bdxcoin - blockchain 101 - 09-04-2014

Bienvenue ! @BdxCoin

Blockchain 101Some tech flavors

● Yay, crypto !

● Bitcoins don’t exist

● The blockchain is Mining

Summary

because in cryptocurrency, there’s crypto

Yay, crypto !

What is a hash ?

data1

data2

data1

5b41362bc82b7f3d56e...

5b41362bc82b7f3d56e...

d98cf53e0c8b77c14a9...SHA-256

What is a Bitcoin address ?

Private key Public key

Wallet

Allows to spend Bitcoins :

Keep it secret !

Used to receive Bitcoins :

You can share it !

“My whole life is a lie” - everyone in this room

Bitcoins don’t exist

● There is no “bitcoin balance” stored

● Balances are computed from transaction history

Bitcoins are transactions

Transaction : simplified

transaction

input output

fee

5 BTC 4.99 BTC

0.01 BTC

Transaction : less simplified

transaction ID

inputs output

fee

4 BTC 4.5 BTC

0.01 BTC

1 BTC

change0.49 BTC

Transactions are grouped in blocks

transaction

transaction

transaction

transaction

Block

reward transaction

Blocks are chained in...

block

block

block

block

Blockchain !

time to turn off your heating system

Blockchain is mining

● Need to make sure blocks are not altered

● -> Let’s hash them !

Avoiding double spending

● Hash the block to make sure it wasn’t altered

● Include hash of the previous block to make sure all the previous blocks weren’t altered !

Block hashing

Block hashing

block

hash

block

hash

A simple hash is very fast to make : one can fork the blockchain

Problem :

● Let’s add some difficulty

● The block hash must meet certain requirements

● Difficulty regulates block generation speed

Proof of Work

● Miners try to find a valid block hash

● The first to find it broadcasts it, and gets the reward + the fees

● Without miners, no blockchain

Mining

● bitcoin.pdf

● en.bitcoin.it/wiki/Category:Technical

● live blockchain monitor : blockchain.info

More tech details ?

Thank you !