the magic is that you don't need any of that to permissionlessly verify an identity – a custodial SIWE signature is absolute proof of user, a verified address associated with your FID is a reasonably strong signal too – but imparts trust on the app FID that produced the signer. In the Quorum case, you are your own app FID, so your signer is functionally equivalent to your custody key in validating the authenticity of a verified address. So the protocol-driven quick auth has a few simple knobs:
{no channel}