Next challenge in the intermediary category is called "Hej Verden!" meaning "Hello World!". In the challenge description we are provided a .txt-file.
Downloading the file and looking into it we are provided with a very weird string that "the elfs in the attic" doesn't understand.
++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>++.>+.+++++++..+++.<<++++++++++++++.------------.>+++++++++++++++.>.+++.------.--------.<<+.Indeed this is very strange and not something I remember seeing before. What do we do? Well, let us ask good old Google:
Arh! The programming language "Brainf*ck". I remember from way back in the days when I first started learning coding in Python, one of my friends had a lot of fun with that language and telling me that the language mainly was created to be strange, weird and hard for the human brain to code in.
A quick search on the Internet and we found an interpreter we can use to make something out of the string.
Alright - it worked!
Going further in the challenge we are also provided with the weird communication of:
++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>++++++++++.-----------.<-------------------.>++++++++++++++++++++++++.--------.--------------.+++++++++.----------.-----.+++++++.++++++.-------.+++++++++++++.-------------.------.++++++++.------.+++++++++++++++++++++.-----------------.+++++++++++++.+++++++++++.This is for sure our flag, and using the same technique on that string provides us with a flag:
But isn't that too easy? Wouldn't it be funnier if we could use Python as well? Yes, you guessed it - no problem in doing so. Below is a very easy example of a Python-script converting a Brainf*ck string into something making sense.
#!/usr/bin/env python3
import brainfuck # pip install brainfuck-interpreter
bf = '++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>++++++++++.-----------.<-------------------.>++++++++++++++++++++++++.--------.--------------.+++++++++.----------.-----.+++++++.++++++.-------.+++++++++++++.-------------.------.++++++++.------.+++++++++++++++++++++.-----------------.+++++++++++++.+++++++++++.'
print(brainfuck.evaluate(bf))