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(note: this is a temporary file, to be added-to by anybody, and moved to
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release-notes at release time)
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New RPC methods
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===============
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Fee/Priority estimation
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-----------------------
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estimatefee nblocks : Returns approximate fee-per-1,000-bytes needed for
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a transaction to be confirmed within nblocks. Returns -1 if not enough
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transactions have been observed to compute a good estimate.
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estimatepriority nblocks : Returns approximate priority needed for
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a zero-fee transaction to confirm within nblocks. Returns -1 if not
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enough free transactions have been observed to compute a good
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estimate.
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Statistics used to estimate fees and priorities are saved in the
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data directory in the 'fee_estimates.dat' file just before
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program shutdown, and are read in at startup.
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Double-Spend Relay and Alerts
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=============================
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VERY IMPORTANT: *It has never been safe, and remains unsafe, to rely*
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*on unconfirmed transactions.*
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Relay
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-----
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When an attempt is seen on the network to spend the same unspent funds
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more than once, it is no longer ignored. Instead, it is broadcast, to
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serve as an alert. This broadcast is subject to protections against
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denial-of-service attacks.
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Wallets and other bitcoin services should alert their users to
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double-spends that affect them. Merchants and other users may have
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enough time to withhold goods or services when payment becomes
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uncertain, until confirmation.
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Bitcoin Core Wallet Alerts
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--------------------------
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The Bitcoin Core wallet now makes respend attempts visible in several
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ways.
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If you are online, and a respend affecting one of your wallet
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transactions is seen, a notification is immediately issued to the
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command registered with `-respendnotify=<cmd>`. Additionally, if
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using the GUI:
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- An alert box is immediately displayed.
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- The affected wallet transaction is highlighted in red until it is
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confirmed (and it may never be confirmed).
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A `respendsobserved` array is added to `gettransaction`, `listtransactions`,
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and `listsinceblock` RPC results.
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Warning
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-------
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*If you rely on an unconfirmed transaction, these change do VERY*
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*LITTLE to protect you from a malicious double-spend, because:*
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- You may learn about the respend too late to avoid doing whatever
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you were being paid for
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- Using other relay rules, a double-spender can craft his crime to
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resist broadcast
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- Miners can choose which conflicting spend to confirm, and some
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miners may not confirm the first acceptable spend they see
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