week06

week05/hard/test.py

@@ -0,0 +1,36 @@
+import base64
+import random
+from Crypto.Cipher import AES
+
+KEY = random.randbytes(16)
+# KEY =b'\xaab\xa65z"\xac\xb1,a\xff1\xdb6}\xb0' # The key should match the server's key
+IV = b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"  # The IV can be random
+
+def pkcs7(message: bytes, block_size: int = 16) -> bytes:
+    gap_size = block_size - (len(message) % block_size)
+    return message + bytes([gap_size] * gap_size)
+
+
+def cbc_mac(message: bytes, iv: bytes, key: bytes) -> bytes:
+    cipher = AES.new(key, AES.MODE_CBC, iv)
+    message = pkcs7(message)
+    last_block = cipher.encrypt(message)[-16:]
+    return last_block
+
+# Craft the message
+message = b"type=recrets&number=1337"
+
+# Calculate the MAC
+mac = cbc_mac(message, IV, KEY)
+
+# Base64 encode the message, IV, and MAC
+encoded_message = base64.b64encode(message).decode('utf-8')
+encoded_iv = base64.b64encode(IV).decode('utf-8')
+encoded_mac = base64.b64encode(cbc_mac(message, IV,KEY)).decode('utf-8')
+
+# Final request to send
+final_message = f"{encoded_message};{encoded_iv};{encoded_mac}"
+
+print(final_message)
+
+# MAC verification failed: expected afb7f5f307ea507b631d964e089a820a, got a0b0b48844a7deaf9d917a5f11ae0359