04 - CAP Theorem, Hash

Overview

Revising

A Smart Contract in Ethereum is invoked by an externally owned account via… data field
in the context of Ethereum, a token (a.k.a. app coin) is a value for a variable or for an entry in a key/value store of a Smart Contract
- we use crypto to pay miners or validators as a reward for PoW
In a public permissioned blockchain every node can transact and view; some of those take part in consensus.

subset of nodes that maintain the blockchain by publishing new blocks
transaction are added to the bc when a minining node publishes a node
a block collates transactions
- transactions are stored and sorted in blocks

CAP is an acronym for:

consistency
- every read receives the most recent write or an error
availability
- every request receives a (non-error) response, not necessarily the most recent write
partition tolerance
- the system continues to operate despite an arbitrary number of messages being dropped by the network between nodes

Given a hash it should be impossible to find a colliding hash.

Important

The order of tx matter!

A hash code could not be random!

A hash code could not be random!

You have a deterministic algorithm → if you input something twice it must output the same thing twice!

All operations are public!

and most importantly:

No secret key involved!

FINDING A SOLUTION IS HARD BUT EVERYONE MUST BE ABLE TO CHECK IT!

In the PoW the right to publish the next block is granted by solving a puzzle.