Upgrade to Pro — share decks privately, control downloads, hide ads and more …

Looking back at EDCON 2019 - blockchain.tokyo#19

Looking back at EDCON 2019 - blockchain.tokyo#19

Shun Takagiwa

May 24, 2019
Tweet

More Decks by Shun Takagiwa

Other Decks in Technology

Transcript

  1. Looking back at EDCON 2019
    Shun Takagiwa
    Senior Software Architect at LayerX Inc.
    blockchain.tokyo #19

    View full-size slide

  2. about me
    Shun Takagiwa / 高際 隼
    Senior Software Architect at LayerX Inc.
    ● Software developer using blockchain (2018-)
    ● former smartphone games developer (2013-2018)
    ● studied mathematics & computer science
    at Tokyo Tech (2007-2013)
    currently responsible for a product development
    to securitize real estate using blockchain technology
    @shun_tak

    View full-size slide

  3. Table of contents
    1. Participated in EDCON!!!!
    a. What is EDCON?
    b. at the hackathon (April 8-10)
    c. in the main hall (April 11-13)
    2. ZEXE on Plasma (my team’s product at the hackathon)

    View full-size slide

  4. Participated in EDCON!!!!
    Sydney

    View full-size slide

  5. What is EDCON?
    Community Ethereum Development Conference
    ● annual global Ethereum conference
    ○ aiming to boost the communication and interaction of Ethereum communities worldwide
    and to accelerate the sound development of Ethereum ecosystem
    ● EDCON2019 in 8-13 April in Sydney (6 days)
    ○ 3-day hackathon
    ○ 3-day conference
    ● EDCON2018 in Toronto (3 days)
    ● EDCON2017 in Paris (2 days)

    View full-size slide

  6. at the hackathon
    2 teams participated from LayerX
    you can see all 18 teams here: https://edcon-hack.devpost.com/submissions
    ● ZEXE on Plasma (my team)
    ○ Scaling decentralized arbitrary computation with zk-SNARKs
    ● CBC Casper Validator Rotation (colleagues’s team)
    ○ A proposal of the protocol of validator rotation in CBC Casper
    and the implementation of a simulator & visualizer to do experiments
    Hachathon topics
    ● Layer 1: Sharding/PoS/Clients
    ● Layer 2: Plasma/Channel/Snark

    View full-size slide

  7. CBC Casper visualization

    View full-size slide

  8. ENS Prize Winners (including my team :)

    View full-size slide

  9. in the main hall

    View full-size slide

  10. in the main hall

    View full-size slide

  11. in the main hall
    2 speakers participated from LayerX
    Ryuya Nakamura
    Formal Verification and CBC Casper
    https://www.youtube.com/watch?v=XUguMReOXek
    Dominik Harz
    XCLAIM: Trustless, Interoperable,
    Cryptocurrency-Backed Assets
    The video hasn’t been uploaded on YouTube yet

    View full-size slide

  12. ZEXE on Plasma
    Scaling decentralized arbitrary computation
    with zk-SNARKs

    View full-size slide

  13. Background
    Scalability with Plasma
    e.g. MVP, Generalized Plasma
    Privacy with zk-SNARKS
    e.g. ZoKrates, Zcash, ZEXE
    Why not both? Let’s build ZEXE on Plasma!

    View full-size slide

  14. ZEXE is generalized
    - UTXO model (original paper)
    - Privacy-preserving smart contracts
    - Arbitrary contract functions
    - Arbitrary data in contracts
    - Succinct proofs with zk-SNARKS
    Our use case: ERC20 contracts in zero knowledge

    View full-size slide

  15. ZEXE Overview
    https://eprint.iacr.org/2018/962.pdf
    Public: Serial numbers, commitments, memo,
    ledger digest, zk proof, predicates
    Private: address public key, address secret key,
    data payload

    View full-size slide

  16. ZEXE on Plasma
    https://eprint.iacr.org/2018/962.pdf
    Plasma
    Smart contract
    on Ethereum
    Public: Serial numbers, commitments, memo,
    ledger digest, zk proof, predicates
    Private: address public key, address secret key,
    data payload
    IPFS

    View full-size slide

  17. System components of ZEXE on Plasma
    Merkle
    root 1
    Merkle
    root 2
    Merkle
    root 3
    Merkle
    root 1
    tx1
    Merkle
    root 2
    tx2
    Merkle
    root 3
    tx3
    Private
    inputs 1
    Private
    inputs 2
    Private
    inputs 3
    Front-end
    Secret sharing
    zk-Plasma
    Root chain
    Generate
    transaction
    Execute
    zk-proving
    Mint coin
    Transfer
    coin

    View full-size slide

  18. Workflow
    1. Generate a transaction and a zk-proof on local
    2. Store secret data on IPFS to share with a counterparty
    3. Send the transaction on Plasma
    4. Execute a smart contract to update merkle root
    Team
    Yohei Oka, Quantstamp
    Web3, Smart contract, ENS
    Shun Takagiwa, LayerX
    IPFS, Data sharing
    Dominik Harz, LayerX
    Plasma, Smart contract
    Osuke Sudo, LayerX
    zk-SNARKs, Transaction

    View full-size slide

  19. Transaction generation with Rust
    Private data is uploaded
    to IPFS in this process
    Uploaded data ⇒

    View full-size slide

  20. Now Hiring!!!!
    Web系や金融系の経験がある方、ぜひ一緒に新しいサービスを作りませんか?
    参考:LayerXの事業紹介とカルチャー
       ⇒https://link.medium.com/Ftg6zkkMWW

    View full-size slide

  21. What we built
    ● Privacy-preserving transaction to mint tokens
    ● Private data sharing using IPFS
    ● Plasma smart contract and off-chain contract
    ○ to prevent double spending
    ○ to maintain merkle tree of commitment records
    ● Transaction execution on plasma
    ● Web UI
    ● ENS

    View full-size slide

  22. What works
    ● Minting transactions
    ● Sending transactions
    ● Sharing a secret on IPFS
    ● Storing Merkle headers to Ethereum
    ● Storing Merkle tree and transaction verification on the Plasma child chain

    View full-size slide

  23. Things that were challenging
    ● ZEXE uses a different curve than Ethereum supports
    ● ZEXE has no concept of blocks
    ● Transaction model of ZEXE is different to Plasma MVP UTXO

    View full-size slide

  24. Next steps
    ● Make elliptic curve be compatible with Ethereum
    ○ From BLS12-381 to BN256
    ● Verify zk-SNARKS
    ● Encrypt data on IPFS with a recipient’s public key
    ● Make it optional to use IPFS for data exchange
    (enable to use e-mail, temporary shared storage, etc)
    ● Add more functionalities
    ○ e.g. ERC20, DEX, stable coin
    ● Allow exit in Plasma contract

    View full-size slide

  25. Background - Private computation
    ● ZEXE’s Goal: A ledger-based system in which transactions attest to offline
    computations while simultaneously providing privacy and succinctness
    ● Zerocash
    ○ Money is represented via coins
    ○ Commitment of a coin is published on the ledger when the coin is created
    ○ Serial number of the coin is published when the coin is consumed
    ○ A zero knowledge proof attesting
    that the serial numbers belong to coins created in the past without identifying which ones
    ○ Commitments contain new coins of the same total value
    ○ A transaction is private which contains how many coins were consumed and created
    (each coin’s value and owner address remain hidden)
    ● ZEXE: Extending to an arbitrary function
    ○ The function is known in advance to everyone
    ○ Think of a coin as a record that stores some arbitrary data (payload) rather than integer

    View full-size slide