Foundations of Cryptography surveys the main paradigms, approaches and techniques used to conceptualize, define and provide solutions to natural cryptographic problems. The author starts by presenting some of the central tools; that is, computational difficulty (in the form of one-way functions), pseudorandomness, and zero-knowledge proofs. Based on these tools, the emphasis is shifted to the treatment of basic applications such as encryption and signature schemes as well as the design of general secure cryptographic protocols. The author has created a unique overview that includes well over 1.;Introduction and Preliminaries; Introduction; Preliminaries; I Basic Tools; Computational Difficulty and One-way Functions; One-way functions; Hard-core predicates; Pseudorandomness; Computational indistinguishability; Pseudorandom generators; Pseudorandom functions; Zero-Knowledge; The simulation paradigm; The actual definition; Zero-knowledge proofs for all NP-assertions and their applications; Variants and issues; II Basic Applications; Encryption Schemes; Definitions; Constructions; Beyond eavesdropping security; Signature and Message Authentication Schemes; Definitions; Constructions.