# Reverse Engineering

| Challenge                    | Link                          |
| ---------------------------- | ----------------------------- |
| Flag Generator (4 solves) 🥈 | [Here](#free-play-495-points) |

## Flag Generator (4 solves)

### Description

\-

### Solution

Should be unintended, since the key length is only 6. I brute each 3 bytes and get the flag by guess it :p . Here is script i used to bruteforce the possible key and value

```python
from itertools import permutations
import string

def check(hello):
	return all(c in string.printable for c in hello)

ct = [0x7d, 0x9c, 0x73, 0xb4, 0xc, 0x8e, 0x4e, 0x99, 0x71, 0xe0, 0xb, 0x9e, 0x63, 0xd8, 0x75, 0xef, 0x50, 0xa3, 0x20, 0xde, 0x42, 0xf4, 0x4d, 0x8c, 0x22, 0xdf, 0x42, 0xe1, 0x4d, 0x92, 0x30, 0x8c, 0x3c]

list_poss = [i for i in range(256)]

for i in permutations(list_poss, 3):
	poss = []
	for j in range(0,len(ct)-5,6):
		tmp = bytes([(ct[j+3]^i[0])]) # tmp = bytes([(ct[j]^i[0])])
		tmp += bytes([ct[j+4]^i[1]]) # tmp += bytes([ct[j+1]^i[1]])
		tmp += bytes([ct[j+5]^i[2]]) # tmp += bytes([ct[j+2]^i[1]])
		try:
			tmp = tmp.decode()
			if(check(tmp)):
				poss.append(tmp)
		except Exception as e:
			break
	if(len(poss) == 5):
		print(i, poss)
```

Flag : l1n34r\_4lg3bruhhh\_1s\_sup3r\_fun!!!


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://kos0ng.gitbook.io/ctfs/write-up/2023/bsides-indore/reverse-engineering.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.