https://github.com/nostr-protocol/nips/pull/831#issuecomment-1822940276

> by "peer-pubkey" I mostly just mean this is not the client pubkey and not the signer pubkey, but a random other persons pubkey.

署名者の pubkey もクライアントの pubkey も、`kind: 24133` のイベントでわかるので、ランダムな pubkey？