Double spending
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How to avoid double spending ?
Transcript of Double spending
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How to avoid double spending ?
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Problem
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Order problem
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We cannot depend on time as it is easily
falsifiable.
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Double spend fraud
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Invalidated by some nodes.
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How to agree on an order ?
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Blockchain.
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Transaction chain
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Block
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Answer to a specific problem
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First person to find a solution will broadcast the block to the
network
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Several possible branches
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You need cpu power to have your block broadcasted
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You always switched to the longuest branch.
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Half of nodes must be honnest.
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I have constructed this presentation based on :· Bitcoin under the hood
· Mastering Bitcoin· Original paper
· Coursera
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