Cryptography is as old as human communication itself, but has undergone a revolution in the last few decades. It is now about much more than “secret writing” and includes seemingly paradoxical notions such as communicating securely without a shared secret, and computing on encrypted data. In this challenging but rewarding course we will start from the basics of private and public key cryptography and go all the way up to advanced notions such as fully homomorphic encryption and indistinguishability obfuscation.