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Overview

CreditNexus provides blockchain-based notarization for documents and deals using smart contracts on the Base network. This enables immutable, multi-party signing with MetaMask integration and x402 payment processing. Code Reference: app/services/notarization_service.py, app/api/remote_routes.py, contracts/SecuritizationNotarization.sol
Frontend: client/src/components/NotarizationModal.tsx

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Key Features

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Multi-Party Signing

  • Required Signers: Define multiple required signers
  • MetaMask Integration: Each signer signs with their MetaMask wallet
  • Signature Verification: Ethereum signature verification
  • Completion Tracking: Track signing progress
Code Reference: app/api/remote_routes.py (notarization endpoints)

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Smart Contract Integration

  • SecuritizationNotarization Contract: Smart contract on Base network
  • Immutable Records: Blockchain-based transaction records
  • Event Emission: Smart contract events for notarization
  • Hash Verification: CDM payload hash verification
Code Reference: contracts/SecuritizationNotarization.sol

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x402 Payment Integration

  • Notarization Fees: Optional payment for notarization services
  • USDC Payments: Payments in USDC stablecoin
  • Payment Skipping: Admin users can skip payment requirement
  • Payment Status: Track payment completion
Code Reference: app/services/x402_payment_service.py, client/src/components/NotarizationPayment.tsx

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Workflow

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1. Create Notarization Request

  1. Select Document/Deal: Choose document or deal to notarize
  2. Add Signers: Add required signer wallet addresses
  3. Configure Message: Set custom message prefix
  4. Create Request: Generate notarization record
  5. Payment: Process x402 payment (if required)

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2. Sign Notarization

  1. Get Nonce: Retrieve signing nonce for wallet address
  2. Sign Message: Sign message with MetaMask
  3. Submit Signature: Submit signature to API
  4. Verification: System verifies Ethereum signature
  5. Completion: Check if all signers have signed

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3. Complete Notarization

  1. All Signatures: All required signers have signed
  2. Blockchain Submission: Submit to smart contract (if enabled)
  3. CDM Event: Generate CDM notarization event
  4. Status Update: Update notarization status to “signed”

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API Endpoints

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Create Notarization

Create a notarization request for a deal. Request Body: 
{
  "required_signers": ["0x...", "0x..."],
  "message_prefix": "CreditNexus Notarization",
  "auto_hydrate_deal": true,
  "skip_payment": false
}
Response (402 Payment Required): 
{
  "status_code": 402,
  "status": "Payment Required",
  "notarization_id": 123,
  "payment_request": {...}
}
Code Reference: app/api/remote_routes.py

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Get Notarization Nonce

Get signing nonce for a wallet address. Query Parameters:
  • wallet_address: Wallet address to get nonce for
Response: 
{
  "message": "CreditNexus Notarization\nNonce: 12345\n...",
  "nonce": "12345",
  "notarization_hash": "0x..."
}

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Sign Notarization

Sign a notarization with MetaMask signature. Request Body: 
{
  "wallet_address": "0x...",
  "signature": "0x...",
  "message": "CreditNexus Notarization\n..."
}
Response: 
{
  "status": "success",
  "notarization_status": "signed",
  "signatures_count": 2,
  "signers_remaining": 0
}

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Smart Contract

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SecuritizationNotarization Contract

Location: contracts/SecuritizationNotarization.sol Functions:
  • createNotarization(): Create new notarization request
  • addSignature(): Add signature to notarization
  • completeNotarization(): Complete notarization when all signers have signed
Events:
  • NotarizationCreated: Emitted when notarization is created
  • SignatureAdded: Emitted when signature is added
  • NotarizationCompleted: Emitted when notarization is completed
Code Reference: contracts/SecuritizationNotarization.sol

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Configuration

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Environment Variables

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SECURITIZATION_NOTARIZATION_CONTRACT
string
SecuritizationNotarization contract address (auto-deployed if empty)
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NOTARIZATION_FEE_ENABLED
boolean
Enable notarization fees. Default: true
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NOTARIZATION_FEE_AMOUNT
decimal
Default notarization fee in USD. Default: 50.00
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NOTARIZATION_FEE_ADMIN_SKIP
boolean
Allow admin users to skip payment requirement. Default: true
Setup Guide: See MetaMask Setup Guide

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User Interface

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Notarization Modal

Location: client/src/components/NotarizationModal.tsx Features:
  • Signer Management: Add/remove required signers
  • Wallet Connection: Connect MetaMask wallet
  • Payment Processing: Handle x402 payment flow
  • Status Display: Show signing progress
  • Completion Handling: Handle notarization completion
Access: Available from document and deal detail views

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CDM Event Integration

All notarizations generate CDM-compliant events: 
{
  "eventType": "SecuritizationNotarization",
  "eventDate": "2026-01-15T10:00:00Z",
  "securitizationNotarization": {
    "poolIdentifier": {
      "issuer": "CreditNexus",
      "assignedIdentifier": [{"identifier": {"value": "pool_123"}}]
    },
    "notarizationHash": "0x...",
    "signers": ["0x...", "0x..."],
    "blockchainTransactionHash": "0x...",
    "notarizationDate": {"date": "2026-01-15"}
  }
}
Code Reference: app/models/cdm_events.py (generate_cdm_securitization_notarization)

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Security Considerations

  1. Signature Verification: All signatures verified using Ethereum signature verification
  2. Nonce Protection: Nonces prevent replay attacks
  3. Signer Validation: Only required signers can sign
  4. Hash Verification: CDM payload hash verified
  5. Blockchain Immutability: Once notarized, records are immutable

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Best Practices

  1. Signer Selection: Choose appropriate signers for each notarization
  2. Message Clarity: Use clear, descriptive message prefixes
  3. Payment Handling: Process payments before notarization
  4. Status Monitoring: Monitor notarization status
  5. CDM Compliance: Ensure all notarizations generate CDM events

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Troubleshooting

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Signature Verification Fails

  • Verify wallet address matches signer address
  • Check message format matches exactly
  • Verify signature format is correct
  • Ensure nonce is current

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Payment Not Processing

  • Verify MetaMask is connected
  • Check network is set to Base
  • Verify USDC balance in wallet
  • Check payment payload format

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Additional Resources

Last Updated: 2026-01-14
Code Reference: app/services/notarization_service.py, app/api/remote_routes.py, contracts/SecuritizationNotarization.sol