# Hidden Flag
## Description
This image seems wrong.....did Keith lose the key __again__?
[chall.png](chall.png)
## Solution
An error occured when opening the file.
The hexdump of the file give me an interesting line in the last line.
![alt text](hexdump.png)
However, I don't have any idea where to use the key.
After trying a lot of different way to analyse the file, the [xortool](https://github.com/hellman/xortool) catch my eye.
![alt text](xortool.png)
It xor the whole file with different possible key.
The first key it use is literally invisible, and the first [file](xor.png) of the output give us the flag
![alt text](xor.png)
```hsctf{n0t_1nv1s1bl3_an5m0r3?_39547632}```