[SOLVED] Python Flask: Automatically getting or generating SHA-1 fingeriprints

Python Flask: Automatically getting or generating SHA-1 fingeriprints

I've created a simple Flask server that runs on HTTPS, accessible by external devices.

When I connect another device (e.g. an ESP8266) I need to provide the SHA-1 fingerprint.

I have no control over the SHA-1 fingerprint that is generated (and I have no idea how it is generated).

So far I've always had to copy and paste the SHA-1 fingerprint from my browser (firefox): I need to visit the server URL through my browser, click on the lock symbol next to the URL, click on "view certificate" and copy and paste the SHA-1 fingerprint.

The SHA-1 fingerprint changes every time I restart the server, so I have to copy and paste it every time (as just described), which is time-consuming.

I was wondering if there was a way to either:

generating MY OWN SHA-1 fingerprint (so that it is always the same every time I launch the server) OR
automatically getting the SHA-1 fingerprint (maybe through a Flask function?) and printing it on a text file.

I've done some research on the internet but found nothing so far :(

Thank you in advance!

Here's my code:

from flask import Flask, request

app = Flask(__name__)

@app.route("/", methods=["GET"])
def hello():
    return "Hello World!

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=8080, ssl_context='adhoc')

Solution

import ssl, hashlib

cert = ssl.get_server_certificate(('my_server_url', my_server_port))

pem_cert = ssl.PEM_cert_to_DER_cert(cert)
sha1_fingerprint = hashlib.sha1(pem_cert).hexdigest()
print(sha1_fingerprint)

Thank you so much!