04 - CAP Theorem, Hash

Overview

  • Description:: CAP Theorem, Hash

Revising

  • A Smart Contract in Ethereum is invoked by an externally owned account via‚Ķ 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.

Mining nodes and validation

  • 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 Theorem

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!

Hash code

A hash code could not be random!

A hash code could not be random!

You have a deterministic algorithm ‚Üí 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!

Mining trustworth

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