Verification Method
class VerificationMethod(val id: String, val type: String, val controller: String, val publicKeyJwk: Jwk? = null)
VerificationMethod expresses verification methods, such as cryptographic public keys, which can be used to authenticate or authorize interactions with the DID subject or associated parties. For example, a cryptographic public key can be used as a verification method with respect to a digital signature; in such usage, it verifies that the signer could use the associated cryptographic private key. Specification Reference: https://www.w3.org/TR/did-core/#verification-methods