diff --git a/app.py b/app.py
index 7a74f2b..8614794 100644
--- a/app.py
+++ b/app.py
@@ -4,6 +4,7 @@ A simple Flask application for interacting with WHSPAH shockers.
 
 import argparse
 import logging
+import random
 import json
 import os
 
@@ -58,19 +59,22 @@ def transmit():
         txID = int(data['transmitterID'])
         channel = int(data['channel'])
         action = ACTION_MAP[data['action']]
+        pin = int(data['shockerPin'])
         intensity = int(data.get('intensity', 0))
         lucal = bool(data.get('lucalEncoded', False))
-        pin = int(data['shockerPin'])
     # If any of those failed, return an error.
     except (ValueError, KeyError):
         return {'success': False, 'message': 'Request must contain the following keys:\n'+
                                              'txID: int,\n'+
                                              'channel: int,\n'+
-                                             'pin: int,\n'+
                                              'action: "shock", "vibrate" or "beep",\n'+
+                                             'pin: int,\n'+
                                              'intensity (optional): int\n'+
                                              'lucalEncoded (optional): bool'}, 400
 
+    if pin != app.config['pin']:
+        return {'success': False, 'message': 'Unauthorised'}, 401
+
     # Send the data to WHSPAH
     tx: whspah.Transmitter = app.config['transmitter']
     tx.transmit(txID, channel, action, intensity, lucal)
@@ -85,6 +89,9 @@ if __name__ == '__main__':
     parser.add_argument('-d', '--debug', action='store_true')
     parser.add_argument('--ip', type=str, default='0.0.0.0')
     parser.add_argument('--port', type=int, default=8000)
+    parser.add_argument('--pin', type=int, default=random.randint(1000, 9999),
+                        help='The authorisation pin, defaults to a random number'+
+                             'between 1000 and 9999')
     args = parser.parse_args()
 
     # Sets the logging version based on --debug
@@ -96,6 +103,10 @@ if __name__ == '__main__':
     # Connect to a WHSPAH device
     app.config['transmitter'] = whspah.Transmitter()
 
+    # Configure pin
+    app.config['pin'] = args.pin
+    print(f'Running with pin {args.pin}.')
+
     if args.debug:
         # If in debug mode, run Flask's built in server
         app.run(host=args.ip, port=args.port, debug=True)