Abstract: The invention concerns a method which consists in operating a key generation in an electronic component for a specific cryptographic algorithm; storing in the electronic component a prime number P and generating at least a secret prime number. In one step (a) randomly selecting (11) two integers p1? et p2? the sum of which is equal to a number p?; in a step (b) determining (12) whether the number p? is a prime number, on the basis of a combination of the prime number stored P with the numbers p1? et p2?, so as to maintain said number p? secret; in a third step (c), if the number p? is determined to be a prime number, storing (14) the numbers p1? et p2? in the electronic component; otherwise repeating steps (a) and (b).