Description

Can you get the real meaning from this file?

Process / Notes

wget the file
file shows its ASCII text
The tags on the challenge indicate base64 and Caesar cipher
Both cat and strings display the same thing
Trying base64 first
Looks like we’re getting somewhere
Using the inbuilt Neo Vim rot13 cipher with g??
That didn’t seem to help. What about rot13, then base64?
No luck
base64 decode nor encode seemed to do anything. What about encode first?
base64 -d the original text from the file, then trying to base64 -d it AGAIN
Now it’s starting to look like a pictoCTF flag with the “{}” present
Now going to try g??
Nothing with rot13. But online it looks like there’s a built in tr command line command that may help
The tr command will:
- Translate, squeeze, and/or delete characters from standard input, writing to standard output. STRING1 and STRING2 specify arrays of characters. ARRAY1 and ARRAY2 that control the action
There’s an example using regex expressions for custom offsets on Stack Overflow
With w and c 6 characters apart, going to try that in my expression
Wait, that’s the wrong combination of characters to look at!
- echo 'string' | tr '[a-zA-Z]' '[g-za-fG-ZA-F]' is not the right offset
I need ‘j’ to become ‘p’
With the [g-za-fG-ZA-F] rotation, the flag is revealed

21 minutes 9 seconds to complete

Messages may be double, triple, or more encoded, even in the same manner, as with the base64 encoding
How to use tr to rotate characters encrypted with a Caesar cipher