ESP32 async SSL (as server) and PC SSL via Wifi (as client)

[nastiliano]

Hello,

After a long time trying to connect my ESP32 device as a client to a MQTT broker with TLS (self-signed certs), finally (thanks lot of people in this forums) I could connect and work: https://github.com/orgs/micropython/discussions/13441

Now I wondering if it's possible too use the same certificates but in annother situation. I wanted to send some information via Wifi from a PC (acting as client) using python "paho" to my ESP32 device that is configured as a server in a async sockets situation.

Yesterday I tried a lot, searching info on the net, and I think I was near to do it, but I think I need some more specific configuration about type of cypher (EC) etc...

Is possible sending encrypted data by Wifi?

Thank you very much

[nastiliano]

Hello,

Sorry, @Carglglz could just give me some link, please?I saw you are so experienced in that.

Thank you very much

[Carglglz]

Now I wondering if it's possible too use the same certificates but in annother situation. I wanted to send some information via Wifi from a PC (acting as client) using python "paho" to my ESP32 device that is configured as a server in a async sockets situation.

You definitely can, isn't paho an MQTT client library?, just connect the PC client to the same MQTT broker and publish to a topic that the ESP32 is subscribed.

Is possible sending encrypted data by Wifi?

Yes that is what MQTT broker with TLS does.

If you don't want to use MQTT but instead a direct connection between PC client and the ESP32 device then just use microdot as a Websocket server and a Websocket client from aiohttp for Python 3 and here for MicroPython micropython-lib/aiohttp

https://microdot.readthedocs.io/en/latest/extensions.html#websocket-support
https://docs.aiohttp.org/en/stable/client_quickstart.html#websockets

[nastiliano]

Hello,

Thanks in advance for fast respond. I apreciate.

1st) Yes of course, I'm already connecting PC and ESP32 via MQTT (TLS) is perfect. Thank you very much.

2nd) Ok, thanks, but I wanted to connect not with a websocket server, I wanted to create a connection directly by Wifi with TLS encrypted data. The ESP32 device as a async socket server and PC as a client. Now I'm doing this by my own encryption simply using RSA encryption, then Python sockets sending to my ESP32 as a async server, but I wondered if I could do something more sofisticaded wraping sockets in TLS protocol.

Thanks, best regards.

[Carglglz]

but I wondered if I could do something more sofisticaded wraping sockets in TLS protocol.

Yes of course then just use SSLContext see ssl and e.g. asyncio_tls_server_client.py 👍🏼

[nastiliano]

Hello again :)

After dozens of tries (changing little thigs), I've got always the same error in my ESP32 device (as a server). It seems that async coro "handle_connection" tries to receive but there's a problem with TLS certificates and the memory of device is overflows (at least this is that I believe, heheh...):

Traceback (most recent call last):
    File "asyncio/stream.py", line 1, in _serve
OSError: [Errno 12] ENOMEM

My PC code (client):

# Create an SSL context
context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
context.verify_mode = ssl.CERT_REQUIRED
context.check_hostname = False

# Load CA certificate with which the client will validate the server certificate
context.load_verify_locations(os.path.join(folder_certs  , "ec_cert.crt"))

# Create a client socket
self.socket = socket.socket (socket.AF_INET, socket.SOCK_STREAM)

# Make the client socket suitable for secure communication
self.socket  = context.wrap_socket(self.socket)

# Data
self.data = "hello world"

with self.socket:
    # Timeout
    self.sosket.settimeout(5)

        try:
        self.socket((self.IP , 8000))
        self.socket(self.data)

My ESP32 code (server):

async def main():

   # wifi config
   # ....

    async def handle_connection(reader, writer):
        data = await reader.read(100)
        print("echo:", data)

    cert = cafile = "/certs/ec_cert.der"
    key = "/certs/ec_key.der"

    os.stat(cafile)
    os.stat(key)

    server_ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
    server_ctx.load_cert_chain(cert, key)

    server = await asyncio.start_server(handle_connection, "192.168.1.200", 8000 , ssl = server_ctx)
    await asyncio.gather(server , otherts())

asyncio.run(main())

Any clue please? :)

Thank you very much.

[nastiliano]

Hello,

Just the last little help please @Carglglz?

Thank you very much.