Protocol Architecture

CrowdProof is a hybrid on-chain/off-chain system. Computation-heavy reputation scoring runs off-chain for speed and cost efficiency, while proofs, identities, and governance live on-chain for trustlessness.

System Layers

┌─────────────────────────────────────────────────────┐
│                   Applications                       │
│        DeFi · Lending · DAOs · Marketplaces          │
├─────────────────────────────────────────────────────┤
│                    REST API                          │
│    Scores · Proofs · Identity · Compliance           │
├──────────────────┬──────────────────────────────────┤
│  Off-Chain       │           On-Chain                │
│                  │                                    │
│  Scoring Engine  │  DIDRegistry                      │
│  ML Models       │  ReputationOracle                 │
│  Data Indexers   │  CredentialVerifier                │
│  SQL Database    │  PaymentEscrow                     │
│  WebSocket Hub   │  GovernanceToken                   │
│  Webhook System  │                                    │
├──────────────────┴──────────────────────────────────┤
│              Blockchain Data Sources                 │
│     Ethereum · Polygon · Arbitrum · Optimism         │
└─────────────────────────────────────────────────────┘

Component Responsibilities

Off-Chain (Backend API)

Component	Purpose
Scoring Engine	Calculates reputation scores from on-chain activity data
Data Indexers	Monitor blockchain events and update the scoring database
SQL Database	Stores DIDs, credentials, scores, disputes, API keys
WebSocket Hub	Pushes real-time score updates to connected clients (SignalR)
Webhook System	Delivers HTTP callbacks when scores change
Compliance Module	Privacy-preserving KYC and sanctions screening

On-Chain (Smart Contracts)

Contract	Purpose
DIDRegistry	Registers and resolves Decentralized Identifiers
ReputationOracle	Stores score commitments and verifies ZK proofs
CredentialVerifier	Validates Verifiable Credentials on-chain
PaymentEscrow	Handles payments for premium API access
GovernanceToken	DAO governance for protocol parameter changes

Data Flow

1. Indexers continuously scan supported chains for DeFi, governance, and NFT activity
2. Scoring Engine processes raw activity through ML models to produce normalized 0–1000 scores
3. Scores are committed to the ReputationOracle contract as Merkle roots
4. Users query scores via the REST API or directly from the oracle contract
5. ZK Proofs allow selective disclosure (e.g., "score > 700") without revealing the actual score
6. WebSockets and Webhooks notify subscribers of score changes in real-time

Authentication Model

                    ┌──── API Key (X-API-Key header)
                    │     For: queries, batch, webhooks
Client ─────────────┤
                    │
                    └──── JWT (Bearer token)
                          For: DID updates, credentials, billing
                          Source: SIWE (Sign-In with Ethereum)

Deployment Topology

Component	Platform	Region
Backend API	Azure App Service	East US 2
Website	Azure Static Web App	Global CDN
Portal	Azure Static Web App	Global CDN
Database	Azure SQL	East US 2
Smart Contracts	EVM-compatible chains	Decentralized