Foundations of Classical Cryptography and Number Theory

How do we keep digital information secure in an interconnected world? The answer lies in the elegant intersection of mathematics and classical cryptography. This text-based course guides you through the core algebraic concepts and number theory that power modern security protocols. You will transition from understanding basic historical ciphers to analyzing the mechanics of robust public-key cryptography. What you will learn: Understand foundational algebraic concepts, modular arithmetic, and prime numbers essential for security; Analyze classical ciphers, their structural vulnerabilities, and why they fail against modern cryptanalysis; Explore the mathematical mechanics of the RSA algorithm and Diffie-Hellman key exchange; Evaluate the practical implementation challenges of cryptographic schemes, including side-channel vulnerabilities; Practice decrypting a stream cipher through written step-by-step cryptanalysis exercises; Learn about modern cryptographic trends, including the transition toward post-quantum security standards. You will start with essential definitions and foundational mathematics before moving on to historical encryption techniques. From there, you will read through the step-by-step logic of public-key systems and complete practical written exercises to test your code-breaking skills. This course is designed for beginners in security, software development, or mathematics, requiring no prior background in cryptography. Start reading today to unlock the mathematical secrets behind secure data transmission.