Class 6
Class 6 – Cryptography
Class Material: Week 3 day 2 – Cryptography
This lecture expands on modern cryptographic techniques and their practical use across various industries. It introduces symmetric and asymmetric encryption, hashing, digital signatures, and the wide range of applications for cryptography in everyday digital security.
Key Topics Covered:
Modern Cryptography Fundamentals
Modern cryptography uses mathematics and computing to secure digital communication. It focuses on principles such as confidentiality, integrity, authentication, and non-repudiation. It forms the backbone of secure systems used in banking, communication, and data protection.
Real-World Applications
Cryptography powers secure messaging apps (WhatsApp, Signal), online banking (SSL/TLS), encrypted websites (HTTPS), cloud storage protection, digital signatures (e.g., on PDFs and emails), two-factor authentication, VPNs, and even military-grade communications.
Types of Cryptographic Techniques
Symmetric Encryption (e.g., AES): Uses one key for both encryption and decryption. Ideal for fast, bulk encryption.
Asymmetric Encryption (e.g., RSA): Uses a public and private key pair. Common in secure communication and digital signatures.
Hashing (e.g., SHA-256): Converts data into a fixed-size string for verifying integrity. One-way and irreversible.
Digital Signatures: Provide authentication, integrity, and non-repudiation. Used in software validation, contracts, and blockchain.
Cryptographic Tools & Use Cases
OpenSSL: Used for AES encryption/decryption and certificate generation.
Hashcat: Password recovery tool that supports MD5, SHA1, and WPA cracking.
Cryptool (cttool): Offers both classical and modern cipher tools for practice.
GPG: Standard tool for file encryption and digital signature verification.
CyberChef: A browser-based platform for experimenting with cryptographic transformations.
This session gives a strong foundation in applied cryptography. By covering both theoretical concepts and real-world tools, students gain the skills to understand, implement, and analyze secure systems in practical cybersecurity contexts.