Threedecadesagopublic-keycryptosystemsmadea revolutionarybreakthrough in cryptography. They have developed into an indispensable part of our m- ern communication system. In practical applications RSA, DSA, ECDSA, and similar public key cryptosystems are commonly used. Their security depends on assumptions about the di?culty of certain problems in number theory, such as the Integer Prime Factorization Problem or the Discrete Logarithm Problem. However,...