Abstract: The invention relates to the general field of digital security and more particularly cryptography. In particular it proposes a device and a method of encrypting a sequence of data. The invention also relates to a cryptographic device (1) and a cryptographic method of generating a pseudo-random data sequence (13) and their favored use in the field of digital security, in particular for encrypting and decrypting data and for cryptographically hashing messages.

Abstract: A tracing method performed by a traceability device for validating a process having a purity of steps. During at least one step of the process, there is a step of receiving a marking message sent by a marking device; and a step of determining a new fingerprint as a function of the marking message and of a preceding fingerprint, by using a hash function; and a step of sending a validation message including the most recently determined new fingerprint to a validation device. During at least one step of the process, there is a step of determining an object signature as a function of the marking message by using an asymmetric signature function and a private key of the traceability device associated with a public key of the traceability device, and a step of determining a new fingerprint as a function of the object signature.

Abstract: The invention relates to a method of validating a succession of events in the life of a device (10) relative to a predefined succession of events, including the following steps: for each event of the succession: calculating a current value of a traceability mark by applying to an identifier of the event a cryptographic hashing function with parameters set by the preceding value of the traceability mark; storing this current value on the device; after the succession of events, a checking system obtaining the latest value of the traceability mark stored on the device; this system generating the value of a theoretical mark by applying the hashing function successively to identifiers taken in the order of the events of the predefined succession; and if the latest value of the traceability mark is equal to the theoretical mark, validating that the predefined succession of events has been experienced by the device.