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Identity System

Horizon uses an EVM-first identity system with multi-wallet support and name resolution.

Architecture​

┌─────────────────────────────────────────────────────────────┐
│                     User Identity                            │
├─────────────────────────────────────────────────────────────┤
│  Primary: EVM Address (Base L2)                             │
│  └── Missions, guilds, reputation, XP                       │
├─────────────────────────────────────────────────────────────┤
│  Linked Wallets: Additional EVM addresses                   │
│  └── Multi-wallet support with labels                       │
├─────────────────────────────────────────────────────────────┤
│  Name Resolution: Basename / ENS                            │
│  └── Human-readable names and avatars                       │
├─────────────────────────────────────────────────────────────┤
│  Off-chain: Display name, avatar, bio                       │
└─────────────────────────────────────────────────────────────┘

Wallet Integration​

CDP Embedded Wallets (Primary)​

Coinbase Developer Platform embedded wallets for seamless onboarding:

  • Email OTP - Sign up with email verification
  • Social Login - Google, Apple authentication
  • Non-custodial - Users own their keys
  • No seed phrase - Simplified UX

External Wallets​

Also supported via WalletConnect:

  • Coinbase Wallet - Native Base integration
  • MetaMask - Popular browser wallet
  • Rainbow - Mobile-first wallet
  • Other WalletConnect-compatible wallets

Authentication (SIWE)​

Horizon uses Sign-In With Ethereum (EIP-4361) for authentication:

// SIWE message format
const message = `
horizon.app wants you to sign in with your Ethereum account:
${address}

Sign in to Horizon

URI: https://horizon.app
Version: 1
Chain ID: ${chainId}
Nonce: ${nonce}
Issued At: ${issuedAt}
`;

Flow​

  1. User connects wallet
  2. Backend generates SIWE challenge with nonce
  3. User signs message with wallet
  4. Backend verifies signature
  5. JWT token issued for session

Name Resolution​

Basenames (.base.eth)​

Native Base name resolution:

// Reverse resolution: address → name
const result = await basenameService.resolveAddress('0x...');
// { name: 'alice.base.eth', avatar: 'https://...' }

// Forward resolution: name → address  
const address = await basenameService.resolveName('alice.base.eth');
// '0x...'

ENS (.eth)​

Fallback to Ethereum Name Service:

const result = await ensService.resolveAddress('0x...');
// { name: 'vitalik.eth', avatar: 'https://...' }

Priority​

  1. Check Basename first (Base-native)
  2. Fall back to ENS if no Basename
  3. Display address if neither found

Multi-Wallet Support​

Users can link multiple wallets to their account:

// Generate link message
const message = generateLinkMessage(userId, address);
// "Link wallet to Horizon\nUser: ...\nWallet: ...\nTimestamp: ..."

// User signs message
const signature = await wallet.signMessage(message);

// Backend verifies and links
await identityService.linkWallet(userId, 'evm', address, signature, message);

Wallet Management​

FeatureDescription
Primary walletMain address for missions
LabelsCustom names for wallets
UnlinkRemove linked wallets (except primary)

User Data​

On-chain (Immutable)​

  • Wallet addresses
  • Reputation attestations (EAS)
  • Achievement NFTs
  • Guild memberships

Off-chain (Mutable)​

  • Display name
  • Avatar URL
  • Bio
  • Notification preferences
  • Location history (30-day retention)

Privacy Controls​

Users can:

  • Export all data (GDPR compliance)
  • Delete off-chain data
  • Control location sharing
  • Manage notification preferences
  • Revoke linked wallets---## Future: Device AttestationPlanned for high-security operations:| Platform | Technology | |----------|------------| | Android | Play Integrity API | | iOS | DeviceCheck | | Web | WebAuthn/Passkeys |This will enable:
  • Anti-fraud protection
  • Bot prevention
  • Location verification enhancement