initial commit

CTF/W1seGuy/decrypt.py

@@ -0,0 +1,38 @@
+import itertools
+
+def xor_decrypt(hex_encoded, key):
+    data = bytes.fromhex(hex_encoded)
+    decrypted = ''
+    for i in range(len(data)):
+        decrypted += chr(data[i] ^ ord(key[i % len(key)]))
+    return decrypted
+
+def recover_xor_key(hex_encoded, known_start="THM{", known_end="}"):
+    data = bytes.fromhex(hex_encoded)
+
+    # Step 1: Recover partial key from known prefix
+    partial_key = [chr(data[i] ^ ord(known_start[i])) for i in range(len(known_start))]
+
+    # Step 2: Brute-force remaining characters of 5-character key
+    charset = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
+    key_length = 5
+    unknown_length = key_length - len(partial_key)
+
+    for combo in itertools.product(charset, repeat=unknown_length):
+        key = ''.join(partial_key + list(combo))
+        decrypted = xor_decrypt(hex_encoded, key)
+        if decrypted.startswith(known_start) and decrypted.endswith(known_end):
+            return key, decrypted
+
+    return None, None
+
+if __name__ == "__main__":
+    hex_encoded = "272f0549124206245c16361f3c731607532b590132093a01031f2b315a370113310217011f07401f"
+    key, message = recover_xor_key(hex_encoded)
+
+    if key:
+        print("✅ Found key:", key)
+        print("🔓 Decrypted message:", message)
+    else:
+        print("❌ Key not found.")
+