File Encryption and Decryption in C with Substitution Ciphers

Protecting sensitive data is a fundamental skill in software development, and understanding how encryption works at a low level is the perfect way to master it. This course guides you through the process of building your own file encryption and decryption tools using the C programming language. You will transition from writing basic code to developing functional command-line programs that read files, manipulate their contents using a substitution cipher, and write the secure output back to disk. What you'll learn: - Understand the core concepts of cryptography, keys, and substitution ciphers. - Manipulate text using character arrays, pointers, and ASCII values in C. - Implement robust file handling to safely open, read, write, and close files. - Build complete encryption and decryption algorithms from scratch. - Apply secure coding practices to prevent buffer overflows and handle errors gracefully. The course begins with foundational definitions of cryptographic terms and basic C file-handling functions. You will then progress through step-by-step written explanations and code walkthroughs to construct and test your cipher application. This course is designed for beginner C programmers who want to apply their skills to practical security projects; no prior cryptography experience is required. Start reading today to build your first file security program in C.