.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "api/gallery/structures/transactions/plot_02_replay_protection.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_api_gallery_structures_transactions_plot_02_replay_protection.py>`
        to download the full example code or to run this example in your browser via JupyterLite.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_api_gallery_structures_transactions_plot_02_replay_protection.py:


Replay protection with a chain identifier (EIP-155, 2016)
=========================================================

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's coins on both. EIP-155
added the chain id to what is signed, so a signature belongs to exactly one
network.

What to look for
----------------

A payment signed for one chain is rejected by a ledger with a different
chain id, while an account nonce still prevents replay within one chain.

The history behind this experiment: :doc:`/history/structures_breakthroughs`.

.. GENERATED FROM PYTHON SOURCE LINES 21-23

Two networks, same keys, same balances
--------------------------------------

.. GENERATED FROM PYTHON SOURCE LINES 23-44

.. code-block:: Python

    import matplotlib.pyplot as plt

    import blockchainkit as bk

    alice_key = 7
    alice_pub = bk.crypto.public_key(alice_key)
    alice = bk.structures.address(alice_pub)
    bob = bk.structures.address(bk.crypto.public_key(11))
    mainnet = bk.structures.Ledger({alice: 100}, chain_id="mainnet")
    fork = bk.structures.Ledger({alice: 100}, chain_id="classic")

    tx = bk.structures.Transaction(alice_pub, bob, 40, 0, chain_id="mainnet").signed(
        alice_key, signing_nonce=5
    )
    mainnet = mainnet.apply([tx])
    try:
        fork.apply([tx])
    except ValueError as error:
        print("Replay on the other chain rejected:", error)
    assert fork.balances[alice] == 100





.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    Replay on the other chain rejected: wrong chain ID or invalid signature




.. GENERATED FROM PYTHON SOURCE LINES 45-47

The chain id is part of the signed bytes
----------------------------------------

.. GENERATED FROM PYTHON SOURCE LINES 47-68

.. code-block:: Python

    assert b'"chain_id":"mainnet"' in tx.payload()
    results = {}
    for label, ledger in (
        ("same chain, new", bk.structures.Ledger({alice: 100}, chain_id="mainnet")),
        ("same chain, replay", mainnet),
        ("other chain", fork),
    ):
        try:
            ledger.apply([tx])
            results[label] = True
        except ValueError:
            results[label] = False
    assert results == {"same chain, new": True, "same chain, replay": False, "other chain": False}

    fig, ax = plt.subplots(figsize=(7, 3))
    ax.bar(results.keys(), [int(v) for v in results.values()], color=["#16a34a", "#dc2626", "#dc2626"])
    ax.set(
        ylabel="accepted", yticks=[0, 1], title="Nonce stops replay in time; chain id across networks"
    )
    fig.tight_layout()




.. image-sg:: /api/gallery/structures/transactions/images/sphx_glr_plot_02_replay_protection_001.png
   :alt: Nonce stops replay in time; chain id across networks
   :srcset: /api/gallery/structures/transactions/images/sphx_glr_plot_02_replay_protection_001.png
   :class: sphx-glr-single-img





.. GENERATED FROM PYTHON SOURCE LINES 69-73

Exercise
--------
Before EIP-155, how could a cautious user split their coins safely after
the fork? (Hint: make a transaction that is valid on only one chain.)


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.123 seconds)


.. _sphx_glr_download_api_gallery_structures_transactions_plot_02_replay_protection.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: lite-badge

      .. image:: images/jupyterlite_badge_logo.svg
        :target: ../../../../lite/lab/index.html?path=api/gallery/structures/transactions/plot_02_replay_protection.ipynb
        :alt: Launch JupyterLite
        :width: 150 px

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: plot_02_replay_protection.ipynb <plot_02_replay_protection.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: plot_02_replay_protection.py <plot_02_replay_protection.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: plot_02_replay_protection.zip <plot_02_replay_protection.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_