Update app.py

app.py

@@ -32,9 +32,18 @@ def get_san_list(cert):
         return []
 
 def extract_certificate_details(cert):
+    """
+    Extract key details from the certificate, including issuer, subject, fingerprints, and validity.
+
+    Args:
+        cert (x509.Certificate): The certificate object.
+
+    Returns:
+        dict: Dictionary containing certificate details.
+    """
     now = datetime.now(timezone.utc)
-    expiry_date = cert.not_valid_after
-    not_before = cert.not_valid_before
+    expiry_date = cert.not_valid_after.replace(tzinfo=timezone.utc)
+    not_before = cert.not_valid_before.replace(tzinfo=timezone.utc)
     days_remaining = (expiry_date - now).days
     fingerprints = get_fingerprints(cert)
     san_list = get_san_list(cert)
@@ -49,6 +58,7 @@ def extract_certificate_details(cert):
         "san_list": san_list,
     }
 
+
 def establish_tls_connection(hostname, port, timeout):
     context = ssl.create_default_context()
     context.check_hostname = False