From ca64b5927790eb13979a018835fadb13c5879c8b Mon Sep 17 00:00:00 2001
From: Salvatore Ingala <6681844+bigspider@users.noreply.github.com>
Date: Fri, 18 Oct 2019 13:18:39 +0800
Subject: [PATCH] Added signature verification to pisa_cli

---
 apps/cli/__init__.py |  2 ++
 apps/cli/pisa-cli.py | 39 +++++++++++++++++++++++++++++++++++++--
 pisa/watcher.py      |  4 ++--
 3 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/apps/cli/__init__.py b/apps/cli/__init__.py
index 20bb9fb..0be0f2a 100644
--- a/apps/cli/__init__.py
+++ b/apps/cli/__init__.py
@@ -11,6 +11,8 @@ CLIENT_LOG_FILE = 'pisa.log'
 SUPPORTED_HASH_FUNCTIONS = ["SHA256"]
 SUPPORTED_CIPHERS = ["AES-GCM-128"]
 
+PUBLIC_KEY_FILE = "signing_key_pub.pem"
+
 # Configure logging
 logging.basicConfig(format='%(message)s', level=logging.INFO, handlers=[
     logging.FileHandler(CLIENT_LOG_FILE),
diff --git a/apps/cli/pisa-cli.py b/apps/cli/pisa-cli.py
index 8b181a1..beb7298 100644
--- a/apps/cli/pisa-cli.py
+++ b/apps/cli/pisa-cli.py
@@ -9,14 +9,25 @@ from binascii import unhexlify
 from getopt import getopt, GetoptError
 from requests import ConnectTimeout, ConnectionError
 
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.serialization import load_pem_public_key
+from cryptography.hazmat.primitives.asymmetric import ec
+from cryptography.exceptions import InvalidSignature
+
 from pisa.logger import Logger
 from apps.cli.blob import Blob
 from apps.cli.help import help_add_appointment, help_get_appointment
-from apps.cli import DEFAULT_PISA_API_SERVER, DEFAULT_PISA_API_PORT
+from apps.cli import DEFAULT_PISA_API_SERVER, DEFAULT_PISA_API_PORT, PUBLIC_KEY_FILE
 
+HTTP_OK = 200
 
 logger = Logger("Client")
 
+with open(PUBLIC_KEY_FILE, "r") as key_file:
+    pubkey_pem = key_file.read().encode("utf-8")
+    pisa_public_key = load_pem_public_key(pubkey_pem, backend=default_backend())
+
 
 # FIXME: TESTING ENDPOINT, WON'T BE THERE IN PRODUCTION
 def generate_dummy_appointment():
@@ -75,13 +86,37 @@ def add_appointment(args):
                 try:
                     r = requests.post(url=add_appointment_endpoint, json=json.dumps(appointment), timeout=5)
 
-                    logger.info("{} (code: {}).".format(r.text, r.status_code))
+                    logger.info("{} (code: {}).".format(r.json(), r.status_code))
+
+                    response_json = r.json()
+
+                    if r.status_code == HTTP_OK:
+                        if 'signature' not in response_json:
+                            logger.error("The response does not contain the signature of the appointment.")
+                        else:
+                            # verify that the returned signature is valid
+                            signature = response_json['signature']
+                            pisa_public_key.verify(signature.encode("utf-8"), data, ec.ECDSA(hashes.SHA256()))
+                    else:
+                        if 'error' not in response_json:
+                            logger.error("The server returned status code {}, but no error description."
+                                         .format(r.status_code))
+                        else:
+                            error = r.json()['error']
+                            logger.error("The server returned status code {}, and the following error: {}."
+                                         .format(r.status_code))
+
+                except json.JSONDecodeError:
+                    logger.error("The response was not valid JSON.")
 
                 except ConnectTimeout:
                     logger.error("Can't connect to pisa API. Connection timeout.")
 
                 except ConnectionError:
                     logger.error("Can't connect to pisa API. Server cannot be reached.")
+
+                except InvalidSignature:
+                    logger.error("The returned appointment's signature is invalid.")
             else:
                 logger.error("The provided locator is not valid.")
     else:
diff --git a/pisa/watcher.py b/pisa/watcher.py
index eee3159..91a9cf0 100644
--- a/pisa/watcher.py
+++ b/pisa/watcher.py
@@ -31,8 +31,8 @@ class Watcher:
             raise ValueError("No signing key provided. Please fix your pisa.conf")
         else:
             with open(SIGNING_KEY_FILE, "r") as key_file:
-                pubkey_pem = key_file.read().encode("utf-8")
-                self.signing_key = load_pem_private_key(pubkey_pem, password=None, backend=default_backend())
+                privkey_pem = key_file.read().encode("utf-8")
+                self.signing_key = load_pem_private_key(privkey_pem, password=None, backend=default_backend())
 
     def add_appointment(self, appointment):
         # Rationale: