Quiz 2 Flashcards
Blockchain
A Platform for executing transactional services. An append-only shared ledger of digitally signed and encrypted transactions replicated across a network of peer nodes.
Block
A block is a container data structure that contains a series of transactions. Made of a block header and a list of transactions.
Block Header
Metadata about a block and the previous blocks hash
Nonce
Used to prevent duplicate hashes
Mining
The mechanism used to generate a hash for a inserting new node in blockchain
Centralized
Online social networks
Decentralized
Internet, Email service and the SMTP protocol.
Peer to peer network
Open to anyone, low barrier to entry. When Alice wants to pay Bob:
she broadcasts the transaction to all Bitcoin nodes
Consensus protocol
Which transactions were broadcasted on the network
Why is consensus hard?
Nodes may crash or be malicious
Consensus algorithm
1.New transactions are broadcast to all nodes
2.Each node collects new transactions into a block
3.In each round a random node gets to broadcast its block
4.Other nodes accept the block only if all transactions in it are valid (unspent, valid signatures)
5.Nodes express their acceptance of the block by including its hash in the next block they create
Proof of work
1.Select nodes in proportion to computing power
2.Let nodes compete for right to create block
3.Make it moderately hard to create new identities
Race Conditions
Transactions or blocks may conflict
