Lesson 5

πŸ” Keys, Wallets & Sovereignty

Your keys, your Bitcoin, your future

⏱️ 45 min πŸ“Š Intermediate πŸš€ Build: PRF Wallet on Citrea

🎯 Keys, Wallets & Sovereignty

45 minutes to true Bitcoin self-custody. You'll set up a PRF wallet on Citrea using WebAuthn passkeys β€” no seed phrases to lose, biometric security, and full control of your keys = your Bitcoin = your future.

πŸ”‘
Not Your Keys, Not Your Coins

PRF + WebAuthn lets you derive deterministic keys from hardware/biometric passkeys without ever exposing a seed phrase.

πŸš€ What You'll Build

A PRF wallet on Citrea: register with Face ID / YubiKey, derive spending keys on-the-fly, sign transactions, and hold testnet BTC. Your keys stay in your device β€” true sovereignty.

πŸ“š Quick Concepts

  • Private Keys: The secret that controls your funds (ECDSA secp256k1).
  • PRF (WebAuthn Pseudo-Random Function): Derives encryption/spending keys directly from your biometric/hardware authenticator.
  • WebAuthn: Passwordless, phishing-resistant standard used by Apple, Google, YubiKey.
  • Self-Custody: You and only you control the keys.

πŸ”¨ Build Steps

  1. Visit the Citrea PRF Wallet dApp.
  2. Register passkey (Face ID / security key).
  3. Derive your first spending key using PRF extension.
  4. Fund the wallet with testnet sats.
  5. Send a test transaction β€” you just proved self-custody on Bitcoin L2.

οΏ½ The Aha Moment: Find a Valid Hash

Let's experience what miners do. Try to find a hash starting with "0000". You'll see why mining is hard!

⛏️ Try It: Mining Simulator
Interactive
⚑
Why It's Hard

Real Bitcoin mining requires finding hashes with 19+ leading zeros. That's trillions of attempts per second!

πŸ“Š Difficulty Adjustment

Every 2,016 blocks (~2 weeks), Bitcoin automatically adjusts the puzzle difficulty to maintain the 10-minute average.

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More Miners Join

Blocks come faster β†’ Difficulty increases β†’ Back to 10 minutes

πŸ“‰

Miners Leave

Blocks slow down β†’ Difficulty decreases β†’ Back to 10 minutes

🎯
Why This Matters

This self-regulating mechanism ensures predictable issuance regardless of how much computing power joins or leaves the network.

⚑ The Halving

Every 210,000 blocks (~4 years), the block reward is cut in half. This creates increasing scarcity over time.

πŸ“…Halving Timeline
2009: 50 BTC per block
2012: 25 BTC per block
2016: 12.5 BTC per block
2020: 6.25 BTC per block
2024: 3.125 BTC per block (current)
~2140: Last satoshi mined, 21M cap reached

πŸ›οΈ Austrian Economics Corner

πŸ“š

Unforgeable Costliness

Gold is valuable partly because extracting it requires real resources. You can't fake the mining process. Bitcoin's Proof-of-Work creates the same unforgeable costlinessβ€”you cannot fake the energy expenditure needed to mine Bitcoin.

This is why fiat currency fails as sound money: governments can print unlimited amounts at near-zero cost. Bitcoin's mining cost creates a floor price.

"What desirable property should the money commodity have? It should be costly to produce." β€” Nick Szabo, Cryptographer
⚑
Thermodynamic Money

Bitcoin converts electrical energy into monetary security. This creates a physical anchor between the digital realm and real-world resources.

🌍 Energy & Environment

Bitcoin mining is often criticized for energy use. Here's the nuanced reality:

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Energy Seeking

Miners seek the cheapest energyβ€”often stranded renewables or wasted flare gas that would otherwise be unused.

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Security Cost

The energy secures a $1+ trillion network. Banks, gold mining, and traditional finance also consume massive resources.

🏊 Mining Pools

Solo mining is like buying one lottery ticket. Pools combine hash power and share rewards proportionally.

🀝
How Pools Work

Thousands of miners contribute hash power. When the pool finds a block, rewards are distributed based on each miner's contribution. Smaller, steadier income vs. rare large payouts.

🎬

Watch: Inside a Bitcoin Mining Operation

12:00

🧠 Teach Satoshi

Before the quiz, prove you understand by explaining the concept. Satoshi AI will challenge your thinking until you achieve mastery.

πŸ“ Check Your Understanding

Complete the quiz to unlock the next lesson. You need 80% to pass.

Continue to Lesson 6: Bitcoin Layer 2 & Citrea