Abstract: The present invention relates to a method for protecting an electronic device against side-channel attacks. The electronic device is configured to execute a cryptographic algorithm comprising operations in a binary finite field GF(2n), n being a positive integer. The algorithm uses at least one secret variable s to be protected. The method includes: determining a random variable k, computing a masked representation M(s, k) of the secret variable s using a masking function M including an exponentiation by 2{circumflex over (?)}k, for each operation involving a sensitive variable v corresponding to the secret variable s or to an intermediate result obtained from the secret variable s, executing the operation from a masked representation M(v, k?) of the sensitive variable v, determining an output variable r from a final result obtained in the form of a masked representation M(r, k?).

Abstract: A method for executing a function secured by time synchronisation, comprising the random choice of a value of a delay from a group G2,k of n2,k possible values, the random choice being performed according to a probability law Sk, the values of the group G2,k fulfilling the following condition: wherein x0 to Xn2,k?1 are the n2,k values of the group G2,k, Sk[xI] is the probability of occurrence associated with the value Xi by the law Sk, SSk is the statistical distribution of the possible values of the accumulated delays already introduced between times tref and tsk, tsk is the time at which the microprocessor executes the first instruction of a sequence Seqk, tref is the reference time when the microprocessor executes a particular instruction, SSmaxk is the largest value of the statistical distribution SSk, and p is a real number greater than 1.3.