The main mathematical mechanism chosen by NIST (National Institute of Standards and Technology) for standardization is the lattice, while the hash function mechanism is an alternative. Unlike isogenies of elliptic curves, these mechanisms use a larger size of both public keys and signatures. Using the example of aggregate signature protocol based on isogenies of elliptic curves, we will show how the masking method can be used to prevent the main attack on this mechanism, while obtaining a smaller signature size. Post-quantum cryptography, aggregate signature, isogenies