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Overview

The W3C Verifiable Credential (VC) standard provides a framework for creating machine-verifiable, tamper-resistant ITMO (Internationally Transferred Mitigation Outcome) certificates for carbon trading and cross-border climate initiatives. ITMOs are standardized units representing greenhouse gas emission reductions that can be transferred between countries under Article 6.2 of the Paris Agreement. This guide explains how to implement ITMO certificates and use the accompanying JSON-LD context.

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Key Benefits

  • Cryptographic Trust - Signatures ensure authenticity and detect tampering
  • Global Standards - W3C format enables cross-platform compatibility
  • Extensible Design - JSON-LD approach allows adding properties without breaking changes
  • Privacy Controls - Selective disclosure of sensitive transaction details
  • Provenance Tracking - Built-in support for tracking credential history

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Schema Structure

Each ITMO credential contains:

{
  "@context": ["Base contexts and ITMO context"],
  "id": "Unique credential identifier",
  "type": ["VerifiableCredential", "ITMOCredential"],
  "issuer": "DID of issuing entity",
  "issuanceDate": "Issuance timestamp",
  "expirationDate": "Expiration timestamp",
  "credentialSubject": {
    // ITMO-specific data sections
  },
  "credentialSchema": "Schema reference",
  "credentialStatus": "Status information",
  "evidence": "Supporting documentation",
  "proof": "Cryptographic proof"
}

The credentialSubject contains four main ITMO-specific sections:

  • authorizationInfo - Authorization details and participating parties
  • ndcQuantification - NDC sectors, sources, and GHG information
  • correspondingAdjustments - Adjustment calculations and emissions data
  • environmentalIntegrity - Environmental integrity metrics and compliance

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JSON-LD Context

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Setup

Add the ITMO and required contexts to your credential:

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://w3id.org/security/suites/ed25519-2018/v1",
    {
      "itmo": "https://w3id.org/article6/itmo-context.jsonld",
      "prov": "http://www.w3.org/ns/prov#"
    }
  ]
}

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Core Properties

The ITMO context defines these key sections:

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Authorization Information

  • authorizationReference - Reference ID for the authorization
  • cooperativeApproachDuration - Time period of the approach
  • expectedMitigationOutcomes - Expected outcomes by year
  • participatingParties - List of participating countries
  • authorizedEntities - List of authorized entity DIDs

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NDC Quantification

  • ndcSectors - Covered sectors (e.g., “Residential”)
  • ndcSources - Emission sources
  • ndcGHGs - Covered greenhouse gases
  • ndcTimePeriods - Relevant time periods
  • ndcReferenceLevel - Reference emission levels
  • ndcTargetLevel - Target emission levels

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Corresponding Adjustments

  • singleYearNDC - Single year NDC flag
  • multiYearNDC - Multi year NDC flag
  • emissionsTrajectory - Emissions trajectory data
  • annualCorrespondingAdjustments - Annual adjustment values
  • averageAnnualITMOs - Average annual ITMO amount
  • cumulativeAdjustments - Cumulative adjustment total

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Environmental Integrity

  • environmentalIntegrityMetrics - Used metrics (e.g., “CO2e”)
  • ipccMethodologiesReference - IPCC methodology reference
  • partyStatusUnderParis - Paris Agreement status
  • trackingArrangements - Links to tracking systems
  • mostRecentNationalInventory - Latest inventory reference

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Implementation Example

Here’s a minimal example of creating an ITMO credential:

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://w3id.org/security/suites/ed25519-2018/v1",
    {
      "itmo": "https://w3id.org/article6/itmo-context.jsonld",
      "prov": "http://www.w3.org/ns/prov#"
    }
  ],
  "type": ["VerifiableCredential", "ITMOCredential"],
  "issuer": "did:example:issuer",
  "issuanceDate": "2024-03-15T00:00:00Z",
  "credentialSubject": {
    "id": "did:example:subject",
    "itmo:authorizationInfo": {
      "itmo:authorizationReference": "AUTH-2024-001",
      "itmo:participatingParties": ["Country A"],
      "itmo:expectedMitigationOutcomes": {
        "2024": 5000
      }
    }
  }
}

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Validation Requirements

Technical checks:

  • JSON-LD context validation
  • Schema conformance
  • Cryptographic proof verification
  • Credential status verification

Business rules:

  • Required ITMO fields present
  • Valid participating parties
  • Environmental integrity compliance
  • NDC alignment verification

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Security and Privacy

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Security Best Practices

  • Use Ed25519 signatures for proofs
  • Implement proper key management
  • Regular credential status updates
  • Monitor for revoked credentials

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Privacy Guidelines

  • Enable selective disclosure of sensitive data
  • Implement minimal disclosure principle
  • Define clear data retention policies
  • Comply with relevant privacy regulations

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Resources