"An unexpected error occurred: 'str' object has no attribute 'URI'" Error with client with encryption

[eikelele]

Hi everybody,

this is my first post on GitHub, so I hope I am doing it right posting it here in the Q&A section of discussions.

I am trying to implement an OPC UA-Client with encryption with asyncio/asyncua.

Here is my code:

import asyncio
from asyncua import Client, ua

async def connect_to_opcua():
    server_url = "opc.tcp://hostname:62541/discovery"
    client = Client(server_url)
    print("debug1")
    # Sicherheitseinstellungen konfigurieren
    await client.set_security(
        policy="Basic256Sha256",
        mode = ua.MessageSecurityMode.SignAndEncrypt,
        private_key_password= None,
        certificate="C:/Scripts/my_certificate.der",
        server_certificate= None,
        private_key="C:/Scripts/my_private_key.pem"
    )
    # Benutzeranmeldeinformationen
    client.set_user("test-user")
    client.set_password("password")
    print("debug2")
    try:
        # Verbindung zum Server herstellen
        await client.connect()
        print("Connected to the OPC UA Server.")

        # Führen Sie hier Ihre OPC UA-Operationen aus
        # Beispiel:
        # node = client.get_node("ns=2;s=SomeNodeId")
        # value = await node.get_value()
        # print(f"Node value: {value}")

    finally:
        # Trennen der Verbindung zum Server
        await client.disconnect()
        print("Disconnected from the OPC UA Server.")

async def main():
    try:
        await connect_to_opcua()
    except KeyboardInterrupt:
        print("Program interrupted by the user. Exiting...")
    except Exception as e:
        print(f"An unexpected error occurred: {e}")

if __name__ == "__main__":
    asyncio.run(main())

I always run into the error of:

An unexpected error occurred: 'str' object has no attribute 'URI'.

So i looked up the method Client.set_security and found, that URI is found at the server_certificate.

So I went to the OPC UA-server and there I copied it certificate.der file and tried to use it. But then this happens:

certificate has no SubjectAlternativeName this is need for application verification!
An unexpected error occurred: 'str' object is not callable

I've read about the 2nd error but I can't change the certificate, because I am not the issuer / it is a third party tool (Ignition OPC UA Server).

Anyone here who could help me with this? Thanks in advance and have a great day!