Identifier Methods

Verifiable Credentials allow flexible methods for identifying the issuer, the subject, and holder. The identifier data type is a URI, which can be a web page, Solid profile, a decentralized identifier (DID), etc.

The default implementations use did:abaxx, did:key, did:ion and did:web for convenience and simplicity, but you should use the identifier method that is appropriate for your requirements.

On the subject/holder side, we chose did:key because it requires no fees or blockchain dependencies. It's a purely generative method, enabling resolution offline, without any registry lookups. This enables identity wallet applications to mimic the behavior of existing crypto wallets.

At the same time, did:key does not support key rotation, which is sometimes a desired DID method characteristic, especially for issuers. A simple option for issuers with long-standing web domains and established processes for pushing updates is to use did:web.

DID Methods

There are a large number of DID methods, some of which are based on blockchains, some based on web pages, and some purely generative. Some may support a complete range of DID operations like update, and others (like did:key) may not.

While implementors may choose any method they like, some common factors include:

• technical feasibility

• open source implementations (demonstrating interoperability)

• no/low fee

• issuers, verifiers, and holder wallets to resolve DIDs without relying on a specific tenant or chain

In general, DID method options will be influenced by a broader set of criteria relevant to all roles in the network, a comprehensive consideration of which is available in the DID Method Rubric.