The challenge provides a zip file, which has 3 files - assem.c, assem.s and out.txt. charasm function called in the assem.S,
This function returns its first parameter.
This c function takes a string input:
not operation is performed in the bytes at odd positions bytes at even position is written as same(since charsm function returns the first parameter of its input)
So, Not operation should be performed on bytes at odd positions. The resulting hexadecimal value when converted into ASCII will give the output:
And that’s our flag!