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Scratch-off, disposable prepaid crypto cards for bankless onboarding


Created At

ETHGlobal Lisbon

Winner of


🔐 Gnosis Chain — Best on Safe


🥈 Safe — Best Use


🏊 Scroll — Deploy a Smart Contract


🥇 Nouns DAO — Best Public Infrastructure

Project Description

Context & Problem The last few weeks Bolivia has been suffering a bankrun on US dollars, because the country's reserves are plummeting. Despite crypto being forbidden in Bolivia, people are finding refuge for their wealth in crypto through Binance P2P - at the cost of a big premium on the exchange rate. This has already happened a few years ago in Venezuela and Argentina, where a few days ago the Central Bank also forbid buy and sell of crypto through Payment Providers.

Our solution Scratch-off, disposable prepaid crypto cards. They act as a crypto gift-card that anybody can create and sell. After being activated by the merchant, the buyer can use the card as a direct on-ramp to crypto in a privacy preserving way, without prior knowledge in crypto/wallets and with a familiar UX (people in Bolivia use these scratch-off cards on a daily basis to top-up their phone balances).

Goals and challenges The concept of prepaid, disposable crypto cards is not new - however security and UX is enhanced with account abstraction. The main goal of this hack is to bring awareness to this urgent situation. We believe this could be a great opportunity to work together as an industry to provide Bolivians with an exit to a path of wealth destruction and poverty, and that way show a real world example of how situations like Venezuela and Argentina could be avoided This being said, we are aware of the risks and challenges this idea poses:

  • Liquidity risk of the crypto provider for the cards
  • Merchant risk of getting exposure to
  • Uncertain regulatory environment

How it's Made

For user log-in and account creation we used web3auth. The prepaid cards are a Smart Account under the hood. We used Account Abstraction from Safe with a custom logic for the activation of the cards using Guards. For each card we are creating a Safe from a custom contract that has a Guard enabled by default. We also used Safe {Core} SDK, the Relay Kit to enable transactions with Gelato. Documentation for the SyncFeeCalls were faulty: examples were too simple, so we had to figure out ourselves how to properly encode Safe function calls. The Account Abstraction Kit also didn't work with Safe management transactions, like moving ownership from one address to the other.

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