protocollo e casi studio Bitcoin: protocollo e casi studio Francesco Santini Qui posso scrivere delle note Dipartimento di Matematica e Informatica Università di Perugia 1

What is and what is not Bitcoin was invented in 2008 with the publication of a paper titled “Bitcoin: A Peer- to-Peer Electronic Cash System”, by a programmer under the pseudonym of Satoshi Nakamoto. Bitcoin is not “simply” a digital currency, but a network of trust that could also provide the basis for so much more than just currencies. Digital rights management, e-voting, smart contracts, national DLT (permissioned), block-chain oriented public services

More gold than coins Today, 1 bitcoin = 3330.37 euro

The P2P Network

Chart last bitcoin mined in year 2140

Nodes Bitcoin is an open source project The first impementation is Bitcoin Core

Creation of keys/addresses

Transactions Bitcoin addresses are pseudonyms of real individuals (one can have several pseudonyms)

Chain of Transactions

Script A locking script is a spending condition placed on an output: it specifies the conditions that must be met to spend the output in the future An unlocking script is a script that “solves,” or satisfies, the conditions placed on an output by a locking script and allows the output to be spent.

Locking and unlocking script

Locking and unlocking script

Locking and unlocking script

Miners and proof-of-work After validating transactions, a bitcoin node will add them to the memory pool, or transaction pool, where transactions await until they can be included (mined) into a block A miner aims at finding a random nonce (32 bit) that becomes part of a block and makes it have a hash that starts with a given amount of zeroes The hash needs to be less in value than the current target. The target is a 256-bit number (extremely large) that all Bitcoin nodes share.

Hashing power

Block-chain

Thanks for your attention Contacts: francesco.santini@dmi.unipg.it 17