blockchain

BLOCKCHAIN TECHNOLOGY!!!(1/3)

 What problem does a blockchain solve?

.A blockchain lets us agree on the state of the system, even if we don’t all trust each other! • Ultimate goal: We all need to agree on the state of some system. • How much BTC in each account? • Who owns which property? • What’s the current state of my program? • We can all agree on that if we agree on history. • Starting state + history  current state • We don’t want a single trusted arbiter of the state of the world. • We want some level of decentralization—not a single point of failure or compromise 

 How does it work?

 • A blockchain is a sequence of hash-chained records • Once you’ve seen record N, you can’t change anything in the past. • Some procedure for adding blocks to blockchain • Who gets to add blocks? How is it done? • Validity conditions for new blocks • Are transactions valid? Are digital signatures correct? Etc. • Enforced by consensus-–chains with invalid blocks won’t be accepted. • Some procedure for deciding between alternative candidate blockchains. • When Alice and Bob have different pictures of history, there’s some way for them to eventually come to agreement about who is right.