Tags: xor crypto
Rating:
## Challenge name: :)
### Difficulty: easy
### Description:
> Look at what I found!
XUBdTFdScw5XCVRGTglJXEpMSFpOQE5AVVxJBRpLT10aYBpIVwlbCVZATl1WTBpaTkBOQFVcSQdH
### Solution:
What we see is like base64, so we decode it.
import base64
c = 'XUBdTFdScw5XCVRGTglJXEpMSFpOQE5AVVxJBRpLT10aYBpIVwlbCVZATl1WTBpaTkBOQFVcSQdH'
c = base64.b64decode(c)
**Output**
']@]LWRs\x0eW\tTFN\tI\\JLHZN@N@U\\I\x05\x1aKO]\x1a`\x1aHW\t[\tV@N]VL\x1aZN@N@U\\I\x07G'
So we got something meaningless.
Here we need an encryption system that change hidden characters to word. The difficulty is easy, so it should be an easy one. I guess it's a repeating-XOR. We know flag starts with 'gigem{', so lets XOR 6 starting bytes with this string.
def xorbyte(s, key):
key = key * (len(s) // len(key) + 1)
output = ''
for i in range(len(s)):
output += chr(ord(s[i]) ^ ord(key[i]))
return output
xorbyte(c[:6], 'gigem{'
**Output**
':):):)'
Repeats of ':)', it seems we got the key! Lets XOR all bytes to ':)'.
xorbyte(c, ':)')
**Output**
"gigem{I'm not superstitious, but I am a little stitious.}"
