A useful measure is presented for comparison of distinct cryptosystems, including (i) the RSA algorithm, (ii) EIGamal algorithm, (iii) a cryptosystem based on radio background noise (RBN), and (iv) a new cryptosystem based on chaos phenomena. The four cryptosystems are implemented to have the same computational power, and are compared through the marginal probability mass functions (mpmf). This paper shows experimentally that the chaos-based modular dynamical cryptosystem is (i) strong to statistical cryptanalysis by leaving no patterns or hooks in the ciphertexts and (ii) faster than the selected algorithms from public-key cryptography (RSA) and elliptic curve cryptography (EIGamal).