BuckeyeCTF2025 misc/Minecraft

Redstone can do so many things.

Observations

The challenge comes as a Minecraft world to import. After importing it into my game, I launch the world.

Upon spawning, I find myself in front of a massive redstone circuit:

The redstone circuit is connected to a lamp that needs to be turned on.

The circuit is made up of 18 triangles, each powered by 8 levers:

The 8 levers remind me of the 8 bits in a byte.

Strategy

To light up the lamp, all the redstone outputs from the triangles must be powered.

For a triangle’s output redstone to be on, all the redstone torches on top must be off, and all the redstone torches attached to the iron blocks must be on:

So, the goal is to adjust the levers so that:

• the torches on the upper row are off, and
• the ones attached to the iron blocks are on.

Once all levers are correctly positioned, the lamp lights up:

ASCII Conversion

Now that the lamp is on, we can record the lever positions:

• Lever up (unpressed) = 0
• Lever down (pressed) = 1

Each triangle contains 8 levers, representing 8 bits, which corresponds to one ASCII character.

By converting each 8-bit sequence into ASCII, we get:

01100010 : b
01100011 : c
01110100 : t
01100110 : f
01111011 : {
00111000 : 8
00110000 : 0
00110000 : 0
00110001 : 1
00110011 : 3
00110100 : 4
01001110 : N
00110001 : 1
00110000 : 0
00110110 : 6
00110001 : 1
01000011 : C
01111101 : }

The flag is bctf{800134N1061C}.

Written by Hiwiks.