From 99db9a29ad4fd6b2a784b8c8613e8c25a2a2b4af Mon Sep 17 00:00:00 2001
From: Salvatore Ingala <6681844+bigspider@users.noreply.github.com>
Date: Thu, 10 Oct 2019 16:38:34 +0700
Subject: [PATCH] Added signatures to appointment

---
 apps/generate_key.py  |  6 ++++++
 pisa/api.py           |  4 ++--
 pisa/appointment.py   |  4 ++++
 pisa/requirements.txt |  1 +
 pisa/watcher.py       | 11 ++++++++---
 5 files changed, 21 insertions(+), 5 deletions(-)
 create mode 100644 apps/generate_key.py

diff --git a/apps/generate_key.py b/apps/generate_key.py
new file mode 100644
index 0000000..806da97
--- /dev/null
+++ b/apps/generate_key.py
@@ -0,0 +1,6 @@
+import ecdsa
+
+
+if __name__ == '__main__':
+    sk = ecdsa.SigningKey.generate(curve=ecdsa.SECP256k1)
+    print(sk.to_der())
diff --git a/pisa/api.py b/pisa/api.py
index cd05e02..a218af2 100644
--- a/pisa/api.py
+++ b/pisa/api.py
@@ -30,12 +30,12 @@ def add_appointment():
     appointment = inspector.inspect(request_data)
 
     if type(appointment) == Appointment:
-        appointment_added = watcher.add_appointment(appointment)
+        appointment_added, signature = watcher.add_appointment(appointment)
 
         # ToDo: #13-create-server-side-signature-receipt
         if appointment_added:
             rcode = HTTP_OK
-            response = "appointment accepted. locator: {}".format(appointment.locator)
+            response = "appointment accepted. locator: {}. signature: {}".format(appointment.locator, signature)
         else:
             rcode = HTTP_SERVICE_UNAVAILABLE
             response = "appointment rejected"
diff --git a/pisa/appointment.py b/pisa/appointment.py
index 816fde6..39569f9 100644
--- a/pisa/appointment.py
+++ b/pisa/appointment.py
@@ -1,3 +1,5 @@
+import json
+
 from pisa.encrypted_blob import EncryptedBlob
 
 
@@ -22,3 +24,5 @@ class Appointment:
 
         # ToDO: #3-improve-appointment-structure
 
+    def serialize(self):
+        return json.dumps(self.to_json())
diff --git a/pisa/requirements.txt b/pisa/requirements.txt
index 8ec7402..10e961c 100644
--- a/pisa/requirements.txt
+++ b/pisa/requirements.txt
@@ -1,4 +1,5 @@
 zmq
 flask
 cryptography
+ecdsa
 requests
\ No newline at end of file
diff --git a/pisa/watcher.py b/pisa/watcher.py
index 3deda68..e189c9c 100644
--- a/pisa/watcher.py
+++ b/pisa/watcher.py
@@ -1,12 +1,12 @@
 from uuid import uuid4
 from queue import Queue
 from threading import Thread
+import ecdsa
 
 from pisa.logger import Logger
 from pisa.cleaner import Cleaner
-from pisa.conf import EXPIRY_DELTA
+from pisa.conf import EXPIRY_DELTA, MAX_APPOINTMENTS, SIGNING_KEY_DER
 from pisa.responder import Responder
-from pisa.conf import MAX_APPOINTMENTS
 from pisa.block_processor import BlockProcessor
 from pisa.utils.zmq_subscriber import ZMQHandler
 
@@ -22,6 +22,7 @@ class Watcher:
         self.max_appointments = max_appointments
         self.zmq_subscriber = None
         self.responder = Responder()
+        self.sk = ecdsa.SigningKey.from_der(SIGNING_KEY_DER)
 
     def add_appointment(self, appointment):
         # Rationale:
@@ -31,6 +32,8 @@ class Watcher:
         # If the watcher is awake, every new appointment will just be added to the appointment list until
         # max_appointments is reached.
 
+        signature = None
+
         if len(self.appointments) < self.max_appointments:
             # Appointments are identified by the locator: the sha256 of commitment txid (H(tx_id)).
             # Two different nodes may ask for appointments using the same commitment txid, what will result in a
@@ -60,12 +63,14 @@ class Watcher:
 
             logger.info("New appointment accepted.", locator=appointment.locator)
 
+            signature = self.sk.sign(appointment.serialize().encode('utf8'))
+
         else:
             appointment_added = False
 
             logger.info("Maximum appointments reached, appointment rejected.", locator=appointment.locator)
 
-        return appointment_added
+        return (appointment_added, signature)
 
     def do_subscribe(self):
         self.zmq_subscriber = ZMQHandler(parent="Watcher")