BitcoinPuzzles

Lessons

Articles to learn from the start, grouped into modules. Each track is read in order, from its first module to its last.

Modules
10
Lessons
57
Reading
4h

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What is money? A brief history of exchanges

Module 1 · Lesson 1

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0 of 57 lessons read

Beginner

From zero. No prior knowledge assumed.

3 modules

Module 1

The problem of money

Why the money we use today fails, from bartering to 2008 — the problem that Bitcoin was proposed to solve.

6 lessons 24 min

  1. Lesson 1. What is money? A brief history of exchanges Before money existed, every exchange depended on an unlikely coincidence. This lesson shows what problem money solves — and why almost everything has served as money somewhere. 4 min read
  2. Lesson 2. From bartering to paper money: why money evolves Metal, minted coin, gold receipt, banknote, fiat currency. Each step solved a real problem and created a new one — including the one we are still experiencing. 4 min read
  3. Lesson 3. What gives value to money? Scarcity, trust, and consensus Gold is not valuable for being beautiful, and real currency is not valuable for being paper. This lesson lists the properties that make something function as money — and shows that the last of these is the most fragile. 4 min read
  4. Lesson 4. Inflation explained: why your money loses value Inflation is not prices rising on their own. It is money shrinking — and those who receive the new money first come out ahead. 4 min read
  5. Lesson 5. The traditional banking system: how it works (and its problems) Your balance in the app is not money stored in a safe — it is a promise. This lesson shows how banks create money and what exactly you are accepting when you use them. 4 min read
  6. Lesson 6. The 2008 crisis: the scenario that gave rise to Bitcoin A real estate market, a chain of wrapped debts, banks rescued with public money — and, five weeks after the collapse of Lehman, a nine-page document signed by a name no one knew. 4 min read

Module 2

What is Bitcoin?

Satoshi's proposal, the ledger that everyone copies, mining, and the 21 million — what the network does, and why no one needs to trust anyone.

6 lessons 24 min

  1. Lesson 1. Satoshi's proposal: what the white paper really says Nine pages, no promise of getting rich. What the document proposes, in clear Portuguese — and the specific problem it solves. 4 min read
  2. Lesson 2. How Bitcoin works, from start to finish A complete cycle in a class: someone pays, the network receives, a block closes — and the payment becomes final without anyone having approved anything. 4 min read
  3. Lesson 3. A blockchain: a ledger that everyone copies It is not a magic database. It is a list of linked blocks that anyone can verify from the first to the last — and that becomes expensive to rewrite with each new block. 4 min read
  4. Lesson 4. Mining: how new bitcoins are created and why it costs energy Miners do not solve difficult equations. They buy, with electricity, the right to propose the next block — and it is this cost that keeps the network standing. 4 min read
  5. Lesson 5. The 21 million and the halving: scarcity written in the code The limit is not someone's promise. It is a rule that each node verifies on its own, and that halves the issuance every four years. 4 min read
  6. Lesson 6. Who controls Bitcoin? The nodes, the miners, and the rules There is no CEO, no headquarters, and no button. This lesson shows where the power really lies — and why changing the rules is so difficult. 4 min read

Module 3

Using Bitcoin without getting hurt

Wallet, key, address, fee, and scam. What to do, what to never do — and what cannot be undone.

6 lessons 24 min

  1. Lesson 1. Wallets: what they really hold (it's not bitcoin) A wallet does not hold coins. It holds the key that authorizes moving them — and this difference explains almost every beginner's mistake. 4 min read
  2. Lesson 2. Private key, seed phrase, and the 12 words Twelve words in English are your entire wallet. Whoever has them has the money — and there is no second chance. 4 min read
  3. Lesson 3. Addresses: where the money goes An address is not an account. It is a disposable destination, and using a new one for each receipt is hygiene, not paranoia. 4 min read
  4. Lesson 4. Your first transaction: fee, confirmation, and change What happens between hitting "send" and the money arriving — and why there's leftover change that you didn't ask for. 4 min read
  5. Lesson 5. Self-custody vs. exchange: what "not your keys" means Leaving bitcoin on the exchange is convenient, and it is exactly the arrangement that Module 1 described — only without a central bank behind it. This lesson shows both sides of the choice. 4 min read
  6. Lesson 6. Frauds, losses, and irreversible mistakes: the survival manual There are no refunds, no support, and no "I forgot my password." The five most common ways to lose bitcoin — and the habit that prevents each one. 4 min read

Intermediate

For readers who have the basics and want the mechanism itself.

4 modules

Module 4

Numbers that become keys

Hash, curve, signature, and address. The cryptography of Bitcoin explained by what it guarantees, with mathematics only where it clarifies.

6 lessons 24 min

  1. Lesson 1. Hash: the function that only goes one way SHA-256 takes anything and returns 256 bits. It is not possible to reverse it, and this impossibility underpins half of Bitcoin. 4 min read
  2. Lesson 2. From the private key to the public key: the secp256k1 curve The public key is the private key multiplied by a fixed point. The forward process takes milliseconds — it's the reverse that no one in the world knows how to do. 4 min read
  3. Lesson 3. How an address is constructed, byte by byte Public key, two hashes, one byte of version, and a checksum. The address is the end of a short recipe that anyone can redo and verify. 4 min read
  4. Lesson 4. Digital signatures: proving without revealing A signature shows that you have the key without showing the key — and if it comes out the same twice, it's the key that falls. 4 min read
  5. Lesson 5. The size of 2^256: why no one can guess a key The key space is not large, it is absurd. This lesson measures the wall with numbers that one can imagine, and shows where it really gives way. 4 min read
  6. Lesson 6. Key formats: WIF, hex, compressed and uncompressed The same key appears in four different ways, and confusing them makes a wallet seem empty without anything actually being missing. 4 min read

Module 5

Wallets on the inside

From the seed to the derivation, and from the backup to the inheritance: what your wallet does when you are not looking.

6 lessons 24 min

  1. Lesson 1. BIP-39: how 12 words become a seed The list has 2048 words, the last one carries a conference within it, and the result is a number of 512 bits. 4 min read
  2. Lesson 2. BIP-32: deterministic wallets and derivation paths A seed, infinite keys, all recoverable. The path m/84'/0'/0'/0/0 ceases to be a spell in this lesson. 4 min read
  3. Lesson 3. BIP-44, 49, 84, and 86: why does your wallet have four accounts? The same seed in two wallets shows different balances — and almost always the blame is on the derivation pattern. 4 min read
  4. Lesson 4. Passphrase: the 13th word and the hidden wallets One more word creates an entirely new wallet from the same seed. It is the most powerful protection and the easiest to lose. 4 min read
  5. Lesson 5. Multisig: when one key is not enough Two out of three, three out of five. Distributing the authorization among keys replaces a single point of failure with a procedure. 4 min read
  6. Lesson 6. Backup that survives you: metal, redundancy, and inheritance Paper burns, cloud leaks, and memory fails. The right backup is a plan, not an object. 4 min read

Module 6

The network from the inside

UTXO, script, mempool, block, and difficulty: how the network really decides what is true.

6 lessons 24 min

  1. Lesson 1. Anatomy of a transaction: inputs, outputs, and UTXOs Bitcoin does not have a balance. It has unspent outputs, and each payment is made with whole pieces. 4 min read
  2. Lesson 2. Script: the small language that locks each coin Every exit carries a lock written in lowercase, and spending is presenting the key that it accepts. 4 min read
  3. Lesson 3. Fees, mempool, and RBF: why your transaction is stuck There is no single line and there is no attendant. There is an auction for space, and there are two ways to increase the bid afterwards. 4 min read
  4. Lesson 4. The block on the inside: header, Merkle root, and nonce Eighty bytes of header summarize thousands of transactions and answer the question that the miner is trying to solve. 4 min read
  5. Lesson 5. Difficulty: the adjustment every 2,016 blocks Doubling the mining power does not create more bitcoin. It raises the difficulty, and the clock keeps ticking at ten minutes. 4 min read
  6. Lesson 6. Run a node: verify instead of trust A common computer and a disk are enough to stop asking others what is true. 4 min read

Module 7

Bitcoin above the base layer

Lightning, Taproot, forks, privacy and what fits in the network: Bitcoin beyond the basics, including the disputes.

5 lessons 20 min

  1. Lesson 1. Lightning: instant payments on Bitcoin Channels between two parties, settled at the lower layer only when needed. Coffee paid in a second, with no block at all. 4 min read
  2. Lesson 2. Taproot and what changed in 2021 Schnorr signatures, contracts that look like ordinary payments, and a privacy gain that almost no one noticed. 4 min read
  3. Lesson 3. Forks: soft, hard, and the war of the blocks Changing the rules of a network without an owner is a political issue, and between 2015 and 2017 it was resolved publicly. 4 min read
  4. Lesson 4. Privacy: what blockchain reveals about you All transactions are public forever. Anonymity is not the default — it is work. 4 min read
  5. Lesson 5. Ordinals, tokens, and what fits (or doesn't) in the network Arbitrary data within transactions has raised the oldest question about Bitcoin: what is this network for? 4 min read

Advanced

Cryptography, key search, and what sits behind the challenges.

3 modules

Module 8

The mathematics of elliptic curves

Based on everything, now with the accounts: finite bodies, secp256k1, ECDSA — and where it breaks.

5 lessons 20 min

  1. Lesson 1. Arithmetic on a clock of prime numbers To add, multiply, and divide within a finite set. This is the arithmetic that Bitcoin truly operates on. 4 min read
  2. Lesson 2. The secp256k1 curve: points, addition, and the point at infinity y² = x³ + 7 over a finite field. This lesson adds two points with a ruler, compass, and then with a formula. 4 min read
  3. Lesson 3. Scalar multiplication and the discrete logarithm Calculating kG is quick. Discovering k from kG is the problem on which all security relies. 4 min read
  4. Lesson 4. ECDSA step by step: how a signature is calculated A nonce, two multiplications, and two numbers, r and s. This lesson calculates and verifies a complete signature. 4 min read
  5. Lesson 5. Where ECDSA breaks: repeated nonce and recovered keys Mathematics is solid; implementations are not always. A reused nonce reveals the private key with elementary algebra. 4 min read

Module 9

Key search

What does it mean to search for a key, how much does it cost, and which algorithms make the impossible just expensive?

6 lessons 24 min

  1. Lesson 1. The search space: what is a key range Searching in 2^256 is impossible; searching in 2^70 is a project. The difference between the two is the subject of this entire module. 4 min read
  2. Lesson 2. Brute force: how much it costs in time and energy One number at a time, with honest calculations of how many numbers per second and how much that costs in electricity. 4 min read
  3. Lesson 3. Baby steps and giant steps: exchanging memory for time Save half the way in the table and walk the other half. The first algorithm that beats brute force. 4 min read
  4. Lesson 4. Pollard's kangaroos: the algorithm that solves big challenges Two kangaroos jumping through the interval until they land on the same point. That's how 100-bit keys or more fall. 4 min read
  5. Lesson 5. GPU, ASIC and the difference between 2^40 and 2^70 Parallelization solves a lot but not everything. Each additional bit doubles the problem, and the list of hardware runs out before the bits do. 4 min read
  6. Lesson 6. Interval division and shared work Many people searching in the same timeframe waste almost everything. Sharing the space and proving what has been swept away is what makes a collective effort worthwhile. 4 min read

Module 10

The challenges of Bitcoin

The challenges that truly exist in blockchain, those that have already fallen, and those that this platform creates.

5 lessons 20 min

  1. Lesson 1. The challenges of 2015: the wallet with 256 addresses Someone financed 256 addresses with keys of 1, 2, 3 up to 256 bits and left them there. It's not a legend: it's on the blockchain, and it can be verified. 4 min read
  2. Lesson 2. What has already been resolved, and how each one fell The history of the solved challenges, with the method used and the time each one took. 4 min read
  3. Lesson 3. Weak keys and brain wallets: money lost due to poor passwords Whoever generated the key from a phrase lost the money to whoever thought of the same phrase. 4 min read
  4. Lesson 4. Tools: keyhunt, VanitySearch, and similar ones What each tool does, on what hardware it runs, and where each one is the right choice. 4 min read
  5. Lesson 5. The challenges of Bitcoin Puzzles: how this platform sets them up How a challenge is constructed here, what it guarantees to the participant, and how the solution is verified. 4 min read