• Skip to main content
  • Skip to header right navigation
  • Skip to site footer
makerhacks-logo

Maker Hacks

Ideas, news & tutorials for makers and hackers – Arduino/Raspberry Pi, 3D printing, robotics, laser cutting, and more

  • Home
  • About
  • 3D Printing
  • Laser Cutting
  • YouTube
  • Free Arduino Course
  • Recommendations
  • Contact

Day 5: Lesson 04 – Spy Box Part 1

You are here: Home / 30 Days to Arduino Programming Course / 30 Days to Arduino Lessons / Day 5: Lesson 04 – Spy Box Part 1

Now we know how to get input from the user, we can create a cool project. 

Let’s make a Secret Spy Box with Super Fine Security*

* Not really secure

First we will accept a password to store in the Arduino volatile storage, the EEPROM memory. This means when the Arduino is turned off or reset then the password will still be in memory.

For a kind of (but not) encryption, we will use the ROT13 algorithm that “rotates” each letter of the entered password by 13. This means the password can be UNencrypted using the same method.

At the start of the sketch you will see the following:

#include <EEPROM.h> 

This is telling the Arduino editor that when we compile the sketch, we want to include the EEPROM library. This is a set of code files that give us abilities and functions not present in our own sketch.

Password Recorder Code

Arduino Lessons

  • Day Zero (What is Arduino and Why Care?)
  • Day 1: Lesson 01 – Introducing Arduino
  • Day 1 Lesson 02 – Meet Arduino Uno
  • Day 1 Lesson 03 – Breadboard a Circuit
  • Day 2 Lesson 01: Arduino Web IDE and the Structure of an Arduino C Sketch
  • Day 2 Lesson 02: Hello World!
  • Day 3: Lesson – Fun with LEDs
  • Day 4: Lesson – Magic 8 Ball & Random
  • Day 5: Lesson 01 – Arduino/C Functions and Serial Input
  • Day 5: Lesson 02 – Variable Type Conversions and Serial Input RGB LED
  • Day 5: Lesson 03 – RGB LED Color-Picker
  • Day 5: Video for Today’s Lessons
  • Day 5: Lesson 04 – Spy Box Part 1
  • Day 6: Lessons – Reading Inputs
  • Day 7: Lessons – Internet of Arduino Things
  • Day 8: Lessons – Internet of Arduino Things Part 2
  • Day 9: Lessons – Magic 8 Revisited (16×2 LCD + Tilt Switch)
  • Day 10: Lessons – Tiny Night Light (Light Sensor and ATTiny85 Programming)
  • Day 11: Lessons – Arduino Chiptune Music
  • Day 12: Lesson – 8 LED Sequence using Shift Registers
  • Day 13: Lessons – Countdown Clock with 7 Segment Display
  • Day 14: Lessons – Time.h/Arduino Clock
  • Day 15: Lessons – Ultrasonic Distance Sensors
  • Day 16: Lessons – Going Wireless!
  • Day 17: Lessons – Send and Receive IR Signals with Arduino + LEGO Power Functions!
  • Day 18: Lessons – Controlling a Canon 7D using a Hacked IR Remote and a Transistor
  • Day 19: Lesson – Arduino Remote Control MP3 Player!
  • Day 20: Lessons – Wifi with ESP8266
  • Day 21: Lessons – Wifi Data Logger with ESP8266
  • Day 22: Lessons – Arduino, Bluetooth/BLE & Android/iOS/Mac/PC
  • Day 23: Lessons – How to create your own custom Android app to control Arduino over Bluetooth
  • Day 24: Lessons – How to create your own custom iOS app to control Arduino over Bluetooth
  • Day 25: Lessons – Controlling 2x Servos with an Arduino Analog Joystick input
  • Day 26: Lessons – Controlling DC Motors, and DHT22 Temperature Sensor
  • Day 27: Lessons – Motor Controllers
  • Day 28: Lessons – Arduino 28BYJ-48 Stepper Motor Control with the ULN2003 Stepper Motor Driver
  • Day 29: Lesson – Moving Your Arduino Project Off Your Breadboard
  • Day 30: How to make the most minimal Arduino/ATmega328 breadboard circuit
  • 3D Printing
  • CNC
  • Electronics and Hardware
  • Laser Cutting
  • News and Reviews
  • Software and Programming

arduino budget cad cnc diode laser glowforge Hacks Ideas laser cutter linux Makes making python raspberry pi resin Reviews technology tips xTool Lasers

.

Maker Hacks Blog Copyright © 2026 · All Rights Reserved · Privacy Policy