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Introduction to Ordinals and SADO Protocol

Introduction to Ordinals and SADO Protocol

Introducing Ordinals at FOSSASIA Summit 2023 in Singapore on 13 April 2023.

Also introducing SADO Protocol. The first protocol allowing decentralized and trustless trading of Ordinals. SADO is Self-Authenticating Decentralized Ordinalbook.

U-Zyn Chua

April 17, 2023

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  1. U-Zyn Chua · Birthday Research

    & SADO Protocol
    FOSSASIA Summit 2023

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  2. Hi, I'm U-Zyn Chua
    • CTO & Co-Founder of Cake DeFi

    • In Bitcoin since 2010.

    • Active in the Bitcoin, Ethereum and Dash

    • Chief architect of Sand Dollar

    - The world's
    rst retail CBDC for Bahamas.

    • Presented in FOSSASIA 2016.

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  3. Let's talk about

    Bitcoin Ordinals

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  4. What are Bitcoin Ordinals?

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  5. Ordering of satoshis
    1st satoshi to 21e(6 + 8)th satoshi

    21 quadrillion

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  6. Ordering of satoshis
    It's arbitrary, but let's

    set a rule:

    First-in First-out


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  7. Bitcoin Ordinals
    • It's a digital artifact.

    • Non-fungibility.

    • Why is it not NFT?

    • Content is fully on-chain

    • No external link

    • Immutable

    • Ethereum NFT (ERC 721) often does not contain
    any actual artifact.

    • Inscription is an added feature.

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  8. Inscriptions
    • Further feature to make Ordinals more

    • Ordinal (satoshi) can be inscribed with data,
    commonly image.

    • Any binaries are

    • Text, audio, image, movie.

    • Theoretical max size: 4MB.

    • Fully on-chain.

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  9. How?
    • Encoding of data (plain/binary) into Bitcoin witness space via Taproot.

    • Includes MIME type


    OP_PUSH "ord"


    OP_PUSH "text/plain;charset=utf-8"


    OP_PUSH "Hello, world!"


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  10. Trading &

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  11. Trading
    • Trading (exchanging) of a speci
    c satoshis, for more satoshis.

    • Exchanging of Ordinals (non-fungible) with Cardinals (fungible).

    • The beauty of UTXO model of Bitcoin allows it to happen trustlessly.

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  12. Trading
    1. Either buyer or seller (usu. buyer) can craft a partially signed transaction.

    2. Transmits the partially signed tx to the other party.

    3. Agreeable, complete the signature.

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  13. Marketplace
    • Problem: How do seller or buyer make the intent known?

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  14. SADO Protocol

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  15. SADO
    Self-Authenticating Decentralized Ordinalbook

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  16. SADO
    Self-Authenticating Decentralized Ordinalbook
    • Free & open source.

    • Self authenticating: all signatures are validated.

    • Has a default global order book.

    • Also supports alternative order book, allowing other SADO users to operate
    their own private order book if required.

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  17. Ordzaar
    Decentralized Ordinals Bazaar

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  18. • Utilizes SADO Protocol.

    • Non-custodial. You own your Bitcoin, Ordinals and Cardinals.

    • UX Challenges:

    • Bitcoin ecosystem is not DAPP-ready.

    • No de facto wallet.

    • Ordinals support are still limited on Bitcoin wallets.

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  19. Thank you.
    U-Zyn Chua


    Reach me at
    Learn more about Birthday Research at https://birthday.dev
    Learn more about SADO Protocol at https://sado.space

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