The aim of this thesis is to explain theoretical and mathematical point of view the principle of elliptic curve cryptography, which at present appears as the most petential representative of asymmetric cryptography. The introduction describes basic mathematical assumptions and knowledge which are used in cryptography and in other parts of the thesis we build on them. I visualize elliptic curve cryptosystem, describe the mathematical principle of operation and then show algorithm, which is based cryptosystem. Thesis will continue comparing this cryptosystem with key members of the asymmetric cryptography. These are algorithms RSA and ElGamal. Comparison of these cryptosystems effect mainly from the theoretical point of view and with the help...