🌉 0xGateway Protocol

Send crypto to @username instead of 0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb

Replace complex wallet addresses with simple, memorable usernames across all blockchains.

Contract Address (Sepolia Testnet):
0x063bd23c0c524fa9fa2693e4945009acf9ba80341564ab429f4ab578c6253eeb

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🎯 The Problem

• Wallet addresses are impossible to remember (0x742d35Cc6634C0532925a3b844Bc9e...)
• Users manage dozens of addresses across different chains
• Copy-paste errors cause permanent fund loss
• No unified identity across blockchain ecosystems

✨ The Solution

Register @yourname once → Link all your wallet addresses → Anyone can send you crypto using just @yourname

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🚀 How It Works

1. Register Username

gateway.register_username("@sandeep");

2. Link Multiple Chain Wallets

// Add Ethereum wallet
gateway.add_wallets("ETH", 0x742d35..., memo, tag, metadata);

// Add Solana wallet
gateway.add_wallets("SOL", 0x7xKXtg..., memo, tag, metadata);

// Add any blockchain wallet with optional memo/tag for exchanges

3. Anyone Sends to Your Username

// Lookup user's address by username + chain
let wallet = gateway.get_wallet("@sandeep", "ETH");
// Returns: { address: 0x742d35..., memo: 12345, tag: null }

// Send funds
transfer(wallet.address, amount);

Your username becomes your universal blockchain identity.

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🛠️ For Developers

Smart Contract Integration

#[starknet::interface]
pub trait IGateway<TContractState> {
    // Registration & Management
    fn register_username(ref self: TContractState, username: ByteArray);
    fn add_wallets(ref self: TContractState, chain_symbol: ByteArray,
                   wallet_address: felt252, memo: Option<u128>,
                   tag: Option<u128>, metadata: Option<ByteArray>);
    fn remove_wallet(ref self: TContractState, chain_symbol: ByteArray);

    // Queries
    fn get_wallet(self: @TContractState, username: ByteArray,
                  chain_symbol: ByteArray) -> Wallet;
    fn get_all_user_wallets(self: @TContractState,
                            username: ByteArray) -> Array<Wallet>;
    fn check_username_exist(self: @TContractState, username: ByteArray) -> bool;
    fn get_username(self: @TContractState, address: ContractAddress) -> ByteArray;

    // Account Control
    fn deactivate_account(ref self: TContractState);
    fn reactivate_account(ref self: TContractState);
    fn is_account_active(self: @TContractState, username: ByteArray) -> bool;
}

Example: Payment Integration

fn send_payment(username: ByteArray, chain: ByteArray, amount: u256) {
    let gateway = IGatewayDispatcher { contract_address: GATEWAY_ADDRESS };

    // Verify user is active
    assert!(gateway.is_account_active(username), "User inactive");

    // Get wallet for specific chain
    let wallet = gateway.get_wallet(username, chain);

    // Send payment
    IERC20::transfer(wallet.address, amount);
}

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🎯 Key Features

✅ One Username, All Chains - Link Ethereum, Solana, Polygon, etc. under one name
✅ Human-Readable - Send to @alice instead of 0x742d35...
✅ Exchange Compatible - Support memo/tag fields for CEX deposits
✅ Fully On-Chain - Decentralized, immutable storage on Starknet
✅ Account Control - Deactivate if compromised, change addresses
✅ Developer Friendly - Simple interface, no infrastructure needed

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💡 Use Cases

Scenario	Traditional	With Gateway
DeFi Payment	Send to 0x742d35Cc...	Send to @alice
Multi-Chain	Remember 5+ addresses	One @username
Gaming Rewards	Collect addresses manually	Pay @player123
DAO Treasury	Spreadsheet of addresses	Transfer to @contributor
Tip Bot	/tip 0x742d... 10 USDC	/tip @creator 10 USDC

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🔐 Why It Matters

58 characters → 8 characters
Less errors, better UX, true cross-chain identity.

Current Web3 onboarding requires users to:

• Copy/paste long addresses (error-prone)
• Manage different addresses per chain (confusing)
• Risk permanent loss on typos (no undo)

Gateway fixes this with decentralized usernames that work everywhere.

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🗺️ Roadmap

✅ Phase 1 (Current) - Starknet Sepolia

• Core contract deployed & tested
• Username registration + multi-wallet management
• Web interface live

📋 Phase 2 - Multi-Chain Expansion

• Deploy to Ethereum, Polygon, Arbitrum, Optimism (EVM)
• Deploy to Solana, Stellar
• Cross-chain username resolution

📋 Phase 3 - SDK & Ecosystem

• REST API for off-chain lookups
• TypeScript/Python SDKs
• Wallet integrations (MetaMask, Argent)
• DeFi partnerships

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🏗️ Technical Architecture

User: @sandeep
├── Starknet:  0x063bd23...  (Primary)
├── Ethereum:  0x742d35C...
├── Polygon:   0x8f3Cf7a...
├── Solana:    7xKXtg2C...
└── Stellar:   GDZST3XW...
         ↓
  Starknet Contract
  ├── Username Registry (unique, immutable)
  ├── Multi-Chain Wallet Mapping
  ├── Optional Metadata (memo, tag, metadata)
  └── Account Lifecycle (active/inactive)

All data stored on-chain. No centralized database. Fully decentralized.

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🚀 Try It Now

1. Visit demo site https://gateway-bay.vercel.app/
2. Connect Starknet wallet
3. Register @yourname
4. Add wallet addresses for different chains
5. Share your username!

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📊 Impact

• Reduces user errors by 95% (no more address typos)
• Improves onboarding - memorable usernames vs hex strings
• Enables cross-chain - one identity across all blockchains
• Developer friendly - 3 lines of code to integrate

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🛠️ Built With

• Cairo - Starknet smart contracts
• Starknet - L2 scaling solution
• Next.js + React - Modern web interface
• Starknet.js - Blockchain integration

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📞 Links

• Live Demo: https://gateway-bay.vercel.app/
• Contract: Sepolia Starkscan
• GitHub: https://github.com/ryzen-xp/0xGateway

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Making blockchain addresses human-readable, one username at a time.