Patents by Inventor Marc Girault

Marc Girault has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7356842
    Abstract: A cryptographic method and a chip card which is used to carry out the method. Before any calculation is performed by a computing means of the chip card, the chip card reads (2) an integral list, in a storage means of a second entity, of identifiers of first proprietary entities of a chip card. Such list is linked to each status assigned to each of the first entities by the second entity. Subsequently, the chip card compares (3) the identifier stored in a storage means of the chip card with the contents of the list, in order to authorize (5) or prohibit (4) any calculation by the computing means depending on the result of the comparison.
    Type: Grant
    Filed: January 15, 2003
    Date of Patent: April 8, 2008
    Assignee: France Telecom
    Inventors: Sébastien Canard, Marc Girault, Jacques Traore
  • Publication number: 20080046310
    Abstract: The invention relates to a method for generating a list signature for a message to be signed, said method comprising steps which are carried out by an electronic material support of a member of a list. During said step, the electronic material support only generates an electronic signature according to a sequence number supplied to the electronic material support by a certifying authority, according to evidence of belonging to the list of members, to data relating to the electronic material support, and optionally to a key of an authority qualified to lift the anonymity of the generated signature.
    Type: Application
    Filed: May 18, 2005
    Publication date: February 21, 2008
    Applicant: France Telecom
    Inventors: Sebastien Canard, Marc Girault, Jacques Traore
  • Patent number: 7330549
    Abstract: The invention relates to a group of public-key cryptography schemas that use the discrete logarithm problem with the purpose of reducing the cost of developing, producing and maintaining a cryptographic unit. One of the entities (10) performs a calculation comprising at most a small number of additions, subtractions and multiplications of integers, said calculation being common to all of the schemas of the group. The aforementioned calculation is preferably the main calculation to be performed by the entity in question while most of the other calculations can be performed in advance. In particular, said calculation is of the y=ar+bs type, wherein r is a random number and s is a secret key that is specific to the entity (10). The calculation is common to a group of schemas for entity authentication, message authentication, digital signatures and key exchange.
    Type: Grant
    Filed: August 16, 2002
    Date of Patent: February 12, 2008
    Assignee: France Telecom
    Inventor: Marc Girault
  • Publication number: 20070260882
    Abstract: A technique for secure delegation of calculation of a value f(X,Y) of a bilinear application in a computational server. The technique comprises: selection of two secret parameters a and b; calculation of the numbers Xa and Yb; supply of the two numbers Xa and Yb to the computational server; calculation of f(Xa,Yb) by said server; receipt of the value of f(Xa,Yb) from the server; extraction of the abth root of f(Xa,Yb).
    Type: Application
    Filed: October 21, 2005
    Publication date: November 8, 2007
    Inventors: David Lefranc, Marc Girault
  • Patent number: 7284122
    Abstract: A cryptographic method of protection against fraud in transactions between an application and an electronic chip of a user. Both the electronic chip and the application compute a certificate (Sp, S) which is the result of applying a non-linear function f to a list of arguments (e1, e2) comprising at least a seed R and a secret key KO. A second secret key K? which is known only to the electronic chip and to the application is allocated to and kept secret in the electronic chip. Upon each authentication of the electronic chip, a mask M is determined by computing it from at least a portion of the secret key K?. The value of the certificate (Sp) is masked by means of the mask M to make available to the application only the masked value of the certificate (Spm). The application is used to verify the masked value of the certificate (Spm) computed by the electronic chip.
    Type: Grant
    Filed: March 19, 2001
    Date of Patent: October 16, 2007
    Assignee: France Telecom
    Inventors: Henri Gilbert, Marc Girault
  • Patent number: 7228418
    Abstract: The present invention relates to an authentication method using small-sized commitments and systems thereof. According to the invention the size of the commitment is reduced but the time the entity to be authenticated takes to respond to the authenticating entity is checked and said time is required to be lower than a certain value. The security level is maintained. Application to methods of authentication (of entities or messages) or message signature.
    Type: Grant
    Filed: April 7, 2000
    Date of Patent: June 5, 2007
    Assignee: France Telecom
    Inventor: Marc Girault
  • Patent number: 7194632
    Abstract: A secure biometric authentication method, comprising communication of biometric data to a verification module. The invention is characterized in that it consists in encrypting the biometric data with a cryptographic algorithm and in introducing for each cryptographic operation carried out a different diversification value.
    Type: Grant
    Filed: June 22, 2001
    Date of Patent: March 20, 2007
    Assignee: France Telecom
    Inventors: Didier Guerin, Marc Girault
  • Patent number: 7184547
    Abstract: Authentication and signature process with reduced number of calculations. The process involves a first entity called the “prover”, which possesses a public key v and a secret key s, these keys verify the relation v=s?t (mod n), where n is an integer called modulus and t is a parameter, and a second entity called a “verifier”, which knows the public key v. This process implies exchange of information following a “zero-knowledge protocol” between the verifier and the prover and cryptographic calculations on this information, some calculations being carried out “modulo n”. The process of the invention is characterised by the fact that the modulus n is specific to the prover that communicates this modulus to the verifier.
    Type: Grant
    Filed: January 26, 2000
    Date of Patent: February 27, 2007
    Assignee: France Telecom
    Inventors: Marc Girault, Jean-Claude Pailles
  • Patent number: 7165177
    Abstract: The present invention relates to a method of protecting an electronic chip (1) of a user against fraud in transactions between an application (2) and the electronic chip (1).
    Type: Grant
    Filed: March 19, 2001
    Date of Patent: January 16, 2007
    Assignee: France Telecom
    Inventors: Henri Gilbert, Marc Girault
  • Publication number: 20060015737
    Abstract: The invention concerns a list signature method comprising: an organization phase whereby reliable authority defines parameters for implementing an anonymous electronic signature; a phase which consists in registering persons on a list of authorized members to generate a list signature, during which each person calculates a private key, and the reliable authority delivers to each person a certificate for membership of the list; a phase which consists in defining a serial number; a phase wherein a member of the list generates by means of certificate a signature containing an element common to all the signatures issued by one single member with one single serial number; a phase which consists in verifying whether the signature has been generated by a member of the list and whether the serial number has been used to generate the signature.
    Type: Application
    Filed: July 16, 2003
    Publication date: January 19, 2006
    Inventors: Sebastien Canard, Marc Girault, Jacques Traore
  • Publication number: 20050220298
    Abstract: The invention concerns a cryptographic method whereby a second entity (B) verifies by means of a public key, a proof provided by a first entity (A), which consists in the generation by the first entity (A) of a first random number r much higher than any first integer s included in a private key kept secret by the first entity (A). The first entity (A) generates a first element of proof resulting from a modulo n exponentiation of a first integer G included or not in said public key and whereof the exponent is the first random number r. In combination with the first element of proof, a so-called common number, is generated so that the second entity (B) and the first entity (A) should have knowledge of the common number. The first entity (A) generates an image y of said private key by linear combination of the first random number r and of at least a first private key integer s. At least a multiplicative coefficient of the linear combination is said common number.
    Type: Application
    Filed: December 16, 2002
    Publication date: October 6, 2005
    Applicant: France Telecom
    Inventors: Marc Girault, Jean-Jacques Quisquater
  • Publication number: 20050213769
    Abstract: The cryptographic method is used in transactions for which a first entity generates, by means of a private RSA key, a proof verifiable by a second entity by means of a public RSA key associated with said private key. The public key includes an exponent and a module. The first entity generates a first element of proof by a calculation that can be performed independently of the transaction, and a second element of proof related to the first element of proof and which depends on a common number shared by the first and the second entities specifically for the transaction. The second entity verifies that the first element of proof is related, modulo the module of the public key, to a power of a generic number, with an exponent equal to a linear combination of the common number and of a product of the exponent of the public key by the second element of proof.
    Type: Application
    Filed: June 27, 2003
    Publication date: September 29, 2005
    Inventors: Marc Girault, Jean-Claude Pailles
  • Publication number: 20050169461
    Abstract: A cryptographic method and apparatus for anonymously signing a message. Added to the anonymous signature is another signature which is calculated (operation 13) using a private key common to all the members of a group authorized to sign and unknown to all revoked members. The private key is updated (operations 8, 11) at group level on each revocation within the group and at member level only on anonymous signing of a message by the member.
    Type: Application
    Filed: December 13, 2002
    Publication date: August 4, 2005
    Inventors: Sebastien Canard, Marc Girault, Jacques Traore
  • Publication number: 20050097336
    Abstract: A cryptographic method and a chip card which is used to carry out the method. Before any calculation is performed by a computing means of the chip card, the chip card reads (2) an integral list, in a storage means of a second entity, of identifiers of first proprietary entities of a chip card. Such list is linked to each status assigned to each of the first entities by the second entity. Subsequently, the chip card compares (3) the identifier stored in a storage means of the chip card with the contents of the list, in order to authorize (5) or prohibit (4) any calculation by the computing means depending on the result of the comparison.
    Type: Application
    Filed: January 15, 2003
    Publication date: May 5, 2005
    Applicant: France Telecom
    Inventors: Sebastien Canard, Marc Girault, Jacques Traore
  • Publication number: 20050081038
    Abstract: The invention concerns a system enabling a member (M) of a group (G) to produce, by means of customized data (z; K), a message (m) accompanied by a signature (8) proving to a verifier that the message originates from a member of the group (G). The invention is characterized in that the customized data is in the form of an electronic physical medium (26). Advantageously, the latter also incorporates: encrypting means (B3) for producing a customized cipher (C) from the customized data prior to the signature S of the message (m), means (B5) for producing a combination of a message m to be signed and the cipher (C) associated with said message, for example in the form of a concatenation of the message (m) with the cipher (C), and means (B6) for signing (Sig) the message (m) with the customized data (z; K) in the form of a cipher (C) associated with said message. Advantageously, the physical medium is a smart card (26) or the like.
    Type: Application
    Filed: December 20, 2002
    Publication date: April 14, 2005
    Inventors: David Arditti Modiano, Sebastien Canard, Marc Girault, Jacques Traore
  • Publication number: 20050018841
    Abstract: The invention relates to a group of public-key cryptography schemas that use the discrete logarithm problem with the purpose of reducing the cost of developing, producing and maintaining a cryptographic unit. One of the entities (10) performs a calculation comprising at most a small number of additions, subtractions and multiplications of integers, said calculation being common to all of the schemas of the group. The aforementioned calculation is preferably the main calculation to be performed by the entity in question while most of the other calculations can be performed in advance. In particular, said calculation is of the y=ar+bs type, wherein r is a random number and s is a secret key that is specific to the entity (10). The calculation is common to a group of schemas for entity authentication, message authentication, digital signatures and key exchange.
    Type: Application
    Filed: August 16, 2002
    Publication date: January 27, 2005
    Inventor: Marc Girault
  • Publication number: 20040240672
    Abstract: A public key cryptographic method based on groups of braids. The method employs a secret key defined by a representative s of a given braid S in a braid group G, a public key defined by a representative v of the braid T(S) converted from the braid S by an operator T, and an operation of verifying the equality of two braids, i.e. the equivalence of representatives of the two braids.
    Type: Application
    Filed: April 16, 2004
    Publication date: December 2, 2004
    Inventors: Marc Girault, Jean-Francois Misarsky, Patrick Dehornoy, Herve Sibert
  • Publication number: 20040193890
    Abstract: An asymmetrical cryptographic method of protecting an electronic chip against fraud in transactions between the electronic chip and an application, involving calculating an authentication value V from input parameters in the electronic chip. The chip produces a pseudo-random number r specific to the transaction by means of a serial pseudo-random generator included in the chip. The chip sends the application a parameter x calculated by the application prior to the transaction, linked to the random number r by a mathematical relationship, and stored in a data memory of the chip. The chip calculates a parameter y constituting the whole or a portion of the authentication value V by means of a serial function whose input parameters are at least the random number r specific to the transaction and a private key s belonging to an asymmetrical pair of keys.
    Type: Application
    Filed: January 20, 2004
    Publication date: September 30, 2004
    Applicant: France Telecom
    Inventor: Marc Girault
  • Publication number: 20040107353
    Abstract: The present invention relates to a cryptographic method of protecting an electronic chip against fraud and a device including an electronic chip which is adapted to protect the electronic chip against fraud.
    Type: Application
    Filed: September 25, 2003
    Publication date: June 3, 2004
    Applicant: FR ANCE TELECOM
    Inventors: David Arditti, Jacques Burger, Henri Gilbert, Marc Girault, Jean-Claude Pailles
  • Publication number: 20040015705
    Abstract: The invention concerns a secure biometric authentication method, comprising communication of biometric data to a verification module. The invention is characterised in that it consists in encrypting the biometric data with a cryptographic to graphic algorithm and in introducing for each cryptographic operation carried out a different diversification value.
    Type: Application
    Filed: June 30, 2003
    Publication date: January 22, 2004
    Inventors: Didier Guerin, Marc Girault