Двойная трата (Double-Spending)
Риск потратить одни и те же деньги дважды.
Double-spending is the central problem that all digital currency systems must solve. Since digital information is infinitely reproducible, a user could theoretically 'copy and paste' a digital coin to spend it twice. Centralized systems solve this with a master ledger (bank). Decentralized systems like Bitcoin solve it using Consensus Mechanisms (Proof of Work) and a globally shared blockchain, where transactions are timestamped and verified by a network of nodes.
graph LR
Center["Двойная трата (Double-Spending)"]:::main
Pre_blockchain["blockchain"]:::pre --> Center
click Pre_blockchain "/terms/blockchain"
Pre_hashing["hashing"]:::pre --> Center
click Pre_hashing "/terms/hashing"
Pre_cryptography["cryptography"]:::pre --> Center
click Pre_cryptography "/terms/cryptography"
Rel_51_percent_attack["51-percent-attack"]:::related -.-> Center
click Rel_51_percent_attack "/terms/51-percent-attack"
Rel_consensus_algorithm["consensus-algorithm"]:::related -.-> Center
click Rel_consensus_algorithm "/terms/consensus-algorithm"
Rel_block_reorgs["block-reorgs"]:::related -.-> Center
click Rel_block_reorgs "/terms/block-reorgs"
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🧒 Простыми словами
Если ты даришь другу бумажный самолетик, у тебя его больше нет. Но цифровой файл можно скопировать 100 раз. Блокчейн следит, чтобы ты не мог «скопировать» свою монету и заплатить ею сразу в двух магазинах.
🤓 Expert Deep Dive
The 'Byzantine Generals Problem' is the theoretical root of double-spending prevention. Bitcoin's Nakamoto Consensus used PoW to create a relative time-ordering of transactions. If a user tries to spend the same UTXO (Unspent Transaction Output) in two different blocks, the network only accepts the first one validated. 51% Attacks are essentially attempts to manually induce double-spending by rewriting the blockchain's history.