SD-JWT for Dart

The SD-JWT for Dart package provides libraries and tools to enable selective disclosure, enhancing security and privacy in the data-sharing process. It implements the IETF's Selective Disclosure for JWTs (SD-JWT) specification.

The SD-JWT for Dart package enables:

• Issuer to create JWTs with selectively disclosable claims.
• Holder to present only specific claims to verifiers.
• Verifier to validate the authenticity of the presented claims.
• Key binding to prevent unauthorized presentations.

IMPORTANT: This project does not collect or process any personal data. However, when used as part of a broader system or application that handles personally identifiable information (PII), users are responsible for ensuring that any such use complies with applicable privacy laws and data protection obligations.

Table of Contents

• Core Concepts
• Supported Algorithms
• Requirements
• Installation
• Usage
• API Reference
• Support & feedback
  • Reporting technical issues
• Contributing

Core Concepts

SD-JWT introduces several key concepts:

• Selective Disclosure: Claims can be selectively disclosed based on need
• Cryptographic Binding: Claims are cryptographically bound to the JWT
• Key Binding: Ensures only the intended holder can present the SD-JWT
• Disclosures: Individual pieces of information that can be selectively shared

Supported Algorithms

The package supports the following signing algorithms:

• ES256 - ECDSA using P-256 curve and SHA-256
• ES256K - ECDSA using secp256k1 curve and SHA-256
• RS256 - RSASSA-PKCS1-v1_5 using SHA-256
• HS256 - HMAC using SHA-256
• Additional algorithms: RS384, RS512, ES384, ES512, HS384, and HS512

For hash calculation in disclosures:

• SHA-256 (default)
• SHA-384
• SHA-512

You can create your custom signer, hasher, and verifier to extend support for other algorithms. Refer to this example on how to do this.

Requirements

• Dart SDK version ^3.6.0

Installation

Run:

dart pub add selective_disclosure_jwt

or manually, add the package into your pubspec.yaml file:

dependencies:
  selective_disclosure_jwt: ^<version_number>

and then run the command below to install the package:

dart pub get

Usage

After successfully installing the package, import it into your Dart code.

import 'package:selective_disclosure_jwt/selective_disclosure_jwt.dart';

void main() async {
  // ⚠️ CAUTION: The following keys are for quickstart and testing purposes only.
  // These keys are publicly exposed and MUST NOT be used in any production or real project.
  // Always generate and use your own secure keys for real-world use.
  final issuerPrivateKey = SdPrivateKey("""
-----BEGIN PRIVATE KEY-----
MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgRfYYQILHnIkhWOz2
gUl+dfvtkTQDx9OEJaqvKgZaIDuhRANCAATJZsFS61jqyM1ST6riibMlnnA5sTbv
5L1uGdTg7vBADB6xz9AnEMyHnWolqtqXD5n63dw7uDWC1E7jlqzVUOq1
-----END PRIVATE KEY-----
""", SdJwtSignAlgorithm.es256k);

  final issuerPublicKey = SdPublicKey("""
-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEyWbBUutY6sjNUk+q4omzJZ5wObE2
7+S9bhnU4O7wQAwesc/QJxDMh51qJaralw+Z+t3cO7g1gtRO45as1VDqtQ==
-----END PUBLIC KEY-----
""", SdJwtSignAlgorithm.es256k);

  // 1. Create SD-JWT with selective disclosures
  final SdJwtHandlerV1 handler = SdJwtHandlerV1();

  final Map<String, String> claims = {
    'given_name': 'Alice',
    'family_name': 'Smith',
    'email': 'alice@example.com',
  };

  // Specify which claims should be selectively disclosable
  final disclosureFrame = {
    '_sd': ['given_name', 'email'],
  };

  // Sign the claims to produce the SD-JWT
  final SdJwt sdJwt = await handler.sign(
    claims: claims,
    disclosureFrame: disclosureFrame,
    signer: SDKeySigner(issuerPrivateKey),
  );

  print('SD-JWT: ${sdJwt.serialized}');

  // 2. Decode and verify the SD-JWT
  final SdJwt verified = handler.decodeAndVerify(
    sdJwtToken: sdJwt.serialized,
    verifier: SDKeyVerifier(issuerPublicKey),
  );

  print('Verified claims: ${verified.claims}');
  // Output: {family_name: Smith, given_name: Alice, email: alice@example.com}
}

For more examples, go to the example folder.

API Reference

For the available operations, go to the API reference page.

Support & feedback

If you face any issues or have suggestions, please don't hesitate to contact us using this link.

Reporting technical issues

If you have a technical issue with the Affinidi SD-JWT Dart's codebase, you can also create an issue directly in GitHub.

1. Ensure the bug was not already reported by searching on GitHub under Issues.

2. If you're unable to find an open issue addressing the problem, open a new one. Be sure to include a title and clear description, as much relevant information as possible, and a code sample or an executable test case demonstrating the expected behaviour that is not occurring.

Contributing

Want to contribute?

Head over to our CONTRIBUTING guidelines.