5 projects: Writing CYBER SECURITY software in C language

Name: 5 projects: Writing CYBER SECURITY software in C language
Rating: 4.7 (17 reviews)

Write TOR tunnels, encryption libraries, unhackable code and file encryptors. You also learn Linux filesystem security.

Created bydr Jonas Birch, C programming ninja

Last updated 2/2025

English

English [Auto],

What you'll learn

Learn to write your own Cyber Security tools
Learn to write tools which utilise network connections.
Improve your knowledge in advanced C concepts like pointers and structs etc.
Learn about encryption, the Tor network, to write unhackable code and so on.
Learn about Linux filesystem security

Course content

1 section • 13 lectures • 8h 0m total length

Ep 01 - Writing your own Toralizer, part 1...40:00
Create a Tor-aware command line tool in C by implementing a SOCKS proxy client (v4/v5) that intercepts connect calls and routes traffic through a local Tor proxy to shield identity.
Ep 02 - ...Part two40:00
Learn how to establish a tcp connection to a proxy server, build and send a proxy request packet in c, handle return codes, and verify a successful proxy traversal.
Ep 03 - Xor encryption40:00
Explore xor encryption in C through a simple demonstration that encrypts and decrypts a single character using a key, printing hex and ascii outputs for cyber security software.
Ep 04 - Coding a real encryption library, part 1...40:00
Learn to code a real encryption library in C, including arc for init, arc for encrypt and decrypt macros, and hex output of the cipher text for cyber security projects.
Ep 05 - ...Part two40:00
Explains arc4 initialization and state management by building an arc4 structure, populating the S array and i and j, handling the key, and producing a keystream byte for encryption.
Ep 06 - ...Part three40:00
Build and understand arc4-based encryption and decryption in C, including arc for byte, keystream generation, xor operations, init and export of functions, and memory management.
Ep 07 - Linux filesystem security40:00
Explore linux file system security by mastering file permissions for user, group, and other—read, write, and execute flags, how chmod and chown work, and what 755 encodes.
Ep 08 - Coding a file encryptor, part 1...40:00
Explore Linux file system security by mastering file permissions, targets, and the chmod and chown commands, including common mode values like 644, 755, and 700, and build a file encrypter.
Ep 09 - Part two40:00
Develop a read key function that captures input from standard in without echo, using a 256-byte buffer. Toggle terminal echo with termios to disable and re-enable echo during input.
Ep 10 - Write unhackable code (safe string library), part 1...40:00
Explore building a safe string library in C by preventing stack overflow with the string n copy approach, using init, concat, and fold to manage dynamic memory.
Ep 11 - ...Part two40:00
Learn to implement a safe string library in C, adding length, copy, and concat utilities with memory management, null termination, and typecasting.
Ep 12 - Toralizer: Finishing the project, part 1...40:00
Toralizer finishing the project by turning the client into a shared library that hijacks connect to tunnel linux applications through the Tor network using ld preload and dup2.
Ep 13 - ...Part two0:48
Discover how private IP connections differ from DNS requests, how to traverse a proxy, and how to realize any command using the tool in ep 13 part two.

Requirements

This course is at intermediate-advanced level so you should have knowledge about the beginner stuff at least.

Description

8 hours of advanced C projects: Cyber Security

This is an 8 hour composite course (divided in 13 different 40min videos) containing my best content with regards to Cyber Security. You will get an in-depth knowledge in writing encryption tools, connecting to the Tor privacy network, and how to write safe, un-hackable C code by making a safe string library.

When doing all of this practically, I will explain all the necessary theory while we're coding. So there are no dense sections of heavy theory but you will still learn everything you need in order to fully understand the things we are building. While on this journey, you will also improve your knowledge of some of the more advanced features of the C language. Like how dynamic memory works, how you deal with linked lists, everything about advanced pointers, operating system functions (syscalls) as well as some binary bitwise operations, etc.

You will also learn the basics of Linux file system security and a whole lot more. And, as always, in 1080p resolution. Enjoy!

Best regards,
JB

Free preview
Do not miss out of the free preview. You can watch the entire first episode (40min!) for free. That contains the most part of one of my best C projects, the Toralizer. It is a command-line tool which lets you redirect any other Linux command through the Tor network.

Example:
bash$ toralize curl http://website-url

This will connect to the Tor privacy network and access the website. This works with any Linux command and we will code this tool from scratch to the finish line, in this course.

Prerequisites
This is not a beginner course in the C language (I have courses like that too). This is for people who already knows the basics of C and wants to take the next step to intermediate-advanced level knowledge of the C language.

This course is also for C coders who wish to know more about Cyber Security.

The author
dr. Jonas Birch has been programming the C language for more than 25 years and he's been teaching for the last 7-8 years. He has a background in the Cyber Security industry and he's a Senior network engineer. His videos are very popular (some are the highest rated courses on Udemy, in its category) and he's got a very soothing voice which is easy for the ears.

Table of Contents
00:00:00 Toralizer part 1
01:27:29 Xor encryption
01:39:09 Coding a real encryption library
04:05:41 How to install your own C library
04:15:13 Learn Linux file system security
04:44:51 Coding a file encryptor, part 1
05:37:21 Coding a file encryptor, part 2
06:05:00 Write unhackable code (safe string lib)
07:19:47 Toralizer part 2

Who this course is for:

C programmers interested in Cyber Security and who wants to do more advanced projects.