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dtg-credentials

Repo: github.com/OpenVTC/dtg-credentials

A Rust library implementing the Decentralized Trust Graph credential types. It provides the data structures and signing/verification logic for the Verifiable Credentials that form the edges of the trust graph.

What It Implements

Version 0.3 of the DTG credential specification from the Trust over IP Foundation’s DTG Working Group Credential Task Force. See DTG Credential Types for the full taxonomy.

Architecture

The library is compact — two source files and an example:

  • lib.rs — Core types: DTGCredential wrapper, DTGCommon (W3C VC structure), DTGCredentialType enum, CredentialSubject variants (Basic, Endorsement, Witness, RCard), signing/verification methods
  • create.rs — Builder methods for each credential type (new_vmc, new_vrc, new_vic, new_vpc, new_vec, new_vwc, new_rcard)

Usage

// Create a Persona Credential
let credential = DTGCredential::new_vpc(issuer_did, subject_did, valid_from, valid_until);
 
// Sign it
credential.sign(&secret, None).await?;
 
// Verify it
credential.verify_proof_with_public_key(&public_key)?;

The library supports both W3C VC 1.1 and 2.0, handling field name differences (issuanceDate/validFrom, expirationDate/validUntil) transparently via serde deserialization.

Dependencies

  • affinidi-data-integrity — W3C Data Integrity proof creation/verification (EdDSA JCS 2022)
  • affinidi-secrets-resolver — key management
  • serde — JSON serialization with camelCase and untagged enum dispatch

Provenance

Originally developed under LF-Decentralized-Trust-labs, recently migrated to the OpenVTC GitHub organization. Being prepared for public release on crates.io.

Recent Development

A dependency-driven point release picks up the upstream data-integrity / TDK 0.7 line. The recent DTG spec changes (bidirectional Edge Credentials in PR #31, ZKP construction split in PR #33) are not yet reflected in this implementation.

v0.1.3 — 2026-06-07 — data-integrity 0.7 / TDK 0.7

  • affinidi-data-integrity 0.6 → 0.7
  • affinidi-tdk 0.6 → 0.7 (dev-dep)
  • sign_and_verify example migrated to the new TDK config builder (TDKConfigBuilder::new() → TDKConfig::builder())
  • MSRV bumped to 1.95.0

v0.1.2 — 2026-04-30

  • Bumped to affinidi-data-integrity 0.6 and migrated to its new API
  • CODEOWNERS for @OpenVTC/openvtc-maintainers

v0.1.1 and earlier — 2026-04 and prior

  • Dependency updates: affinidi-data-integrity 0.4 → 0.5, affinidi-tdk 0.5 → 0.6
  • sign() made async to align with upstream changes
  • Repository URL migration from LF-Decentralized-Trust-labs to OpenVTC
  • Crate publishing enablement

See also: dtg-credentials-overview, decentralized-trust-graph, verifiable-credentials

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