5.2 KiB
Retro
Writeup
For this challenge, some information was broadcasted over the names of several wifi networks:
ffffffffffffc06101df6b7d0
d16f45d14345d15545df757d1
c05501ffe1ffce2bcfcba2252
f008ebc3e683dc297bffd0df3
c0496bdf5847d16511d161ff4
d16551df4e87c05b1bffffff5
If you analyse the names, you can see that they are hexadecimal numbers, 25 characters long. Each name represents some binary information. You might also note that every name ends in a number ranging from 0 to 5: this number signifies the order in which you should look at this data.
Thus, if you take the first 24 characters of every name in order and convert the full hexadimal string to binary you get the following data:
111111111111111111111111111111111111111111111111110000000110000100000001110111110110101101111101110100010110111101000101110100010100001101000101110100010101010101000101110111110111010101111101110000000101010100000001111111111110000111111111110011100010101111001111110010111010001000100101111100000000100011101011110000111110011010000011110111000010100101111011111111111101000011011111110000000100100101101011110111110101100001000111110100010110010100010001110100010110000111111111110100010110010101010001110111110100111010000111110000000101101100011011111111111111111111111111
The bytestream represents a monochrome image, if you replace every 0 with a ██ and every 1 with a ░░, you get the following (24x24) QR-code:
░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░ ░░░░██████████████░░░░████████░░██████████████░░ ░░░░██░░░░░░░░░░██░░░░██░░██░░░░██░░░░░░░░░░██░░ ░░░░██░░██████░░██░░░░██░░░░░░░░██░░██████░░██░░ ░░░░██░░██████░░██░░████████░░░░██░░██████░░██░░ ░░░░██░░██████░░██░░██░░██░░██░░██░░██████░░██░░ ░░░░██░░░░░░░░░░██░░░░░░██░░██░░██░░░░░░░░░░██░░ ░░░░██████████████░░██░░██░░██░░██████████████░░ ░░░░░░░░░░░░░░░░░░░░░░████████░░░░░░░░░░░░░░░░░░ ░░░░████░░░░░░██████░░██░░██░░░░░░░░████░░░░░░░░ ░░░░████░░██░░░░░░██░░██████░░██████░░████░░██░░ ░░░░░░░░████████████████░░██████░░░░░░██░░██░░░░ ░░░░████████░░░░░░░░░░████░░░░██░░██████████░░░░ ░░░░██░░░░░░████████░░██░░████░░██░░░░░░░░██░░░░ ░░░░░░░░░░░░░░░░░░░░██░░████████░░░░██░░░░░░░░░░ ░░░░██████████████░░████░░████░░██░░░░██░░██░░░░ ░░░░██░░░░░░░░░░██░░██░░░░████████░░██████░░░░░░ ░░░░██░░██████░░██░░░░████░░██░░██████░░██████░░ ░░░░██░░██████░░██░░░░████████░░░░░░░░░░░░░░░░░░ ░░░░██░░██████░░██░░░░████░░██░░██░░██░░██████░░ ░░░░██░░░░░░░░░░██░░████░░░░░░██░░████████░░░░░░ ░░░░██████████████░░██░░░░██░░░░██████░░░░██░░░░ ░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░
Scanning it with a QR-code reader will give you the flag, IG{IkHouVanQR}.
Challenge name
The 'retro' name is a pointer to the homebrew programming community, where hackers actively create new games and programs for many retro gaming consoles. Representing images (commonly known as sprites) as hexadecimal numbers is a very common practice.