.. _sphx_glr_api_gallery_structures_transactions:

Transaction identity
--------------------

What a transaction id covers, and which network a signature belongs to.


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    <div class="sphx-glr-thumbcontainer" tooltip="Bitcoin&#x27;s transaction id hashed the whole transaction, signatures included. Anyone relaying a transaction could alter its signature encoding without invalidating it, changing the id. In 2014 the Mt. Gox exchange blamed malleability for lost withdrawals; Decker and Wattenhofer found it explained only a small fraction. Segregated witness (2017) moved signatures out of the id, which also made payment channels such as Lightning safe to build.">

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  .. image:: /api/gallery/structures/transactions/images/thumb/sphx_glr_plot_01_malleability_thumb.png
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  :doc:`/api/gallery/structures/transactions/plot_01_malleability`

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      <div class="sphx-glr-thumbnail-title">Transaction malleability and segregated witness (2014-2017)</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="In 2016 Ethereum split into two chains, Ethereum and Ethereum Classic, with the same accounts and keys. A transaction signed for one was valid on the other: anyone could replay it, moving the sender&#x27;s coins on both. EIP-155 added the chain id to what is signed, so a signature belongs to exactly one network.">

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  .. image:: /api/gallery/structures/transactions/images/thumb/sphx_glr_plot_02_replay_protection_thumb.png
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  :doc:`/api/gallery/structures/transactions/plot_02_replay_protection`

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      <div class="sphx-glr-thumbnail-title">Replay protection with a chain identifier (EIP-155, 2016)</div>
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.. toctree::
   :hidden:

   /api/gallery/structures/transactions/plot_01_malleability
   /api/gallery/structures/transactions/plot_02_replay_protection