Foundations of Cryptography: Volume 1, Basic Tools
Why this book?
If you want to compose or play music, you need to know some basic music theory: notes, scales, chords, and so on. Likewise, solid cryptography knowledge requires understanding its foundations: concepts such as one-way function, pseudorandom generators, computational hardness, secure encryption, and zero-knowledge proofs. Goldreich’s books are the best starting point for those who want to delve into cryptography theory.