PasswordProtectedKeySignature

Signature produced by a key pair whose private half the client decrypted with their password. On
the wire it is identical to a raw key-pair signature - the password never leaves the browser - but
the provider is told which mechanism it was, so the two are separate shapes here as well.

{
    "kind": "passwordProtectedKey",
    "credentialId": "string",
    "clientData": "string",
    "signature": "string",
    "algorithm": "string"
}