Help Needed with a CTF Challenge: Resistor Color Code Puzzle

beginners
1

Hi everyone!

I’m currently working on a CTF challenge that involves a breadboard setup with several resistors, and I believe the key to solving the puzzle lies in interpreting the resistor color codes.

My initial thought was to convert the resistor values into ASCII characters, as CTF flags typically follow a format like ctf_{something}. I started decoding the resistor values, and the beginning looks promising, but the rest doesn’t seem to make much sense.

Here’s what I’ve done so far:

  • 9903 → c
  • 1160 → t
  • 1020 → f
  • 191, 191 → Interpreted as 190, and in parallel, this gives 95 (but unsure how to interpret this further).
  • 5703, 5703 → (Not sure what to do here)
  • 241, 241, 241, 241, 241 → In parallel, this gives 48.
  • 1020 → f
  • 7603 → L

So far, it seems like the first part spells out ctf_, but I’m struggling with the remaining values. Based on typical CTF formats, I’m expecting a flag structure like ctf_This_i5_the_Flag_forma7 or something similar.

Any ideas or suggestions on how to interpret the remaining resistor values or if I’m missing something? I’d greatly appreciate any help or pointers in the right direction!

Thanks in advance!

futile
futile1755×636 146 KB

2

Anyone with an idea?

3

I’m unclear on what exactly a CTF is. It’s hard to have ideas about unknowns.

4

Ah, you’re absolutely right. I’ll explain briefly. CTF stands for Capture the Flag. The aim of the challenge is to find a flag or a password with which you can solve the challenge. I’m not super familiar with electronics and can’t find the complete solution. There are a lot of people here with expertise, so I was hoping someone might have another tip.

5

Ok, it’s a bit messy with a mix of 4 to 5 band (all seem to be 5-10% tolerance, silver or gold). Are the tolerance values ignored? If it’s just a case of the values then take the two in series, for instance, add, and convert back to color codes?

The 95 would be white, green, black (95ohms, 5-10% tolerance).
The series could be 1140K so, brown, brown, yellow, orange gold for 1.14 mOhm.
The 48 Ohms from the 240s in series would be yellow, grey, black and gold (for the same tolerance).

EDIT:
95 is the underscore _ char
1.14 lower case r
48 is 0 (zero)
102 ohms is lowercase f
76 K uppercase L

6

Heh. And that’s basically back to where you were :slight_smile:

7

Wow, that helpdesk a lot! It was ctf_r0fL :grin:
Thank you <3