user login

requirements.txt

@@ -1 +1,2 @@
 pycryptodome
+pydh

server/netwrapper.py

@@ -1,22 +1,133 @@
 #!/usr/bin/env python3
+import json
+from base64 import b64encode, b64decode
+import pyDH
+from Crypto.Cipher import PKCS1_OAEP
+from Crypto.PublicKey import RSA
+from Crypto.Cipher import ChaCha20
+from Crypto.Random import get_random_bytes
+
+from netsim import network_interface
+from server.server import Server
+
 
 class NetWrapper:
 
-    def __init__(self, publicKey: str, privateKey: str, cipherKey: str = ""):
-        self.publicKey = publicKey
-        self.privateKey = privateKey
-        self.cipherKey = cipherKey
+    def __init__(self, clientPublicKey: dict, serverPrivateKey: str, serverInstance: Server):
+        self.clientPublicKey = clientPublicKey
+        self.currentClientPublicKey = "".encode('UTF-8')
+        self.serverPrivateKey = serverPrivateKey
+        self.cipherkey = "".encode('UTF-8')
+        self.network = network_interface('./', 'A')
+        self.clientAddr = ""
+        self.currentUser = ""
+        self.serverInstance = serverInstance
 
-    def identifyServer(self,message: bytes):
-        #Message is coded with Server RSA public key in string byte format
-        #Create network_interface
-        pass
+    def serverIdentify(self, msg: bytes) -> None:
+        incommingJson = json.loads(msg.decode('UTF-8'))
+        self.clientAddr = incommingJson['source']
+        self.currentUser = incommingJson['username']
+        self.currentClientPublicKey = self.clientPublicKey[self.currentUser]
+        myrsakey = RSA.import_key(self.serverPrivateKey)
+        mycipher = PKCS1_OAEP.new(myrsakey)
+        retmsg = mycipher.decrypt(b64decode(incommingJson['message'])).decode('UTF-8')
+        rsakey = RSA.import_key(self.currentClientPublicKey)
+        cipher = PKCS1_OAEP.new(rsakey)
+        identMsg = json.dumps(
+            {'type': 'IDY', 'source': self.network.own_addr,
+             'message': b64encode(cipher.encrypt(retmsg.encode('UTF-8')))}).encode(
+            'UTF-8')
+        self.network.send_msg(self.clientAddr, identMsg)
 
-    def identifyCleint(self):
-        pass
+    def sendMessage(self, message: bytes) -> None:
+        cipher = ChaCha20.new(self.cipherkey, get_random_bytes(12))
+        ciphertext = cipher.encrypt(message)
+        nonce = b64encode(cipher.nonce).decode('UTF-8')
+        ct = b64encode(ciphertext).decode('UTF-8')
+        sendjson = json.dumps({'type': 'CMD', 'source': self.network.own_addr, 'nonce': nonce, 'message': ct}).encode(
+            'UTF-8')
+        self.network.send_msg(self.clientAddr, sendjson)
 
-    def sendMessage(self):
-        pass
+    def keyExchange(self) -> None:
+        dh = pyDH.DiffieHellman()
+        rsakey = RSA.import_key(self.currentClientPublicKey)
+        cipher = PKCS1_OAEP.new(rsakey)
+        mypubkey = b64encode(cipher.encrypt(str(dh.gen_public_key()).encode('UTF-8')))
+        jsonmsg = json.dumps({'type': 'DH', 'source': self.network.own_addr, 'message': mypubkey}).encode('UTF-8')
+        self.network.send_msg(self.clientAddr, jsonmsg)
+        decodedmsg = {'source': '', 'type': ''}
+        while not (decodedmsg['source'] == self.clientAddr and  decodedmsg['type'] == 'DH'):
+            status, msg = self.network.receive_msg(blocking=True)
+            if not status:
+                raise Exception('Network error during connection.')
+            decodedmsg = json.loads(msg.decode('UTF-8'))
+        myrsakey = RSA.import_key(self.serverPrivateKey)
+        mycipher = PKCS1_OAEP.new(myrsakey)
+        serverpubkey = int(mycipher.decrypt(b64decode(decodedmsg['message'])).decode('UTF-8'))
+        self.cipherkey = dh.gen_shared_key(serverpubkey).encode('UTF-8')
 
-    def recieveMessage(self):
-        pass
+    def login(self) -> bool:
+        b64 = {'source': '', 'type': ''}
+        while not (b64['source'] == self.clientAddr and  b64['type'] == 'AUT'):
+            status, msg = self.network.receive_msg(blocking=True)
+            if not status:
+                raise Exception('Network error during connection.')
+            b64 = json.loads(msg.decode('UTF-8'))
+        try:
+            retnonce = b64decode(b64['nonce'])
+            retciphertext = b64decode(b64['message'])
+            retcipher = ChaCha20.new(self.cipherkey, nonce=retnonce)
+            plaintext = retcipher.decrypt(retciphertext).decode('UTF-8').split(' ')
+            linsuccess = (not (len(plaintext) != 3 or plaintext[0] != "LIN" or plaintext[1] != self.currentUser)) and self.serverInstance.login(plaintext[1],plaintext[2])
+            if linsuccess:
+                message = "OK".encode('UTF-8')
+            else:
+                message = "ERROR".encode('UTF-8')
+            cipher = ChaCha20.new(self.cipherkey, get_random_bytes(12))
+            ciphertext = cipher.encrypt(message)
+            nonce = b64encode(cipher.nonce).decode('UTF-8')
+            ct = b64encode(ciphertext).decode('UTF-8')
+            sendjson = json.dumps({'type': 'AUT', 'source': self.network.own_addr, 'nonce': nonce, 'message': ct}).encode(
+              'UTF-8')
+            self.network.send_msg(self.clientAddr, sendjson)
+            return linsuccess
+        except Exception:
+            print("Incorrect decryption")
+
+    def initClientConnection(self, msg: bytes) -> bytes:
+        try:
+            self.serverIdentify(msg)
+            self.keyExchange()
+            success = self.login()
+            if success:
+                return b"LINOK"
+            else:
+               self.logout()
+        except Exception:
+            self.logout()
+
+    def recieveMessage(self) -> bytes:
+        status, msg = self.network.receive_msg(blocking=True)
+        if not status:
+            raise Exception('Network error during connection.')
+        if not self.clientAddr:
+            return self.initClientConnection(msg)
+        else:
+            return self.recieveEncryptedMessage(msg)
+
+    def logout(self) -> None:
+        self.clientAddr = ""
+        self.cipherkey = "".encode('UTF-8')
+        self.currentClientPublicKey = "".encode('UTF-8')
+        self.currentUser = ""
+
+    def recieveEncryptedMessage(self, msg: bytes) -> bytes:
+        try:
+            b64 = json.loads(msg)
+            retnonce = b64decode(b64['nonce'])
+            retciphertext = b64decode(b64['message'])
+            retcipher = ChaCha20.new(self.cipherkey, nonce=retnonce)
+            plaintext = retcipher.decrypt(retciphertext)
+            return plaintext
+        except Exception:
+            print("Incorrect decryption")