Abstract: The invention relates to a method for personalizing a secure processor in a NFC system to execute a secure application, comprising steps of obtaining by a server identification data of a user memorized in a secure storage medium, personalization data corresponding to the user identification data, and identification data of a NFC system of the user, comprising an encryption key of the secure processor, encrypting by the server personalization data using the encryption key, transmitting to the NFC system encrypted personalization data, receiving by the secure processor encrypted personalization data, deciphering personalization data, and memorizing in a secured way personalization data by the secure processor.

Abstract: An integrated circuit including a multiplication function configured to execute a multiplication operation of two binary words x and y including a plurality of basic multiplication steps of components xi of word x by components yj of word y is described. The multiplication function of the integrated circuit is configured to execute two successive multiplications by modifying, in a random or pseudo-random manner, an order in which the basic multiplication steps of components xi by components yj are executed.

Abstract: A process for testing an integrated circuit includes collecting a set of points of a physical property while the integrated circuit is executing a multiplication, dividing the set of points into a plurality subsets of lateral points, calculating an estimation of the value of the physical property for each subset, and applying to the subset of lateral points a step of horizontal transversal statistical processing by using the estimations of the value of the physical property, to verify a hypothesis about the variables manipulated by the integrated circuit.

Abstract: A cryptographic method carries out a modular exponentiation of the type C=A<B1> mod N, where A is an operand, B1 is a first exponent, N is a modulus and C is a result. The method includes the steps of masking the operand A by a number s, carrying out a modular exponentiation of the masked operand by the exponent B1, and demasking the result of the exponentiation, by removing a contribution from the random number s from the result of the exponentiation. During the step of masking the operand A, the operand A is multiplied by a parameter of the form K<s.B2>, where K is a constant and B2 is a second exponent such that B1.B2=1 mod N. The method is implemented preferably by using a Montgomery multiplier. The preferred choice for the constant K is K=2p, p being an integer lying between 0 and n, n being an upper bound of the size of the modulus N and conventionally depending on the choice of implementation of the Montgomery multiplication.

Abstract: A process for testing an integrated circuit includes collecting a set of points of a physical property while the integrated circuit is executing a multiplication, dividing the set of points into a plurality subsets of lateral points, calculating an estimation of the value of the physical property for each subset, and applying to the subset of lateral points a step of horizontal transversal statistical processing by using the estimations of the value of the physical property, to verify a hypothesis about the variables manipulated by the integrated circuit.

Abstract: An integrated circuit including a multiplication function configured to execute a multiplication operation of two binary words x and y including a plurality of basic multiplication steps of components xi of word x by components yj of word y is described. The multiplication function of the integrated circuit is configured to execute two successive multiplications by modifying, in a random or pseudo-random manner, an order in which the basic multiplication steps of components xi by components yj are executed.

Abstract: A countermeasure method in an electronic component implementing an asymmetric private key encryption algorithm includes generating a first output data, using a primitive, and a protection parameter, transforming, using the protection parameter, at least one element of a set consisting of the private key and an intermediate parameter obtained from the first output data, to respectively supply first and second operands, and generating, from an operation involving the first and second operands, a second output data.

Abstract: A method of protecting a microcircuit against attacks aimed at discovering secret data used on the execution, by the microcircuit, of an encryption algorithm includes generating at least one protection parameter for the secret data and modifying the execution of the encryption algorithm through that protection parameter. Generation of the at least one protection parameter includes defining a function generating, by successively applying to at least one secret parameter which is stored in memory, a sequence of values which can only be determined from that secret parameter and that function, and to generate the protection parameter in a reproducible way from at least one value in that sequence.

Abstract: The invention relates to a cryptographic method that incorporates a modular exponentiation secured against hidden channel attacks, without requiring knowledge of the public exponent. The method includes a modular exponentiation and the following steps: drawing of a random value s; initialization of variables with the aid of s; application of an algorithm enabling a loop invariant to be retained by virtue of the properties of the Montgomery multiplier Mgt; unmasking of the result of the algorithm to obtain the signature of the message.

Abstract: A cryptographic method carries out a modular exponentiation of the type C=A<B1> mod N, where A is an operand, B1 is a first exponent, N is a modulus and C is a result. The method includes the steps of masking the operand A by a number s, carrying out a modular exponentiation of the masked operand by the exponent B1, and de masking the result of the exponentiation, by removing a contribution from the random number s from the result of the exponentiation. During the step of masking the operand A, the operand A is multiplied by a parameter of the form K<s.B2>, where K is a constant and B2 is a second exponent such that B1.B2=1 mod N. The method is implemented preferably by using a Montgomery multiplier. The preferred choice for the constant K is K=2P, p being an integer lying between 0 and n, n being an upper bound of the size of the modulus N and conventionally depending on the choice of implementation of the Montgomery multiplication.

Abstract: The invention relates to a method for personalizing a secure processor in a NFC system to execute a secure application, comprising steps of obtaining by a server identification data of a user memorized in a secure storage medium, personalization data corresponding to the user identification data, and identification data of a NFC system of the user, comprising an encryption key of the secure processor, encrypting by the server personalization data using the encryption key, transmitting to the NFC system encrypted personalization data, receiving by the secure processor encrypted personalization data, deciphering personalization data, and memorizing in a secured way personalization data by the secure processor.