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Browser wallet for Japanese residents that lets them use their government issued ID (My Number Card) as a hardware wallet.


Created At

ETHGlobal Tokyo

Winner of


πŸŠβ€β™‚οΈ Polygon β€” Pool Prize


πŸ…°οΈπŸ…°οΈ EF β€” Best Account Abstraction


πŸ† ETHGlobal Tokyo Finalist

Project Description

The goal of Myna is to provide Japanese residents with a simple and safe browser wallet solution.

Whether you use a browser, mobile, or hardware wallet, private key management is a challenge for all web3 users across the world. Writing down your seed phrase and keeping it safe is daunting, even for the most sophisticated users. Hardware wallets are also relatively expensive with a steep learning curve, making their use unrealistic for most people, especially in Japan (which has the oldest population in the world).

As of March 2023, over 64% of Japan’s residents have an IC-chip enabled government-issued ID card (My Number Card). The Myna browser wallet enables Japanese residents to use their My Number Card like a hardware wallet, giving them a simple and safe way to self-custody their crypto and send/receive payments with just a few taps of their card.

EIP-4337 compliant contract wallets are generated for each My Number Card, abstracting away the wallet creation process for users, and enabling features such as social recovery. This will empower Japanese residents to securely transfer wallet ownership during any emergency situation.

How it's Made

We built our project on Polygon mainnet. Details below:

My Number Card:

  • The My Number Card is a NFC-type B card and it stores a RSA keypair.
  • The RSA public key can be extracted from the card by tapping the card to a NFC reader.
  • The My Number Card can sign arbitrary messages with a PIN code and return signature.

Wallet generation:

  • User taps My Number Card to NFC reader.
  • The NFC reader sends the My Number Card public key to our Browser Wallet via Web Bluetooth.
  • The browser wallet software deterministically calculates the ERC-4337 compliant contract wallet address based on My Number Card public key, even before deploying the contract wallet, and can receive payments.

Send transaction:

  • Browser requests a signature of the transaction from the contract wallet (User Operation) to My Number Card.
  • User enters PIN and taps My Number Card onto NFC reader to generate User Operation signature.
  • Browser sends User Operation and its signature to Bundler.
  • Bundler sends the transaction to execute the User Operation.
  • ERC-4337 compliant smart contract verifies the RSA signature and executes the operation.
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