bdxcoin - blockchain 101 - 09-04-2014
DESCRIPTION
Une description technique de la blockchain.TRANSCRIPT
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 !