In this course, you will explore the mechanics of blockchain technology and how the blockchain acts like a trusted third party. To do this, Professor Ari Juels will design a theoretical cryptocurrency from scratch to illustrate how Bitcoin and other cryptocurrencies make use of the blockchain to transfer value from person to person. Then, once you understand how the blockchain acts as a trusted ledger, you will practice articulating other transformative ways in which blockchains can change how commercial and interpersonal connections happen online.

This course will walk you through the basics of cryptography: how information has historically been disguised (encrypted) and revealed (decrypted) using mathematics. You will see how a message can be turned into a number, and how that number can be encrypted and decrypted by two complete strangers. You will practice encrypting your own message to understand the basics of what makes a good encryption scheme. Then, you will delve deeper into the specific type of cryptography used in blockchain technology -- public key cryptography - and the promises and limitations it has in carrying out the core functions of a blockchain. You will create your own theoretical gold exchange in order to more fully understand how you can send anything to anyone around the world without a middleman. Ultimately you will know exactly how information on the blockchain is secured, legitimized, and authenticated without needing a third party to verify it.

This course will teach you to understand the differences between the blockchain technology of today and the former, less accessible and less transparent blockchains of decades past. You will dig into the mechanics of the [newer] Bitcoin blockchain protocol and how it ensures the longevity of a decentralized public ledger as well as how it gets consensus for approving transactions. With that knowledge you will then work to analyze what problem(s) blockchain technology aims to solve, how it solves them, and how to make sense of the promises that developers of new blockchain protocols make.

You will analyze a sample protocol to determine why the protocol might not satisfy the key properties that make a “good” blockchain secure. You will be better prepared to critically analyze all the endless new cryptocurrencies that emerge and the underlying blockchain technology that they operate on. You will outline several industries and business purposes for which the blockchains of today make sense. You will solve a computational puzzle in Excel to better understand how transactions get verified in the Bitcoin blockchain protocol. In the course project, you will design a theoretical blockchain for a company, outlining advantages and disadvantages of the properties you will think the blockchain should have based on the unique aspects of your business.

This course provides you with the tools to discern the applicability of blockchain technology to your business model. You will do this by learning about smart contracts and how you can implement minimal trust applications for almost any task imaginable. You will analyze how smart contracts work, how they're used today, how to reason about their capabilities, and what ongoing technical challenges they pose. In the course project, you will come up with your own smart contract application and outline the challenges that might exist in its adoption. Ultimately you will walk away with the ability to answer one important question: Does your business need a blockchain?