Tags: crypto xor
Rating:
# crypto/xorpals
Author: m0x
## Description
```
One of the 60-character strings in the provided file has been encrypted by single-character XOR. The challenge is to find it, as that is the flag.
Hint: Always operate on raw bytes, never on encoded strings. Flag must be submitted as UTF8 string.
```
Downloads: `flags.txt`
## Solution
There are 98 lines in flags.txt, and one of them is a flag that was xor'd with a single character. So this is just a brute-force exercise. For each line, xor it with a value between 0 and 255, until you find a string starting with `dam`:
```python3
#!/usr/bin/env python3
f = open(f"flags.txt", 'r')
lines = f.readlines()
for line in lines:
b = bytes.fromhex(line)
for k in range(255):
d = bytes([b[i] ^ k for i in range(len(b))])
if d[:3] == b'dam':
print(d)
break
```
```
$ ./solve.py
b'dam{antman_EXPANDS_inside_tHaNoS_never_sinGLE_cHaR_xOr_yeet}'
```
The flag is:
```
dam{antman_EXPANDS_inside_tHaNoS_never_sinGLE_cHaR_xOr_yeet}
```
