DIDComm V2 Implementation Summary

Overview

This document summarizes the DIDComm V2 implementation for TrustWeave.

Implementation Status

✅ Complete - Core implementation is complete with the following components:

Core Components

1. Message Models (models/)
   • DidCommMessage: JWM-format message structure
   • DidCommEnvelope: Encrypted message envelope
   • DidCommAttachment: Message attachments for credentials/presentations
2. Cryptography (crypto/)
   • DidCommCrypto: ECDH-1PU key agreement and AES-256-GCM encryption
   • ⚠️ Note: Uses placeholder implementations for ECDH-1PU. For production, integrate a full DIDComm library.
3. Message Packing (packing/)
   • DidCommPacker: Packs/unpacks messages (encryption/decryption)
4. Service Interface (DidCommService.kt)
   • DidCommService: Interface for messaging operations
   • InMemoryDidCommService: In-memory implementation
5. Protocol Helpers (protocol/)
   • CredentialProtocol: Issue Credential protocol messages
   • ProofProtocol: Present Proof protocol messages
   • BasicMessageProtocol: Basic message protocol
6. Utilities (utils/)
   • DidCommUtils: Helper functions for DID document operations
7. Exceptions (exceptions/)
   • Custom exception types for DIDComm operations
8. Factory (DidCommFactory.kt)
   • Factory methods for creating services
9. Examples (examples/)
   • Usage examples for common scenarios

File Structure

credentials/plugins/didcomm/
├── build.gradle.kts
├── README.md
├── IMPLEMENTATION.md
└── src/
    ├── main/
    │   └── kotlin/
    │       └── org.trustweave/didcomm/
    │           ├── crypto/
    │           │   └── DidCommCrypto.kt
    │           ├── models/
    │           │   ├── DidCommMessage.kt
    │           │   └── DidCommEnvelope.kt
    │           ├── packing/
    │           │   └── DidCommPacker.kt
    │           ├── protocol/
    │           │   ├── BasicMessageProtocol.kt
    │           │   ├── CredentialProtocol.kt
    │           │   └── ProofProtocol.kt
    │           ├── utils/
    │           │   └── DidCommUtils.kt
    │           ├── exceptions/
    │           │   └── DidCommExceptions.kt
    │           ├── examples/
    │           │   └── DidCommExamples.kt
    │           ├── DidCommFactory.kt
    │           └── DidCommService.kt
    └── test/
        └── kotlin/
            └── org.trustweave/didcomm/
                └── DidCommServiceTest.kt

Supported Protocols

Issue Credential Protocol

• ✅ offer-credential: Credential offer message
• ✅ request-credential: Credential request message
• ✅ issue-credential: Credential issue message
• ✅ ack: Acknowledgment message

Present Proof Protocol

• ✅ request-presentation: Proof request message
• ✅ presentation: Proof presentation message
• ✅ ack: Acknowledgment message

Basic Message Protocol

• ✅ message: Simple text messages

Features

• ✅ JWM (JSON Web Message) format support
• ✅ Message encryption structure (ECDH-1PU placeholder)
• ✅ AES-256-GCM content encryption
• ✅ Message packing/unpacking
• ✅ Protocol message builders
• ✅ Message threading support
• ✅ In-memory message storage
• ✅ DID document utilities
• ✅ Comprehensive exception handling
• ✅ Usage examples and tests

Dependencies

• credentials:credential-core - For credential models
• did:did-core - For DID document models
• kms:kms-core - For key management
• common - For common utilities
• bouncycastle - For cryptographic operations
• nimbus-jose-jwt - For JWT/JWS operations
• okhttp - For HTTP operations (future use)

Usage Example

import org.trustweave.credential.didcomm.*
import org.trustweave.credential.didcomm.protocol.*
import org.trustweave.testkit.InMemoryKeyManagementService

val kms = InMemoryKeyManagementService()
val resolveDid: suspend (String) -> DidDocument? = { /* resolve DID */ }

val didcomm = DidCommFactory.createInMemoryService(kms, resolveDid)

// Send a basic message
val message = BasicMessageProtocol.createBasicMessage(
    fromDid = "did:key:alice",
    toDid = "did:key:bob",
    content = "Hello!"
)

didcomm.sendMessage(
    message = message,
    fromDid = "did:key:alice",
    fromKeyId = "did:key:alice#key-1",
    toDid = "did:key:bob",
    toKeyId = "did:key:bob#key-1"
)

Production Readiness

✅ Ready

• Message structure and models
• Protocol message builders
• Message packing/unpacking structure
• Service interface and in-memory implementation
• Utility functions
• Exception handling
• Tests and examples

⚠️ Needs Production Implementation

1. Cryptography: Replace placeholder ECDH-1PU with full implementation
   • Consider using didcomm-java library
   • Or implement full ECDH-1PU key agreement
2. Message Delivery: Implement actual message transport
   • HTTP POST to DIDComm service endpoints
   • WebSocket support
   • Message queue integration
3. Persistent Storage: Replace in-memory storage
   • Database-backed message storage
   • Message indexing and search
   • Thread management
4. Key Management: Enhance key handling
   • Private key access for decryption
   • Key rotation support
   • Key derivation from KMS
5. Error Handling: Expand error scenarios
   • Network failures
   • Invalid message formats
   • Missing keys
   • DID resolution failures

Next Steps

1. Integrate Full DIDComm Library
   • Evaluate didcomm-java or similar libraries
   • Replace placeholder crypto implementations
   • Ensure full DIDComm V2 compliance
2. Add Message Transport
   • HTTP client for DIDComm service endpoints
   • WebSocket support for real-time messaging
   • Message queue integration
3. Enhance Storage
   • Database-backed message storage
   • Message search and filtering
   • Thread management
4. Add Integration Tests
   • End-to-end credential exchange tests
   • Proof presentation tests
   • Error scenario tests
5. Documentation
   • API reference
   • Integration guide
   • Protocol-specific guides

References

• DIDComm V2 Specification
• JWM Specification
• Issue Credential Protocol
• Present Proof Protocol