This companion exercise and solution book to A Classical Introduction to Cryptography: Applications for Communications Security contains a carefully revised version of teaching material used by the authors and given as examinations to advanced-level students of the Cryptography and Security Lecture at EPFL from 2000 to mid-2005. A Classical Introduction to Cryptography Exercise Book covers a majority of the subjects that make up today’s cryptology, including symmetric or public-key cryptography, cryptographic protocols, design, cryptanalysis, and implementation of cryptosystems. Exercises do not require an extensive background in mathematics, since the most important notions are introduced and discussed in many of the exercises. The authors expect the readers to be comfortable with basic facts of discrete probability theory, discrete mathematics, calculus, algebra, and computer science. Following the model of A Classical Introduction to Cryptography: Applications for Communications Security, exercises related to the more advanced parts of the textbook are marked with a star.