Feature/SK-1330 | Use host cert store instead of downloading cert (#793)

* Remove download of cert

* Removed unused imports

fedn/network/clients/grpc_handler.py

@@ -1,15 +1,12 @@
 import json
 import os
-import socket
 import time
 from datetime import datetime
 from io import BytesIO
 from typing import Any, Callable
 
 import grpc
-from cryptography.hazmat.primitives.serialization import Encoding
 from google.protobuf.json_format import MessageToJson
-from OpenSSL import SSL
 
 import fedn.network.grpc.fedn_pb2 as fedn
 import fedn.network.grpc.fedn_pb2_grpc as rpc
@@ -44,21 +41,6 @@ def __call__(self, context, callback):
         callback((("authorization", f"{FEDN_AUTH_SCHEME} {self._key}"),), None)
 
 
-def _get_ssl_certificate(domain, port=443):
-    context = SSL.Context(SSL.TLSv1_2_METHOD)
-    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-    sock.connect((domain, port))
-    ssl_sock = SSL.Connection(context, sock)
-    ssl_sock.set_tlsext_host_name(domain.encode())
-    ssl_sock.set_connect_state()
-    ssl_sock.do_handshake()
-    cert = ssl_sock.get_peer_certificate()
-    ssl_sock.close()
-    sock.close()
-    cert = cert.to_cryptography().public_bytes(Encoding.PEM).decode()
-    return cert
-
-
 class GrpcHandler:
     def __init__(self, host: str, port: int, name: str, token: str, combiner_name: str):
         self.metadata = [
@@ -95,9 +77,7 @@ def _init_secure_channel(self, host: str, port: int, token: str):
             self.channel = grpc.secure_channel("{}:{}".format(host, str(port)), credentials)
             return
 
-        logger.info(f"Fetching SSL certificate for {host}")
-        cert = _get_ssl_certificate(host, port)
-        credentials = grpc.ssl_channel_credentials(cert.encode("utf-8"))
+        credentials = grpc.ssl_channel_credentials()
         auth_creds = grpc.metadata_call_credentials(GrpcAuth(token))
         self.channel = grpc.secure_channel(
             "{}:{}".format(host, str(port)),