iniciando trab 4

trabalho4/tgs.py

@@ -0,0 +1,77 @@
+import socket
+from common import *
+import socket
+from AES import AESCipher
+import os
+
+HOST = "127.0.0.1"
+PORT = TGS_PORT
+
+def process_message(message):
+    print(message)
+    message = message.split("||")
+
+    if message[0] == "request":
+        """
+            T_c_tgs = {ID_C + T_R + K_c_tgs}K_tgs
+
+        M3 = [{ID_C + ID_S + T_R + N2}K_c_tgs + T_c_tgs]
+        M4 = [{K_c_s + T_A + N2}K_c_tgs + T_c_s]
+            T_c_s = {ID_C + T_A + K_c_s}K_s
+        """
+        body = message[1].split(",")
+        K_tgs = C_K_tgs
+
+        M3 = body[0]
+        M3 = M3.split(",")
+        M3_inner = M3[0]
+        T_c_tgs = body[1]
+        print('T_c_tgs', type(T_c_tgs), T_c_tgs)
+
+        M3_AES = AESCipher(K_tgs)
+        T_c_tgs = M3_AES.decrypt(T_c_tgs)
+        T_c_tgs = T_c_tgs.split(",")
+        ID_C = T_c_tgs[0]
+        T_R = int(T_c_tgs[1])
+        K_c_tgs = eval(T_c_tgs[2])
+
+        M3_inner_AES = AESCipher(K_c_tgs)
+        M3_inner = M3_inner_AES.decrypt(M3_inner)
+        M3_inner = M3_inner.split(",")
+        ID_S = M3_inner[1]
+        N2 = M3_inner[3]
+
+        # generate M4
+        K_c_s = os.urandom(16)
+        T_A = 600 if T_R > 600 else T_R
+        T_c_s = f"{ID_C},{T_A},{K_c_s}"
+
+        K_s = C_K_s
+        T_c_s_AES = AESCipher(K_s)
+        T_c_s = T_c_s_AES.encrypt(T_c_s)
+
+        M4_inner = f"{K_c_s},{T_A},{N2}"
+        M4_inner_AES = AESCipher(K_c_tgs)
+        M4_inner = M4_inner_AES.encrypt(M4_inner)
+
+        M4 = f"{M4_inner},{T_c_s}"
+        return M4
+
+def main():
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+        s.bind((HOST, PORT))
+        s.listen()
+        while True:
+            conn, addr = s.accept()
+            with conn:
+                print(f"Connected by {addr}")
+                all_data = ""
+                data = conn.recv(4096)
+                all_data += data.decode()
+
+                response = process_message(all_data)
+
+                conn.sendall(response.encode())
+
+if __name__ == "__main__":
+    main()