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Ethereum Whitepaper

Proof of Work solves two things:

provided a consensus algorithm allowing node to update bitcoin ledger

free(自由的） entry into the consensus process

Bitcoin

Mining

is the only mechanism for bitcoin to be issued, no coins are in the genesis state

to prevent the network from sybil attack (fork the chain and have over 51% of computation resources)

Multi-level data structure

Hash of a block

hash of the block header

timestamp

nonce (random number)

previous block hash

root hash of a merkle tree

Simplified payment verification → light node - download block header and relevant branches

Bitcoin Application

Name coin - first-to-file paradigm - first registerer succeeds and second fails

colored coins - allow users to issue new currencies

metacoins - different state transition functions

Two approaches towards building a consensus protocol

building an independent network → difficult to implement, too small to protect themselves followed the power rule

building a protocol on top of bitcoin → does not inherit the simplified payment verification features of bitcoin

Scripting

facilitate a weak version of a concept of smart contracts

important limitations

lack of turing-completeness → no while loop

value-blindness → UTXO all or nothing

lack of state

blockchain blindness → valuable source of randomness

Ethereum

Ethereum Accounts:

states: nonce, ether balance, contract code, storage

externally owned accounts vs. contract accounts

Transaction

the recipient of the message

a signature identifying the sender

the amount of ether transferred

data field [optional]

STARTGAS - maximum number of steps that transaction execution allowed to take

GASPRICE - unit fee sender pays per computational step

Messages

the sender of the message (implicit)

the recipient of the message

the amount of ether transferred

data field [optional]

STARTGAS - maximum number of steps that transaction execution allowed to take

State Transition Function

validate transaction form

calculate transaction fee

initialize GAS = STARTGAS

transfer the transaction value

revert state changes except payment of fee when execution failed or run out of gas, send the fee to miner

otherwise, refund the fees for remaining gas to the sender, and send consumed gas to miner

Validating block - preserve both state and transaction lists

Application type:

financial, semi-financial, non-financial

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