bugLogIf(ctx, err)
			writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, err), r.URL)
			return
		}

		// Write a version for making *incompatible* changes.
		// The AdminClient will reject any version it does not know.
		if publicKey == nil {
			w.Write([]byte{1})
			w.Write(key[:])
		}

		stream, err := sio.AES_256_GCM.Stream(key[:])
		if err != nil {
			bugLogIf(ctx, err)
			return