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I have a local Bitcoin-QT wallet. Can transaction malleability be used to steal my horde of tens of thousands of Satoshis?

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No. It can not under any circumstances be used to steal funds from a Bitcoin-QT wallet.

  • 2
    It would be nice to have a full explanation instead of just the word "no" – bitfreak Feb 27 '14 at 4:26
  • There's plenty of information about what "transaction malleability" is and what it affects. Should I write an explanation why lawnmower mufflers can't be responsible for stealing funds from a wallet too? It's about the same level of connection and coherence. – user13413 Feb 27 '14 at 4:35
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    If it is patently obvious and no one would ever have the doubt why did the asker asked his question in the first place? Any question that its worth asking its worth answering with more than the word no. – bitfreak Feb 27 '14 at 5:00
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Transaction malleability has a very small effect on a regular user, at most it can mess up some of your bookkeeping if you store the Transaction Id of a transaction before it is confirmed.

Transaction malleability only affects unconfirmed transactions. The bug allows an unconfirmed transaction to be duplicated with a new transaction id. Since the two (or more) transactions are spending the same input only one can go through, but that one of them should deliver the money just as expected. For major services that rely on a big number of unconfirmed transactions, this can cause some headache, but there is no way it could be used to steal money from your Bitcoin-Qt wallet.

  • When you say transaction malleability only affects unconfirmed transactions, do you mean that as long as there is one confirmation, transaction malleability cannot occur? – Pacerier May 22 '14 at 17:29
  • Correct. Essentially it is a "double spend" with the same outputs. The "double spend" only differs by having a different transaction ID. When your transaction has already made it into a block, it is immune to transaction malleability, as the inputs are already used up. – Murch May 22 '14 at 20:48

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