Zero-Knowledge Proofs for Blockchains

Zero-knowledge proofs (ZKP) are used to prove the correctness of computations without revealing any other information. Zero-knowledge proofs have origins in Interactive proof systems which were introduced in the 1980’s. Last decade has seen a big leap from theory to practice, thanks to applications such as blockchains, anonymous credentials etc. Initially used for privacy preserving transactions in Zcash, these have been used in various ways in blockchain designs like Monero, ensuring anonymity of users, designing scalable Layer-2 solutions, verifiable computation in decentralised blockchain oracles and many more. These are being increasingly used in blockchain applications.The aims of this tutorial are as follows: (1) Provide background, history, evolution and theoretical foundations, (2) Discuss desirable properties of ZKP for blockchains and its applications, (3) Present some well known ZKP systems and show how they are used in blockchains, and (4) Introduce the audience to a myriad of open problems in this space.The tutorial will be self contained, no knowledge of cryptography or blockchain will be assumed.