING OF MULTIMEDIA CONTENT IN CONTENT DISTRIBUTION SYSTEMS - 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 | 01-20-2011 |

20110085659 | Method and apparatus for generating a signature for a message and method and apparatus for verifying such a signature - A method of generating a signature σ for a message m, the method enabling online/offline signatures. Two random primes p and q are generated, with N=pq; two random quadratic residues g and x are chosen in Z* | 04-14-2011 |

20120039461 | EXPONENTIATION METHOD RESISTANT AGAINST SIDE-CHANNEL AND SAFE-ERROR ATTACKS - An exponentiation method resistant against side-channel attacks and safe-error attacks. Input to the method is g in a multiplicatively written group G and a /-digit exponent d with a radix m>1 and output is z=(d−1) is expressed as a series of (/−1) non-zero digits, d* | 02-16-2012 |

20120087491 | A METHOD AND A DEVICE FOR PERFORMING TORUS-BASED CRYPTOGRAPHY - At CRYPTO 2003, Rubin and Silverberg introduced the concept of torus-based cryptography over a finite field. The present invention extends their setting to the ring of integers modulo N, thus obtaining compact representations for cryptographic systems that base their security on the discrete logarithm problem and the factoring problem. This can result in small key sizes and substantial savings in memory and bandwidth. However, unlike the case of finite field, analogous trace-based compression methods cannot be adapted to accommodate the extended setting of the invention when the underlying systems require more than a mere exponentiation. The invention finds particular application in a torus-based implementation of the ACJT group signature scheme. Also provided is a processor. | 04-12-2012 |