Abstract: A mutual authentication method is provided that is implemented by an electronic device. The method includes i) a phase of authenticating a system that includes determining and sending an authentication challenge, and then receiving a first authentication result, and then authenticating a system by applying a cryptographic signature verification function to the first authentication result, and ii) a phase of authenticating the electronic device that includes receiving an authentication datum, and then computing and sending a second authentication result, the computing of the second authentication result using a shared secret obtained by applying a decapsulation function of a key encapsulation mechanism to a private key of the electronic device and to the authentication datum.

Abstract: A method for carrying out secure comparison with zero of a masked input datum taking the form of a first set of n first shares of a modular additive mask, and comprising the following steps: determining a second set of intermediate data from the first shares, determining a third set of third shares of a Boolean mask of the result of the comparison from the intermediate data, the second set having a partition into a first subset and a second subset such that a result obtained by combination with exclusive-or operations of zero and of the intermediate data of the first subset, is equal to a result obtained by combination with exclusive-or operations of zero and of the intermediate data of the second subset, when and only when the input datum is equal to 0.

Abstract: A post-quantum strong authentication scheme uses a reference PIN code stored in the memory of a personal object 1. A server generates a secret ss and a corresponding cipher ct using a key encapsulation mechanism, KEM, and a public key pk of the user, and then generates a cryptographic key ss' with a one-way function, OWF, applied to the secret. An access terminal 2 receives ss' and ct, and then obtains a PIN entered by the user, encrypts the PIN with ss?, and finally transmits the encrypted PIN cPIN and ct to the personal object 1. The personal object obtains ss through KEM decapsulation of ct and, with its private key sk, generates ss' with OWF, and uses it to decrypt cPIN. Verification thereof validates a first authentication factor. The personal object generates and then sends a confirmation Know(ss) of the secret to the server, validating a second authentication factor.

Abstract: A processing method implemented by a first device including receiving first data including a challenge datum; obtaining key data including an encrypted cryptographic key which is masked by executing a cryptographic masking function; receiving an unmasking key; determining the encrypted cryptographic key by executing a cryptographic unmasking function on the basis of the unmasking key; determining a decrypted cryptographic key by a decryption by executing a decryption algorithm with white-box implementation on the basis of the encrypted cryptographic key; determining an answer datum by a cryptographic operation by executing a predetermined cryptographic algorithm on the basis of the decrypted cryptographic key and the challenge datum; and sending the answer datum to authenticate the first device.

Abstract: The invention proposes a novel type of infective countermeasure against fault injection attacks. Instead of determining the injected error before amplifying it, the novel countermeasure applies the same diffusion function to two intermediate ciphers obtained by executing a cryptographic operation on an input. The error is therefore amplified within the same intermediate ciphers, referred to as infective ciphers after diffusion. It is then possible to use diffusion functions which do not map the cipher 0 as an output equal to 0. A cipher recomposed from bits of undiffused ciphers is also generated. These infective and recomposed ciphers are XOR-combined to provide an output cipher. This approach makes it possible to adapt, by simple duplication of the pairs and associated specific diffusion functions, the protection offered by the countermeasure to a desired number of injected faults.

Abstract: A cryptographic processing method comprises the following steps: obtaining a second number determined by adding to a first number the order of a finite group or a multiple of this order; determining a quotient and a remainder by dividing the second number by a random number; obtaining a third element equal to the combination of elements equal to a first element of the finite group and in number equal to the product of the quotient and the random number; obtaining a fourth element equal to the combination of elements equal to the first element and in number equal to the remainder; determining a second element by combining the third element and the fourth element.

Abstract: The invention relates to an electronic access pass allowing a person associated with the pass to access at least one restricted-access area of a building, and to a method implemented by such a pass for accessing a restricted-access area of a building. According to some embodiments, when a pass reader authorizes access to said area after reading the pass, information selected on the basis of the restricted-access area is temporarily displayed on the pass. This makes it possible to identify the carrier within the area based on the information displayed on the pass, while at the same time limiting the possibility of information being recovered through a simple glance outside the area. Overall security is thereby improved as a result, both within the area and outside it, due to the temporary nature of the display.

Abstract: A post-quantum strong authentication scheme uses a reference PIN code stored in the memory of a personal object 1. A server generates a secret ss and a corresponding cipher ct using a key encapsulation mechanism, KEM, and a public key pk of the user, and then generates a cryptographic key ss' with a one-way function, OWF, applied to the secret. An access terminal 2 receives ss' and ct, and then obtains a PIN entered by the user, encrypts the PIN with ss?, and finally transmits the encrypted PIN cPIN and ct to the personal object 1. The personal object obtains ss through KEM decapsulation of ct and, with its private key sk, generates ss' with OWF, and uses it to decrypt cPIN. Verification thereof validates a first authentication factor. The personal object generates and then sends a confirmation Know(ss) of the secret to the server, validating a second authentication factor.

Abstract: Disclosed is a method of verifying integrity of a pair of public and private cryptographic keys within the additive group of the integers modulo N, with N being the product of two primary numbers p and q, the method including: calculating a candidate private exponent d? corresponding to a private exponent d of the private key; and executing a test of integrity. The test of integrity includes a step for verifying the coherence of the candidate private exponent d? with respect to a public exponent e of the public key and to the numbers p and q, the verification step involving a first multiple modulo of the public exponent e of the public key and a second multiple modulo of the public exponent e of the public key.

Abstract: The invention proposes a novel type of infective countermeasure against fault injection attacks. Instead of determining the injected error before amplifying it, the novel countermeasure applies the same diffusion function to two intermediate ciphers obtained by executing a cryptographic operation on an input. The error is therefore amplified within the same intermediate ciphers, referred to as infective ciphers after diffusion. It is then possible to use diffusion functions which do not map the cipher 0 as an output equal to 0. A cipher recomposed from bits of undiffused ciphers is also generated. These infective and recomposed ciphers are XOR-combined to provide an output cipher. This approach makes it possible to adapt, by simple duplication of the pairs and associated specific diffusion functions, the protection offered by the countermeasure to a desired number of injected faults.

Abstract: A method for cryptographic processing includes: storing an initial value as the current value; implementing a predetermined number of first steps, including one involving obtaining second data by applying a first cryptographic algorithm to first data, the others each involving the application of the first cryptographic algorithm to the current value and the storage of the result as the new current value; implementation of the predetermined number of second steps, including one involving the obtaining of fourth data by applying, to third data, a second cryptographic algorithm that is the inverse of the first cryptographic algorithm, the others each involving the application of the second cryptographic algorithm to the current value and the storage of the result as the new current value; and verification of the equality of the first data and the fourth data, and of the equality of the current value and the initial value.

Abstract: A processing method implemented by a first device including receiving first data including a challenge datum; obtaining key data including an encrypted cryptographic key which is masked by executing a cryptographic masking function; receiving an unmasking key; determining the encrypted cryptographic key by executing a cryptographic unmasking function on the basis of the unmasking key; determining a decrypted cryptographic key by a decryption by executing a decryption algorithm with white-box implementation on the basis of the encrypted cryptographic key; determining an answer datum by a cryptographic operation by executing a predetermined cryptographic algorithm on the basis of the decrypted cryptographic key and the challenge datum; and sending the answer datum to authenticate the first device.

Abstract: The invention relates to an electronic access pass allowing a person associated with the pass to access at least one restricted-access area of a building, and to a method implemented by such a pass for accessing a restricted-access area of a building. According to some embodiments, when a pass reader authorizes access to said area after reading the pass, information selected on the basis of the restricted-access area is temporarily displayed on the pass. This makes it possible to identify the carrier within the area based on the information displayed on the pass, while at the same time limiting the possibility of information being recovered through a simple glance outside the area. Overall security is thereby improved as a result, both within the area and outside it, due to the temporary nature of the display.

Abstract: A cryptographic processing method comprises the following steps: obtaining a second number determined by adding to a first number the order of a finite group or a multiple of this order; determining a quotient and a remainder by dividing the second number by a random number; obtaining a third element equal to the combination of elements equal to a first element of the finite group and in number equal to the product of the quotient and the random number; obtaining a fourth element equal to the combination of elements equal to the first element and in number equal to the remainder; determining a second element by combining the third element and the fourth element.

Abstract: A method for determining a first integrity sum including the following steps: determining a first masked item of data by application of an “exclusive OR” operation between a first item of data and a first data mask; —determining a second item of data by application to the first masked item of data of a first cryptographic function, the second item of data being masked by a second data mask; —determining a second integrity sum associated with the second item of data by application to the second item of data of a checksum function; and determining the first integrity sum by application of an “exclusive OR” operation between the second integrity sum and a third integrity sum associated with the second data mask. A computer program and an electronic entity are also described.

Abstract: Disclosed is a method of verifying integrity of a pair of public and private cryptographic keys within the additive group of the integers modulo N, with N being the product of two primary numbers p and q, the method including: calculating a candidate private exponent d? corresponding to a private exponent d of the private key; and executing a test of integrity. The test of integrity includes a step for verifying the coherence of the candidate private exponent d? with respect to a public exponent e of the public key and to the numbers p and q, the verification step involving a first multiple modulo of the public exponent e of the public key and a second multiple modulo of the public exponent e of the public key.

Abstract: A method for determining a first integrity sum including the following steps: determining a first masked item of data by application of an “exclusive OR” operation between a first item of data and a first data mask; —determining a second item of data by application to the first masked item of data of a first cryptographic function, the second item of data being masked by a second data mask; —determining a second integrity sum associated with the second item of data by application to the second item of data of a checksum function; and determining the first integrity sum by application of an “exclusive OR” operation between the second integrity sum and a third integrity sum associated with the second data mask. A computer program and an electronic entity are also described.

Abstract: A method for cryptographic processing includes: storing an initial value as the current value; implementing a predetermined number of first steps, including one involving obtaining second data by applying a first cryptographic algorithm to first data, the others each involving the application of the first cryptographic algorithm to the current value and the storage of the result as the new current value; implementation of the predetermined number of second steps, including one involving the obtaining of fourth data by applying, to third data, a second cryptographic algorithm that is the inverse of the first cryptographic algorithm, the others each involving the application of the second cryptographic algorithm to the current value and the storage of the result as the new current value; and verification of the equality of the first data and the fourth data, and of the equality of the current value and the initial value.

Abstract: Disclosed are methods and systems of implementing a right over a content or contents. Various implementations may include means and operations for receiving, for example in an execution environment and from a secure element, a first key for implementing a right over an encrypted content; decrypting said content in said execution environment with the help of the first key; and implementing the right over the content in said execution environment. Various implementations may also include means and operations for receiving a second key in, for example, said execution environment, from the secure element; and encrypting said content in sad execution environment with the help of the second key.

Abstract: Disclosed are methods and systems of implementing a right over a content or contents. Various implementations may include means and operations for receiving, for example in an execution environment and from a secure element, a first key for implementing a right over an encrypted content; decrypting said content in said execution environment with the help of the first key; and implementing the right over the content in said execution environment. Various implementations may also include means and operations for receiving a second key in, for example, said execution environment, from the secure element; and encrypting said content in sad execution environment with the help of the second key.