Efficient Distributed Computation Modulo a Shared Secret -- Multiparty Computation, an Introduction -- Foundations of Modern Cryptography -- Provable Security for Public Key Schemes -- Efficient and Secure Public-Key Cryptosystems.The aim of this text is to treat selected topics of the subject of contemporary cryptology, structured in five quite independent but related themes: - efficient distributed computation modulo a shared secret - multiparty computation - foundations of modern cryptography - provable security for public key schemes - efficient and secure public-key cryptosystems.