Kage

Introduction

Hey everyone, super excited to show you what we've been working on—Kage-Pay. "Kage" is Japanese for shadow, so think of Kage-Pay as your ninja move in the blockchain universe!

In today's blockchain world, we've noticed something big: the amount of assets out there is huge, but we're still missing a safe and easy way to pay someone face-to-face. This is gonna be a huge roadblock for trading assets easily and for blockchain to really take off everywhere.

When it comes to paying someone in person, people are worried about accidentally showing off how much they've got in their blockchain wallets. It kinda kills the vibe for using blockchain to pay for stuff. Plus, there's always that nagging worry about having enough gas fees for transactions, the crazy ups and downs of coin prices, and the headache of juggling several wallets at once.

Kage-Pay solves the above problems through the following four technologies:

• Stealth Address
• UTXO Mode
• Token Paymaster
• Cross-Chain Transfer Protocol

Stealth Address : we generate a set of dual-keys on the user's mobile device and protect these keys using the device's own security mechanisms (such as keychain). Users only need to scan a QR code to obtain someone else's public key and generate a one-time address for the recipient. Through this mechanism, we can protect the privacy of your personal assets.

UTXO Mode: Users' one-time addresses scattered across various locations are utilized during a transaction. We employ a mechanism similar to UTXO, allowing users to calculate the exact amount needed for the transaction from multiple wallets and transfer it to the recipient in one go.

Token Paymaster: To ensure the smoothest user experience, each time a user receives payment, we facilitate this using an ERC4337 contract wallet. Thus, when they wish to make a transfer, it can be done through Paymaster, allowing the use of USDC exclusively for gas fees. This approach minimizes the user's need to worry about gas fees across all wallets.

Cross-Chain Transfer Protocol: Besides gas fees, cross-chain transactions are among the most challenging aspects of blockchain for the average user. To address this, we utilize the Circle-provided CCTP (Cross-Chain Transfer Protocol), which enables one-click cross-chain transactions within KagePay, effectively solving the cross-chain dilemma.

How Kage-Pay Works:

• KagePay App: This little wizard on your phone lets you handle all those sneaky stealth addresses and uses UTXO magic to make sending stuff simpler. Plus, we're all about those contract wallets, so you can tap into the Paymaster feature. This cool trick lets you pay for gas with USDC. No more crypto headaches!
• KagePay Store Web: Picture this as your go-to spot online for all things merchant payments. Merchants just send over a Viewing Key, and bam, they've got their own sleek payment page on the site. It's like flipping a switch to get blockchain payments rolling in.

Kage-Pay isn’t just some tool; it’s the solution we’ve all been waiting for when it comes to paying with blockchain in real life. By bringing in a way to pay that’s both safe and easy to use, we’re tackling those pesky privacy leaks head-on. But it’s more than that – we’re also unlocking new doors for how freely and easily blockchain assets can move around. We’re betting big on Kage-Pay to really change the game, making sure everyone can get in on the blockchain action without stressing out.

Github

https://github.com/a00012025/kage-pay

It's entirely built within the period of ETH Taipie Hackathon 2024!

Demo Site

Receiver Site: https://kage-pay.vercel.app/

Sender App: 

- Android apk: https://drive.google.com/file/d/187DWf65ClkjGXwku7CrXmKt4qcXfK4_h/view?usp=drive_link

- iOS ipa: https://drive.google.com/file/d/1I4nKJNq1IdNy3-21NpEMlZSZBcWWWLvo/view?usp=drive_link

Team

Harry Chen - Team lead guiding us on chain and off chain. Telegram: @a00012025
Charles Chien - Build beautiful app and do the math & stuff
Dorara Hsieh - Build beautiful app and do the math & stuff
Beans Hung - Write & Deploy some contracts on some chains
Arron Su - Build beautiful website and do the math & stuff

Bounties

Circle

1. Cross Border Payments is one of our main scenario!

2. Thanks to Cross-Chain Transfer Protocol, we make cross-chain stablecoin aggregation a lot easier!

Linea

Our smart contracts are deployed on Linea! (address in our repo's README)

ETHTaipei Community Finalist

We'll share and demo our application on ETHTaipei stage!

Optimism

Our innovative payment application is on optimism sepolia! (contract address in our repo's README)

Polygon

Our application utilizes Dual-Key Stealth Addresses as our core concept to enhance privacy.

Scroll

Our application is on scroll sepolia! (contract address in our repo's README)

Zircuit

Our application is on zircuit! (contract address in our repo's README)