Python Cryptography Course: SHA-256, AES, RSA, and Password Security

Cryptography Fundamentals

• 💡 Cryptography is the art of hiding information, essential for safeguarding data and deterring tampering.
• 🎯 This course focuses on three core areas: hashing, symmetric encryption, and asymmetric encryption.
• 🔑 A practical command-line cryptography tool in Python will be built to demonstrate these concepts.

Hashing with SHA-256

• 🔍 Hashing is a one-way transformation that generates a unique fixed-size output (hash) from any input.
• ⚡ The SHA-256 algorithm is demonstrated, showcasing its deterministic nature and the avalanche effect where minor input changes drastically alter the output.
• ✅ Hashes are crucial for verifying file integrity, ensuring downloaded software matches the original.
• 🔒 Hashes are also used to securely store passwords instead of plain text.

Symmetric Encryption (AES)

• 🤝 Symmetric encryption uses a single secret key to both encrypt and decrypt data.
• 🔑 AES (Advanced Encryption Standard) is the go-to method, requiring a key (128-256 bits) and an Initialization Vector (IV).
• 💡 The IV is a random starting point that ensures different ciphertexts even with the same message and key.
• 🧱 Modes like GCM (Galois/Counter Mode) are used to handle data blocks and enhance security.

Asymmetric Encryption (RSA)

• 🔑 Asymmetric encryption utilizes a public key for encryption and a private key for decryption.
• 📦 The public key can be shared freely, like a padlock that anyone can use to secure a message.
• 🔓 The private key is kept secret and is the only one that can unlock and decrypt messages encrypted with its corresponding public key.
• 🛡️ Optimal Asymmetric Encryption Padding (OAEP) is used to add randomness and security to the encryption process.

Password Security

• 🚀 Password strength is assessed using the zxcvbn library, providing scores, feedback, warnings, and suggestions.
• 🔐 Bcrypt is used for securely hashing passwords, incorporating a unique salt for each password to prevent rainbow table attacks.
• ✅ The system allows for password verification by comparing a user's input attempt against the stored hash.

Building the Cryptography Toolkit

• 🛠️ A command-line interface (CLI) is developed in main.py to integrate all learned functionalities.
• 📂 Users can choose operations like hashing files, verifying integrity, AES encryption/decryption, RSA encryption/decryption, and password management.
• 🚀 The project demonstrates how these cryptographic primitives can be combined to build a practical security tool.
• 💡 The course concludes by encouraging further exploration, suggesting web interfaces with Flask and implementing digital signatures.