Blockchain

Blockchain

1. What it is?

   • A decentralized databased, contained in many computers, using cryptography
     • Information is stored on blocks, which are chained together, making inputed data, inmutable
       • Decentralization of information

2. Consensus

   • A mechanism used to agree the state of a blockchain.
   • Sybil resistance mechanisms
     • Proof of Work
       • All nodes try to answer a math prob, the 1st to solve it, adds a block
         • Requieres a lot of comptutaional power
     • Proof of Stake
       • Nodes stake their money as collateral, add a block and if they misbehave, their stake gets slashed
       • Delegated PoS
     • Proof of Space
     • Proof of History
     • Proof of Elapsed time
     • Way to defend against users that want to gain a disproportionate influence over the blockchain.
   • Chain selection
     • The way to select which is the “real“ blockchain.
       • Most select the longest blockchain

3. Blocks & Hash

   • Block
     • Transactions mined together in a specific space
   • Hash
     • Unique fixed length string that helps identify a piece of data
       • Includes: the block number, the data and the previous hash
   • Hash algo
     • A math function that computes data into a hash
       • Always same output if input the same
         • No 2 sames hashes for diff inputs
           • Size of hash is always the same, regardless the input

4. Types

   • Public
     • Anyone can participate
   • Private
     • 100% centalized
   • Semi-private
     • Run by a company
   • Consortium
     • Consensus is handled only by a specific group

5. Elements

   • P2P
     • Equal nodes that communicate wtih each other
   • Cryptography
     • Secures that data sent by nodes gets unaltered
   • Consensus algo
     • Rules of blockchain
       • Prevent attack
   • Reward/punish
     • Make it convinient to contribute to the blockchain
   • Market adopt
     • Large enough to be truly decentralized

6. More

   • Advantages
     • Decentralization
     • Transparency
     • No intermediaries
     • Inmutability
     • Trustless, code ran
   • Uses and blockchains
     • Identity, property, art, governance
     • Ethereum, Bitcoin, Cardano, Stellar, Tezos, Ripple, Hyperledger, BSC,

7. Cryptography keys

   • Private key
     • Gives access to funds
   • Signature
     • Confirms transaction using private key
   • Public key
     • Alllows recieving crypto to their account
       • Public adress
         • Hashed public key