What's Next for Verifiable Credentials

Wesley Smith

Mandy Venables

TPAC 2024
Anaheim CA, USA
hybrid meeting
23–27 SEPTEMBER 2024

What should go into a new charter? (1/3)

Features

RenderMethod
ConfidenceMethod
Unlinkable ECDSA Cryptosuite

What should go into a new charter? (2/3)

Protocols

Verifiable Credentials API
Verifiable Credentials over Bluetooth
Verifiable Credentials over NFC

What should go into a new charter? (3/3)

Applications

Verifiable Credential Barcodes
Vocabulary Work
1. Verifiable Driver's Licenses
2. Citizenship Vocabulary (Employment Authorization Documents etc.)
3. Verifiable Vehicle Titles

Features

renderMethod (1/2)

A secure way for issuers to convey how they want their credentials displayed

Represent Verifiable Credential through visual, auditory, or haptic medium
Experimenting with SVG, PDF, and other text-based template formats

renderMethod (2/2)

A secure way for issuers to convey how they want their credentials displayed

Production deployments in Singapore for Open Attestation Renderer
Examples deployed in Playground, standardization ETA 6-12 months
Multiple implementations (none interoperable yet)

renderMethod example

"renderMethod": [{
  "id":
    "https://example.edu/credentials/BachelorDegree.svg",
  "type": "SvgRenderingTemplate",
  "name": "Portrait Mode",
  "css3MediaQuery": "@media (orientation: portrait)",
  "digestMultibase":
    "zQmAPdhyxzznFCwYxAp2dRerWC85Wg6wFl9G270iEu5h6JqW"
}]

confidenceMethod

Increase credential accuracy and trustworthiness

Gives confidence the entity presenting the credential is the one that picked it up
Can be bound to a hardware key
Can use other unlinkable and non-correlatable methods

confidenceMethod example

"confidenceMethod": [{
  "type": "VerificationKeyConfirmation",
  "publicKeyJwk": {
    "kty": "EC",
    "crv": "P-256",
    "x": "f83OJ3D2xFzv3SKnli_J9i7Fy1oD2m5wdJGJVAOzvZ0",
    "y": "x_FEzRu9-4sM8c4JLAuO4ZF2_CfAhFb6tkcU8QpF9Ck"
  }}]

Unlinkable ECDSA Cryptosuite

Adding unlinkability to traditional signature mechanisms

Traditional ECDSA signatures strongly linkable
Working with expert cryptographers to add unlinkability
Unlinkability can be achieved with other signature mechanisms, but you lose good properties of ECDSA:
1. FIPS compliance
2. Wide hardware/software support
Early phases of work, specification draft within a year

Protocols

Verifiable Credentials API (1/3)

An API for performing Verifiable Credential lifecycle management

Complete credential lifecycle management framework, supports:
1. Issuance
2. Verification
3. Presentation
4. Status Modification

Verifiable Credentials API (2/3)

An API for performing Verifiable Credential lifecycle management

Agnostic to delivery mechanism:
1. DIDComm
2. OID4
3. Workflows/Exchanges
4. Conexxus API

Verifiable Credentials API (3/3)

An API for performing Verifiable Credential lifecycle management

11 implementations (varying levels of interoperability)
Used extensively in VCWG for test suites and canivc.com
Production deployments (TruAge, CA DMV/OpenCred)

Verifiable Credentials over Wireless NFC (1/2)

Protocols for in-person VC Presentation

Mechanisms:
- NFC
- Bluetooth
Specification draft

Verifiable Credentials over Wireless NFC (2/2)

Protocols for in-person VC Presentation

Applications:

First responder on-site presentation
Border crossing
Retail or venue interactions

Applications

Verifiable Credential Barcodes (1/2)

Cryptographic security for physical credentials

Barcodes encode VCs into easily consumable format
Uses new Data Integrity cryptosuite to digitally sign both VC, optically readable data on card
- MRZ on Employment Authorization Doc.
- PDF417 on Driver's License

Verifiable Credential Barcodes (2/2)

Cryptographic security for physical credentials

Multiple implementations in progress
Test vectors available in VCB specification
Deployments in progress:
- California Department of Motor Vehicles
- Department of Homeland Security

Citizenship Vocabulary

A Linked Data vocabulary for expressing attributes related to citizenship

Use case: VCs for representing citizenship as recognized by an issuing organization (e.g. a federal government)
Deployment in progress with USCIS

Verifiable Driver's License Vocabulary

A Linked Data vocabulary for expressing attributes related to digital driver's licenses

Use case: VCs for digital driver's licenses
Deployed in production with CA DMV

Verifiable Vehicle Titles Vocabulary

A Linked Data vocabulary for expressing attributes related to vehicle titling and ownership

Use case: VCs for provable ownership of a vehicle as recognized by an issuing organization (e.g. a state government)
Deployment in progress with CA DMV

Summary

Three main categories of proposed work:

Features
Protocols
Applications

Standardization timelines for proposed items vary based on maturity

Lots of exciting work to be done :)