.. _sphx_glr_api_gallery_channels_interoperability:

Interoperability
----------------

Moving value between chains: atomic swaps, light-client relays, and bridges that trust a committee.


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  <div id='sg-tag-list' class='sphx-glr-tag-list'></div>


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    <div class="sphx-glr-thumbnails">

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    <div class="sphx-glr-thumbcontainer" tooltip="Alice has coins on chain A, Bob on chain B, and neither will pay first. Tier Nolan&#x27;s protocol ties both payments to one secret. Alice locks her coins to Bob behind the hash of a secret, refundable to her at T_A; Bob locks his to Alice behind the same hash, refundable at T_B. Alice claims on B by revealing the secret, and Bob reads it there and claims on A. The swap is atomic if">

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  .. image:: /api/gallery/channels/interoperability/images/thumb/sphx_glr_plot_01_atomic_swaps_thumb.png
    :alt:

  :doc:`/api/gallery/channels/interoperability/plot_01_atomic_swaps`

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      <div class="sphx-glr-thumbnail-title">Tier Nolan's atomic cross-chain swaps (2013)</div>
    </div>


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    <div class="sphx-glr-thumbcontainer" tooltip="An Ethereum contract cannot see Bitcoin. BTC Relay let it check Bitcoin payments the way a light client does: relayers submit block headers, the contract checks that each links to a stored one and meets its proof-of-work target, and it follows the chain with the most work. A contract can then verify that a transaction is in a block of that chain under c confirmations, with a Merkle proof against the header&#x27;s root. Each header adds expected work">

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  .. image:: /api/gallery/channels/interoperability/images/thumb/sphx_glr_plot_02_btc_relay_thumb.png
    :alt:

  :doc:`/api/gallery/channels/interoperability/plot_02_btc_relay`

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      <div class="sphx-glr-thumbnail-title">BTC Relay: a Bitcoin light client in an Ethereum contract (2016)</div>
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    <div class="sphx-glr-thumbcontainer" tooltip="Most bridges do not verify the other chain; they trust a committee to sign withdrawals, and are exactly as safe as its keys and the code that checks its signatures. In 2022 both failed. Ronin released funds on 5 of 9 validator signatures; one company ran four validators and still held permission to sign for a fifth, so a single breach yielded 173,600 ether and 25.5 million USDC. Wormhole&#x27;s Solana program trusted an account, supplied by the caller, saying that the guardians&#x27; signatures had been checked; a forged account minted 120,000 wrapped ether from nothing.">

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  .. image:: /api/gallery/channels/interoperability/images/thumb/sphx_glr_plot_03_bridge_exploits_thumb.png
    :alt:

  :doc:`/api/gallery/channels/interoperability/plot_03_bridge_exploits`

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      <div class="sphx-glr-thumbnail-title">Bridge failures: the Ronin and Wormhole exploits (2022)</div>
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    </div>


.. toctree::
   :hidden:

   /api/gallery/channels/interoperability/plot_01_atomic_swaps
   /api/gallery/channels/interoperability/plot_02_btc_relay
   /api/gallery/channels/interoperability/plot_03_bridge_exploits