Add encryption module

server/app/models.py

@@ -0,0 +1,22 @@
+from banjo.models import (
+    Model, 
+    StringField, 
+    ForeignKey,
+    BooleanField,
+)
+
+class User(Model):
+    name = StringField(unique=True)
+    public_key = StringField(unique=True)
+
+    def to_dict(self):
+        return {
+            'name': self.name,
+            'public_key': self.public_key,
+        }
+
+class Message(Model):
+    sender = ForeignKey(User, related_name="messages_sent")
+    recipient = ForeignKey(User, related_name="messages_received")
+    ciphertext = StringField()
+    read = BooleanField()

server/app/views.py

@@ -0,0 +1,62 @@
+from banjo.urls import route_get, route_post
+from app.models import User, Message
+from banjo.http import NotFound, NotAllowed
+from datetime import datetime
+import rsa
+
+@route_post("users/new", args={'name': str, 'public_key': str})
+def create_user(params):
+    "Creates a new user"
+    try:
+        new_user = User.from_dict(params)
+        new_user.save()
+        return new_user.to_dict()
+    except:
+        raise NotAllowed("Username and public key must be unique.")
+
+@route_get("users", args={'name': str})
+def get_user(params):
+    "Get a user's public key"
+    try:
+        user = User.objects.get(name=params['name'])
+        return user.to_dict()
+    except User.DoesNotExist:
+        raise NotFound(f"There is no user named {params['name']}")
+
+@route_get("messages", args={'name': str})
+def get_messages(params):
+    "Return all the messages for a user"
+    try:
+        user = User.objects.get(name=params['name'])
+    except User.DoesNotExist:
+        raise NotFound(f"There is no user named {params['name']}")
+    messages = Message.objects.filter(user=user)
+    return {'messages': [m.to_dict() for m in messages]}
+
+@route_get("messages/send", args={'sender': str, 'recipient': str, 'ciphertext': str,
+        'time_sent': str, 'auth': str})
+def send_message(params):
+    """Securely sends an encrypted message from `sender` to `recipient`
+    Sender and recipient should be recognized usernames. 
+    Time sent should be the time the message was sent in isoformat.
+    Auth should be the time sent, encrypted with the sender's private key.
+    The ciphertext should be encrypted with the recipient's public key.
+    """
+    try:
+        sender = User.objects.get(name=params['sender'])
+        recipient = User.objects.get(name=['recipient'])
+    except User.DoesNotExist:
+        raise NotFound(f"There is no user named {params['name']}")
+    try: 
+        time_sent = datetime.fromisoformat(params['time_sent'])
+    except ValueError:
+        raise NotAllowed(f"Time sent ({params['time_sent']}) must be in isoformat")
+    if (datetime.now() - time_sent).seconds > 10:
+        raise NotAllowed(f"The message is too old. Time sent must be within ten seconds")
+    if not 
+
+
+
+        
+
+