Haxxor what?

Challenge:

I got this image of an Easter egg.

But what kind of encryption is this?!

Solution:

Given the somewhat obvious reference to XOR in the challenge title I started by using XORTool to attempt a brute-force of the key:

$ xortool -b haxxorwhat

The most probable key lengths:
 2:   8.7%
 4:  13.2%
 6:   7.3%
 8:  19.6%
10:   6.4%
12:   9.1%
16:  13.2%
20:   6.4%
24:   9.3%
32:   6.9%
Key-length can be 4*n
256 possible key(s) of length 8:

haxxors!
i`yynsr
jczzmpq#
kb{{lqp"
le||kvw%
...
Found 0 plaintexts with 95%+ valid characters

The first possible key of haxxors! looked promising so I loaded the haxxorwhat file into CyberChef, entered the key into a XOR operation and CyberChef auto-recognized the output as a PNG image file:

The accepted flag was, he2021{r34l_x0r_h4xx0r}