Abstract: A cryptographic calculation includes obtaining a point P(X,Y) from a parameter t on an elliptical curve Y2=f(X); and from polynomials X1(t), X2(t), X3(t) and U(t) satisfying: f(X1(t))·f(X2(t))·f(X3(t))=U(t)2 in Fq, with q=3 mod 4. Firstly a value of the parameter t is obtained. Next, the point P is determined by: (i) calculating X1=X1(t), X2=X2(t), X3=X3(t) and U=U(t); (ii) if the term f(X1)·f(X2) is a square, then testing whether the term f(X3) is a square in Fq and if so calculating the square root of f(X3) in order to obtain the point P(X3); (iii) otherwise, testing whether the term f(X1) is a square and, if so, calculating the square root of f(X1) in order to obtain the point P(X1); (iv) otherwise, calculating the square root of f(X2) in order to obtain the point P(X2). This point P is useful in a cryptographic application.

Abstract: A cryptographic calculation includes obtaining a point P(X,Y) from a parameter t on an elliptical curve Y2=f(X); and from polynomials X1(t), X2(t), X3(t) and U(t) satisfying: f(X1(t))·f(X2(t))·f(X3(t))=U(t)2 in Fq, with q=3 mod 4. Firstly a value of the parameter t is obtained. Next, the point P is determined by: (i) calculating X1=X1(t), X2=X2(t), X3=X3(t) and U=U(t); (ii) if the term f(X1)·f(X2) is a square, then testing whether the term f(X3) is a square in Fq and if so calculating the square root of f(X3) in order to obtain the point P(X3); (iii) otherwise, testing whether the term f(X1) is a square and, if so, calculating the square root of f(X1) in order to obtain the point P(X1); (iv) otherwise, calculating the square root of f(X2) in order to obtain the point P(X2). This point P is useful in a cryptographic application.

Abstract: A cryptographic calculation includes obtaining a point P(X,Y) from a parameter t on an elliptical curve Y2=f(X); and from polynomials X1(t), X2(t), X3(t) and U(t) satisfying: f(X1(t))·f(X2(t))·f(X3(t))=U(t)2 in Fq, with q=3 mod 4. Firstly a value of the parameter t is obtained. Next, the point P is determined by: (i) calculating X1=X1(t), X2=X2(t), X3=X3(t) and U=U(t); (ii) if the term f(X1)·f(X2) is a square, then testing whether the term f(X3) is a square in Fq and if so calculating the square root of f(X3) in order to obtain the point P(X3); (iii) otherwise, testing whether the term f(X1) is a square and, if so, calculating the square root of f(X1) in order to obtain the point P(X1); (iv) otherwise, calculating the square root of f(X2) in order to obtain the point P(X2). This point P is useful in a cryptographic application.

Abstract: There is proposed a method of generating secret and public keys vDGHV with enhanced security, implemented in a device including at least one microprocessor and a memory. The method includes generating a secret key SK corresponding the generation of a prime random number p or product of prime numbers.

Abstract: According to the present invention there is provided a method of counter-measuring against side channel attacks, the method comprising executing a block-cipher algorithm to mask intermediate variables, wherein the block-cipher algorithm comprises one or more non-linear functions, characterized in that at least one of the non-linear functions is implemented using a match-in-place function.

Abstract: A cryptographic calculation includes obtaining a point P(X,Y) from a parameter t on an elliptical curve Y2=f(X); and from polynomials X1(t), X2(t), X3(t) and U(t) satisfying: f(X1(t))·f(X2(t))·f(X3(t))=U(t)2 in Fq, with q=3 mod 4. Firstly a value of the parameter t is obtained. Next, the point P is determined by: (i) calculating X1=X1(t), X2=X2(t), X3=X3(t) and U=U(t); (ii) if the term f(X1)·f(X2) is a square, then testing whether the term f(X3) is a square in Fq and if so calculating the square root of f(X3) in order to obtain the point P(X3); (iii) otherwise, testing whether the term f(X1) is a square and, if so, calculating the square root of f(X1) in order to obtain the point P(X1); (iv) otherwise, calculating the square root of f(X2) in order to obtain the point P(X2). This point P is useful in a cryptographic application.

Abstract: There is proposed a method of generating secret and public keys vDGHV with enhanced security, implemented in a device including at least one microprocessor and a memory. The method includes generating a secret key SK corresponding the generation of a prime random number p or product of prime numbers.

Abstract: A method and apparatus are provided for reducing the energy consumption of an electronic terminal. The method implements a step of modifying the timeout-before-standby duration for said terminal after an action performed by and/or on said terminal at a current instant, depending on the membership of the current instant in a given temporal category, from among at least two predefined temporal categories.

Abstract: A cryptographic calculation includes obtaining a point P(X,Y) from a parameter t on an elliptical curve Y2=f(X); and from polynomials X1(t), X2(t), X3(t) and U(t) satisfying: f(X1(t))·f(X2(t))·f(X3(t))=U(t)2 in Fq, with q=3 mod 4. Firstly a value of the parameter t is obtained. Next, the point P is determined by: (i) calculating X1=X1(t), X2=X2(t), X3=X3(t) and U=U(t); (ii) if the term f(X1)·f(X2) is a square, then testing whether the term f(X3) is a square in Fq and if so calculating the square root of f(X3) in order to obtain the point P(X3); (iii) otherwise, testing whether the term f(X1) is a square and, if so, calculating the square root of f(X1) in order to obtain the point P(X1); (iv) otherwise, calculating the square root of f(X2) in order to obtain the point P(X2). This point P is useful in a cryptographic application.

Abstract: According to the present invention there is provided a method of counter-measuring against side channel attacks, the method comprising executing a block-cipher algorithm to mask intermediate variables, wherein the block-cipher algorithm comprises one or more non-linear functions, characterised in that at least one of the non-linear functions is implemented using a match-in-place function.

Abstract: A cryptographic calculation includes obtaining a point P(X,Y) from a parameter t on an elliptical curve Y2=f(X); and from polynomials X1(t), X2(t), X3(t) and U(t) satisfying: f(X1(t)).f(X2(t)).f(X3(t))=U(t)2 in Fq, with q=3 mod 4. Firstly a value of the parameter t is obtained. Next, the point P is determined by: (i) calculating X1=X1(t), X2=X2(t), X3=X3(t) and U=U(t); (ii) if the term f(X1)·f(X2) is a square, then testing whether the term f(X3) is a square in Fq and if so calculating the square root of f(X3) in order to obtain the point P(X3); (iii) otherwise, testing whether the term f(X1) is a square and, if so, calculating the square root of f(X1) in order to obtain the point P(X1); (iv) otherwise, calculating the square root of f(X2) in order to obtain the point P(X2). This point P is useful in a cryptographic application.

Abstract: A method and apparatus are provided for reducing the energy consumption of an electronic terminal. The method implements a step of modifying the timeout-before-standby duration for said terminal after an action performed by and/or on said terminal at a current instant, depending on the membership of the current instant in a given temporal category, from among at least two predefined temporal categories.

Abstract: The invention relates to a method of masking a plain datum b having n bits. The inventive method is characterised in that a masked datum m is produced using the following masking function: (I), wherein p is a prime number, bi is the bit at position i of plain datum b, and qi is the prime number at position i in a set of prime numbers (q1, . . . , qn). The invention also relates to a method of masking a biometric print, consisting in: determining a set of s real minutiae which are characteristic of the print; mixing and arranging the real minutiae with t false minutiae; and forming a mixed biometric datum b having n=s+t bits, such that, for any i: bi=1 if position i corresponds to a real minutia, and bi=0 if position i corresponds to a false minutia. The invention can be used to secure a security document such as a bank cheque.

Abstract: In an electronic component using a secret key cryptographic algorithm, one operation utilizes a first table for supplying output data from input data. The output data, and/or derived data, is manipulated by critical instructions. A countermeasure method involves the use of other tables such that the output data and the derived data are unpredictable. The other tables are obtained from the first table by an exclusive-OR operation with a random value, or a derived random value, on one and/or the other of the input and output data of the first table.

Abstract: A countermeasure method in an electronic component using a secret key algorithm K on an input message M executes an operation OPN(D) on input data D. A random value, of one first random information U, is generated that is of identical size as the input information D. A second random information V, is calculated by performing an exclusive OR operation between the input information and the first random information U. The operation OPN or the sequence of operations are successively executed on the first input information U and to the second random information V, supplying respectively a first random result OPN(U) and a second random result OPN(V).

Abstract: A method and associated device for checking a biometric signature by a simple and secure calculation adapted to personal objects of the chip card type. The method is based on the storage within the object of an obscured biometric signature and an associated authentication code. A terminal capturing a fingerprint compares the fingerprint data with the obscured biometric signature transmitted by the card and transfers the result of this comparison to the chip card, which validates this result with the authentication code.

Abstract: There exist numerous public key probabilistic encryption algorithms. Most of these algorithms do not have a maximum security level against someone capable of chosen ciphertext attacks. The disclosed method provides a construct to enhance the security of any public key probabilistic or deterministic encryption algorithm to achieve an optimal security level.

Abstract: A countermeasure method in an electronic component implementing an elliptical curve based public key cryptography algorithm. A new decryption integer d? is calculated such that the decryption of an encrypted message on the basis of a private key d and the number of points n of an elliptical curve provides the same result with d? as with d, by performing the operation Q=d*P, whereby P is a point of the curve. Four steps are employed in the calculation: 1) a security parameter s is determined, 2) a random number k ranging from 0-2s is drawn, 3) the integer d?=d+k*n is calculated, and 4) Q=d?.P is calculated.

Abstract: The invention relates to a method of masking a plain datum b having n bits. The inventive method is characterised in that a masked datum m is produced using the following masking function: (I), wherein p is a prime number, bi is the bit at position i of plain datum b, and qi is the prime number at position i in a set of prime numbers (q1, . . . , qn) The invention also relates to a method of masking a biometric print, consisting in: determining a set of s real minutiae which are characteristic of the print; mixing and arranging the real minutiae with t false minutiae; and forming a mixed biometric datum b having n=s+1 bits, such that, for any i: bi=1 if position i corresponds to a real minutia, and bi=0 if position i corresponds to a false minutia. The invention can be used to secure a security document such as a bank cheque.

Abstract: A cryptography method for generating probabilistic digital signatures and/or for a key-exchange a protocol and/or for an encryption algorithm is based on the use of a public key algorithm on abnormal binary elliptic curve, such as a Koblitz curve. A point P (x, y) is selected, and pairs (ki, Pi) are stored with Pi being the point corresponding to the scalar multiplication of the point P by ki. A random variable (k) is generated and a point C is calculated that corresponds to the scalar multiplication of P by k. The generation of the random variable (k) and the calculation of the point C are performed simultaneously.