Celo Tech Talks Part 13 - Feeless Onboarding


Judy Piper, an engineer at Sea Labs and the host of the Celo Tech Talk series, welcomes everyone to the session. The talk aims to share Celo technology knowledge with the growing Celo community. In the previous talks, they provided an overview of Celo’s full-stack architecture and design.

Speaker Introduction

Bogdan, a protocol engineer at Sea Labs, focuses on the Celo Economic Circle in Berlin. He highlights the importance of creating a financial system that is easy to use and inclusive. To achieve this, Sea Labs has developed Valora, a mobile-first wallet and payments app. The onboarding process for Valora involves linking a phone number to the user’s account through an attestation protocol.

Onboarding with Attestation

To link a phone number to a Celo address, the user interacts with a smart contract and communicates with the validators’ attestation service. The process involves obtaining signatures in an SMS, validating them, and sending them to the Celo chain. This process incurs a cost, as it aligns with the economic incentives of the decentralized network.

Addressing the Cost Issue

Sea Labs aims to help users onboard to Valora by subsidizing the gas fees associated with attestations. They explore the concept of meta transactions as a solution to subsidize gas fees. Meta transactions allow the payment of fees on behalf of the user. This approach simplifies the process and reduces complexity in the protocol.

Introducing Smart Contract Wallets

Smart contract wallets play a crucial role in implementing meta transactions. They act as intermediaries between the user and the attestation contract. Bogdan explains how a smart contract wallet can represent the user and execute the logic of the attestation contract. By using smart contract wallets, users can avoid directly paying gas fees for transactions.

Leveraging Relayers and Meta Transactions

Relayers facilitate the execution of meta transactions by interacting with smart contract wallets and the Celo chain. They handle the transfer of funds from the user’s account to the smart contract wallet, ensuring the wallet has the necessary funds for gas fees. Multiple relayers in different regions contribute to network resilience.

Centralization and Future Plans

To balance user experience and security, Sea Labs has a service managing funds outside the internet. This centralized aspect allows for better security measures. While the current implementation is centralized, Sea Labs intends to explore ways to expand usage and potentially decentralize the system.

Results and Conclusion

Sea Labs successfully deployed around 1,000 smart contract wallets, executed thousands of meta transactions, and onboarded approximately 1,000 users to Valora using the new feeless version. The talk concludes with a Q&A session, addressing questions about cost, validators, user vouching, and deployment of user proxy smart contracts.