Park, HaejungIn this thesis, we study various aspects of digital cash systems. In particular, we concentrate on two schemes, one due to Okamoto-Ohta and the other due to Eng-Okamoto. The main part of the thesis is devoted to providing more detailed explanations of the issues of divisibility and prevention of double-spending. We then study a few additional systems to explain other aspects of electronic cash.en-USThesisMathematics