just for now

week06/hard/test.py

@@ -0,0 +1,98 @@
+#!/usr/bin/env python3
+
+import socket
+from Crypto.Cipher import AES
+from binascii import hexlify, unhexlify
+import random
+
+from Crypto.PublicKey import ECC
+HOST = 'localhost' 
+PORT1 = 20206
+PORT2 = 20306
+
+
+
+def debug_secure_channel(s1, s2, data):
+    data = data.rstrip('\n')   # remove trailing newline
+    if len(data) >= 1024:
+        print("from {} to {}: `{}...'".format(s1, s2, data[:1024]))
+    else:
+        print("from {} to {}: `{}'".format(s1, s2, data))
+
+    iv, ciphertext, mac = data.split(";")
+    assert (len(iv) == 16 * 2)                # a hexlified byte is two bytes long, the IV should be 16 bytes
+    assert (len(ciphertext) % (16 * 2) == 0)  # a hexlified byte is two bytes long, AES block size is 128 bit (16 byte)
+    assert (len(mac) == 16 * 2)               # a quite short MAC. Hint: you still don't want to brute force it!
+    print("relayed {} encrypted blocks of payload".format(len(unhexlify(ciphertext)) // AES.block_size))
+
+
+def main():
+    s1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    s1.connect((HOST, PORT1))
+    s1f = s1.makefile("rw")  # file abstraction for the sockets
+
+    s2 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    s2.connect((HOST, PORT2))
+    s2f = s2.makefile("rw")
+
+    # First step of Diffie Hellman (compare slides)
+    data = s1f.readline()
+    print("from s1 to s2: '{}'".format(data))  # you should see the newline at the end printed
+
+    p, g, X = data.split(",")
+    p = int(p)
+    g = int(g)
+    X = int(X)
+    print("p: {}  g: {}  X: {}".format(p, g, X))
+    a = random.randint(1, p-1)
+    eve_X = pow(g, a, mod=p)
+    eve_data = f"{p},{g},{eve_X}\n"
+    # # forward to Bob
+    s2f.write(eve_data)
+    s2f.flush()
+
+    # # # Receive answer (second step of DH)
+    data = s2f.readline()
+    print("from s2 to s1: '{}'".format(data))
+
+    # # # Forward received
+    # s1f.write(data)  # the data should still have a b'\n' at the end
+    # s1f.flush()
+
+    # # # Alice sends something to Bob
+    # data = s1f.readline()
+    # print("S1f {}".format(data))
+    # debug_secure_channel("Alice", "Bob", data)
+
+    # # # Forward received data to Bob
+    # s2f.write(data)
+    # s2f.flush()
+    # data = s2f.readline()
+    # debug_secure_channel("Bob", "Alice", data)
+    # print(f"get data from bob: {data}")
+    # s1f.write(data)
+    # s1f.flush()
+    # data = s1f.readline()
+    # debug_secure_channel("Bob", "Alice", data)
+    # print(f"get data from alice: {data}")
+    # # "alice sending hey bob, plz send me my f14g"
+    # s2f.write(data)
+    # s2f.flush()
+    # data = s1f.readline()
+    # print(f"get data from alice: {data}")
+    # s2f.write(data)
+    # s2f.flush()
+    # data = s2f.readline()
+    # print(f"get data from bob :{data}")
+    # s1f.write(data)
+    # s1f.flush()
+    # data = s1f.readline()
+    # print(f"get data from alice again: {data}")
+    s1f.close()
+    s2f.close()
+    s1.close()
+    s2.close()
+
+
+if __name__ == "__main__":
+    main()