"Key feature: Bitcoin transfer between pseudonyms (Bitcoin addresses) Bitcoin pseudonym ≡ public key of ECDSA Sender signs transfer Double spending protection: –Bitcoin network keeps history of all transactions –Transactions have timestamps  only oldest is valid Bitcoin network works as distributed time server –Binding of transaction and timestamp: ""proof-of-work : search for z: Hash(Transaction, Timestamp, z) = 00000… (0
{"Image DocumentName": "Bitcoin \u2013 a decentral payment system", "Image ImageDescription": "[Satoshi Nakamoto: Bitcoin: A Peer-to-Peer Electronic Cash System. 2008] Key feature: Bitcoin transfer between pseudonyms (Bitcoin addresses) Bitcoin pseudonym \u2261 public key of ECDSA. Sender signs transfer. Double spending protection: Bitcoin network keeps history of all transactions. Transactions have timestamps \uf0e0 only oldest is valid. Bitcoin network works as distributed time server Binding of transaction and timestamp: \u201eproof-of-work : search for z: Hash(Transaction, Timestamp, z) = 00000\u2026 (0|1)  < w. w adjusted over timer. https://www.blockchain.info.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}