> For the complete documentation index, see [llms.txt](https://ctf.zeyu2001.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ctf.zeyu2001.com/2021/dawgctf-2021/back-to-the-lab-1.md).

# Back to the Lab 1

## Problem

We've gotten hold of the plant control program, but the MELTDOWN button is locked. Figure out the flag and press the button!

Note: To run the program, you'll have to press the Run button in the upper left of the window. Press the Abort button to stop it.

Note: To run the program, you'll need some rather expensive software; look for the "community edition", it's free. It's bulky, so maybe consider installing on a VM.

Author: nb

## Solution

The source code given is a LabVIEW file. Open it using LabVIEW Community.

![](/files/-M_ELv71VczERJrn0QnJ)

For substring (0, 19), its XOR with 5 is compared with `AdrbFQC~hwZGPWK0Zop`.

For the rest, `0xA` is subtracted from it and compared with `s:)DHK8Uj&]Uj+`. The string is also reversed.

```python
first_part = 'AdrbFQC~hwZGPWK0Zop'
second_part = 's:)DHK8Uj&]Uj+'

for char in first_part:
    print(chr(ord(char) ^ 5), end='')

result = ''
for char in second_part:
    result += chr(ord(char) + 0xA)

print(result[::-1])
```

![](/files/-M_EM24gx99jY-GAo595)