public key in a verifiable credential

Hi,
I have a case where I want to include in a VC the public key of the credential subject. I have thought of two approaches:

a) include in the "id" field of "credentialSubject"  a DID method like did:key or did:jwt (this an experimental method by David Chadwick)
b) add in the context of the credential "https://w3id.org/security", or create a credential type that has the property publicKeyJwk, and add inside  "credentialSubject"  something like:

"publicKeyJwk": {
      "crv": "Ed25519", 
      "x": "VCpo2LMLhn6iWku8MKvSLg2ZAoC-nlOyPVQaO3FxVeQ",
      "kty": "OKP", 
 } 

I find the latter approach "cleaner" but I am not sure if it is correct. Any opinion?

Best,
Nikos

--
Nikos Fotiou - http://pages.cs.aueb.gr/~fotiou
Researcher - Mobile Multimedia Laboratory
Athens University of Economics and Business
https://mm.aueb.gr