Abstract: A method of implementing a block cipher algorithm by a device storing a fixed initialization datum includes determining, before execution of a first iteration of the algorithm in the course of a session, a modified initialization datum by way of a determined function supplied as input with the fixed initialization datum and a state value specific to the session. The state value may be stored in the device. The modified initialization datum may be used to implement the first iteration of the algorithm.

Abstract: A system and a method for cryptographic reduced-coupon reloading are provided, where a coupon includes a pseudo-random number ri=PRFK(i), where i is an index for labeling the coupon, PRF is a predetermined pseudo-random function and K is a regeneration key, and a “reduced-coupon” xi=ƒ(ri), where ƒ is a predetermined one-way function, where: a candidate device and a second device acquire a common value of a token T, the candidate device transmits a verification value vT to the second device, the second device verifies whether the verification value is equal to PRF?Q(T), where PRF? is a predetermined keyed pseudo-random function identical to, or derived from, the pseudo-random function PRF, where Q is an authentication key owned by the second device and known to the candidate device provided the candidate device is a legitimate reloading device, and if the verification is positive, one or several reduced-coupon(s) provided by the candidate device are stored in the second device.

Abstract: A method of authenticating an entity by a verification entity, said entities sharing a pair of secret keys X and Y which are n×m (n, m>i) binary matrices. The method may be applied to cryptographic protocols for authenticating electronic chips at a very low cost.

Abstract: A method and apparatus are provided for identifying and authenticating a radio tag by a radio reader. The tag forms part of a set of tags in a radio range of the reader and has selected a time slot from a set of available time slots. The method includes: a step of the reader sending a query message during the selected time slot; and a step of the reader receiving a reply message from the tag that selected the time slot. The reply message includes a random value selected by the tag. The tag stores authentication coupons and the reply from the tag received by the reader during the time slot contains, as a random value selected by the tag, a value that is a function of one of the coupons.

Abstract: A method and apparatus are provided for mutually authenticating a reader and a radio tag. The method includes: a step of the tag sending data to the reader, the data enabling an index to be determined for identifying an authentication coupon of the reader, the index being selected by the tag; a step of the reader obtaining the coupon from the determined index and of the reader sending the coupon to the tag; a step of the tag obtaining an authentication value from the selected index and of the tag verifying that the coupon received from the reader corresponds to the authentication value that is obtained, if the verification is positive, then a step of finalizing the authentication of the tag by the reader; and if the verification is negative, interrupting the mutual authentication method.

Abstract: A method is provided of implementing a block cipher algorithm by a device storing a fixed initialization datum, comprising, before execution of a first iteration of the algorithm in the course of a session, a step of determining a modified initialization datum by way of a determined function supplied as input with the fixed initialization datum and a state value specific to the session, the state value being stored in the device, said modified initialization datum being usable to implement the first iteration of the algorithm.

Abstract: An authentication method of a prover device by a verifier device by means of cryptographic coupons is provided for, wherein a coupon comprises, on one hand, a pseudo-random number ri, where i is an index for labeling the coupon, and, on the other hand, a reduced-coupon xi such that xi=ƒ(ri), where ƒ is a predetermined one-way function, comprising at least the following steps: the verifier device sends a challenge consisting of a random value c to the prover device; the prover device sends to the verifier device a response y calculated by using a pseudo-random number ri, said challenge c, and a secret key s belonging to the prover device; and the verifier device checks the validity of said response y based on the challenge c, the reduced-coupon xi corresponding to said pseudo-random number ri, and a public key V corresponding to said secret key s. According to the invention, the verifier device receives said reduced-coupon xi from a source external to the prover device.

Abstract: A system and a method for cryptographic coupon reloading are provided for, wherein a coupon comprises, on one hand, a pseudo-random number ri=PRFK(i), where i is an index for labeling the coupon, PRF is a predetermined pseudo-random function and K is a regeneration key, and, on the other hand, a “reduced-coupon” xi such that xi=ƒ(ri), where ƒ is a predetermined one-way function, characterized in that it comprises the following steps: a candidate device (1) and a second device (2) acquire a common value of a token T, said candidate device (1) transmits a verification value vT to the second device (2), the second device (2) verifies whether said verification value vT is given by vT=PRF?Q(T), where PRF? is a predetermined keyed pseudo-random function identical to, or derived from, said pseudo-random function PRF, and where Q is an authentication key owned by the second device (2) and known to the candidate device (1) provided the candidate device (1) is a legitimate reloading device (1), and if the verificati

Abstract: A method of authenticating an entity by a verification entity, said entities sharing a pair of secret keys X and Y.

Abstract: A system, method, and data structure provide for securely synchronizing passwords and/or other information between systems. The password-related information is stored in the systems in a secure manner, and a user or some other, external agent participates actively in the transmission of a new password between systems. A password update file is communicated or shared between systems to synchronize passwords.