#This is a quick and dirty writeup 
Hi,
The given file (unknown) is an ELF 64-bit LSB executable stripped .A binary without anti-debug tricks or obfuscation .
unknown is an executable. When we run it, it returns 'Try again.'
I imported the binary file into IDAPro then, with a top-down looking at the assembly code i noticed that the binary takes something as an argument and when we give itan argument it returns 'Still nope.'
To find the flag we have to find the correct input .
Our assembly code show us these things :
1- len(input) == 56
2-there is a loop that encrypt our characters and  check each of it with an encrypted character, if encrypt(input[i]) !=encrypt(flag[i]): mov     cs:dword_603084, 1
3- if(dword_603084 ==1): failed
it can be quicky solved by a brute force attack . check my python script :)
