chapter seven

7 Verifiable credentials

 

by David W. Chadwick and Daniel C. Burnett

Verifiable credentials (abbreviated as “VCs”), are the very heart of SSI architecture. In this chapter, you will learn how VCs evolved, what they look like as data structures, what different formats and digital signature options are supported, and how VCs have been standardized at World Wide Web Consortium (W3C). Your guides will be two of the primary authors of the W3C Verifiable Credentials Data Model 1.0 standard: David Chadwick, Professor of Information Systems Security at the University of Kent, and Dan Burnett, Blockchain Standards Architecture in the PegaSys group at ConsenSys. Daniel also served as co-chair of the W3C Verifiable Claims Working Group that created the VC standard.

We all use physical verifiable credentials (VCs) many times each day (even though you may not realize it). Examples include plastic credit cards, driving licenses, passports, membership cards, bus passes, and more. We can’t live without them because they provide us with many benefits. In fact, we wouldn’t possess them if they didn’t provide us with some benefits. There would be no point.

7.1       Example Usages of VCs

7.1.1   Opening a bank account

7.1.2   Receiving a free local access pass

7.1.3   Using an electronic prescription

7.2       The VC ecosystem

7.3       The VC trust model

7.3.1   Federated identity management vs. VCs

7.3.2   Specific trust relationships in the VC trust model

7.3.3   Bottom-up trust

7.4       W3C and the VC standardization process

7.5       Syntactic Representations

7.5.1   JSON

7.5.2   Beyond JSON - adding standardized properties

7.5.3   JSON-LD

7.5.4   JWT

7.6       Basic VC Properties

7.7       Verifiable presentations

7.8       More Advanced VC Properties

7.8.1   Refresh Service

7.8.2   Disputes

7.8.3   Terms of Use

7.8.4   Evidence