Beginner

Goal Understand entropy and randomness as the foundation of cryptographic security, learn binary encoding (Base64, hex), and combine everything into practical encrypted workflows with best practices. Prerequisites: Week 2b (Symmetric Encryption) This is Part 3 of 3 - Covers entropy, encoding, workflows, and best practices. 1. Entropy and Randomness: The Foundation of Security What Is Entropy? Entropy is a measure of unpredictability (randomness). In cryptography: High entropy = Truly random, unpredictable Low entropy = Patterns, predictable Why it matters: ...

Goal Understand the public-key cryptography revolution and generate your first GPG keypair. This is the foundation for everything else in the course. Prerequisites: Week 2 (Cryptography Fundamentals) This is Part 1 of 4 - Covers history, concepts, and key generation. Introduction: The Public Key Revolution Week 2 taught you symmetric encryption - Alice and Bob share the same secret key. But how do they exchange that key securely? The problem: ...

Goal Master practical GPG operations: understanding your keyring, encrypting files for yourself and others, and creating digital signatures that prove authorship and integrity. Prerequisites: Week 3a (GPG Introduction & Key Generation) This is Part 2 of 4 - Covers keyring management, encryption operations, and signatures. 1. Understanding Your GPG Keyring List All Keys # List public keys gpg --list-keys # Output: pub rsa4096 2025-10-14 [SC] [expires: 2027-10-14] ABCD1234ABCD1234ABCD1234ABCD1234ABCD1234 uid [ultimate] Alice Cypherpunk <[email protected]> sub rsa4096 2025-10-14 [E] [expires: 2027-10-14] Key anatomy: ...

Goal Master public key distribution methods: exporting and importing keys, using keyservers safely, and understanding the Web of Trust model for decentralized identity verification. Prerequisites: Week 3b (Encryption & Signatures) This is Part 3 of 4 - Covers key distribution, keyservers, and web of trust. 1. Public Key Distribution and Import Export Your Public Key # Export in ASCII armor (shareable format) gpg --armor --export [email protected] > alice-public-key.asc # View the exported key cat alice-public-key.asc Output: ...

Goal Complete your GPG mastery with key lifecycle management (rotation, revocation, backup), practical email encryption, and understanding when to use modern alternatives like age for simpler use cases. Prerequisites: Week 3c (Key Distribution & Web of Trust) This is Part 4 of 4 - Covers key management, email encryption, and modern alternatives. 1. Key Management: Rotation, Revocation, and Backup Extending Key Expiration Your key expires in 2 years. Before expiration: ...

Real-World Examples: Why Privacy Matters “I have nothing to hide” assumes the world is fair, rules never change, and your data will never be used against you. History—and current events—prove otherwise. This page documents real incidents where lack of privacy caused tangible harm. These aren’t hypotheticals. They happened to real people. Physical Security Threats Bitcoin and Cryptocurrency Holders When you publicly hold valuable assets, you become a target. The documented attacks are sobering: ...