Handoff serialization to jupyter-client

Author: krassowski

ipykernel/heartbeat.py

@@ -36,11 +36,11 @@ def __init__(self, context, addr=None, curve_publickey=None, curve_secretkey=Non
         addr : tuple, optional
             (transport, ip, port)
         curve_publickey : bytes, optional
-            Z85-encoded CurveZMQ public key.  When provided together with
+            CurveZMQ public key (Z85). When provided together with
             *curve_secretkey*, the heartbeat socket will operate as a
             CurveZMQ server so that only authenticated clients can connect.
         curve_secretkey : bytes, optional
-            Z85-encoded CurveZMQ secret key (paired with *curve_publickey*).
+            CurveZMQ secret key (Z85, paired with *curve_publickey*).
         """
         if addr is None:
             addr = ("tcp", localhost(), 0)

ipykernel/kernelapp.py

@@ -299,11 +299,9 @@ def write_connection_file(self, **kwargs: Any) -> None:
             control_port=self.control_port,
         )
         if self.enable_curve and self._curve_publickey is not None:
-            # Store Z85-encoded keys as ASCII strings alongside the HMAC key.
-            # Clients that understand CurveZMQ will use these to configure
-            # their sockets; legacy clients ignore the unknown fields.
-            connection_info["curve_publickey"] = self._curve_publickey.decode("ascii")
-            connection_info["curve_secretkey"] = self._curve_secretkey.decode("ascii")  # type: ignore[union-attr]
+            # write_connection_file() in jupyter-client handles JSON-safe key serialization
+            connection_info["curve_publickey"] = self._curve_publickey
+            connection_info["curve_secretkey"] = self._curve_secretkey
         if Path(cf).exists():
             # If the file exists, merge our info into it. For example, if the
             # original file had port number 0, we update with the actual port