Bitcoins Genesis 1.What is the denition of a cryptocurrency? 2.What was the goal of the Cypherpunks? How does Bitcoin t into that goal? ((Its okay not to know).) 3.What is a double spend attack? Identity on the Blockchain 1.What is the denition of a private key? 2.What is the denition of a public key? 3.What are purposes of each? 4.True or false: The public key is chosen at random, and the private key is generated from the public key (Its okay not to know). Bonus: Why is this the case? What could go wrong if the process were the other way around?

Transactions on the Blockchain 1.What three things need to be true about a transaction for it to be considered valid? 2.What is the UTXO model? What analogy is used to better understand the model? Record-Keeping via the Blockchain 1.Who stores the transaction history? 2.What is the denition of a blockchain data structure? 3.Why is it useful for storing information in this type of distributed data store? Consensus: Proof-of-Work 1.What is the denition of consensus?

2.Why do participants in the Bitcoin network need to come to consensus?

3.Describe each of the stages of consensus mentioned in lecture (not including Proof-of-Work), and identify the aw with each stage? Hint: What is a Sybil attack? What requirements of Bitcoin prevent these from being easily prevented? 4.What is Proof-of-Work? What makes this consensus algorithm capable of resisting attackers? 5. Bonus: What assumption does Proof-of-Work make about the amount of mining power controlled by adversaries? What kind of problem do participants in the consensus process need to solve in order to submit a block to the network? Summary How does Bitcoin accomplish in a decentralized manner what banks do centrally? Answer this question for Identity, Transactions, Record Keeping, and Consensus. Give a denition for each of the below terms, and connect them to Bitcoin. Decentralized Distributed Bonus: How is distributed dierent from decentralized? (Its okay not to know yet.) Anonymous Immutable Trustless Global

Wallets What is the purpose of a wallet? What two types of wallets are there? What distinguishes these wallets? Whats a convenient way to add a bit of protection to our brain wallet key? What are the dierences between a centralized and decentralized exchange? What is the difference between cold storage and hot storage? How would an exchange decide how much bitcoin to store in hot storage vs. cold storage?

Wallet Mechanics What is an SPV node? What are the benets and losses of using SPV? What is the naive way to store multiple keys? What is the name of the wallet to improve key generation eciency? Which kinds of wallets here are suited for which kinds of users? What is secret sharing and how does it differ from Multi-sig? What are Proof of Reserve, Proof of Liabilities and Proof of Inclusion? How do they work and what are the purposes of using them? Mining Incentives 1.What are the steps in a mining recipe? 2.What are the four key components to calculating MINING_PROFIT? 3.What is the purpose of the block reward? 4.What is the purpose of transaction fees? 5.What constitute xed costs? What constitute variable costs? 6.What does ASIC stand for? Real World Mining 1.What are mining pools? What are the advantages and disadvantages that they bring about? 2.What is the typical mining hardware, strategies, methods that used in Bitcoin mining? 3.How do mining pools approximate computational power expended towards solving a block?

Changing Bitcoin For hard forks and soft forks each, answer the following with Always, Sometimes, or Never: The new rules are backwards compatible. The new rules are forwards compatible. Pool Strategies Quick review: what are the denitions of pay-per-share and proportional pool reward schemes? What are the advantages and disadvantages of each? Fill in the blank: A miner is incentivized to switch from ______ to ______when the expected price per share of the rst pool goes______ the price per share of the second. proportional, pay-per-share, above proportional, pay-per-share, below pay-per-share, proportional, above pay-per-share, proportional, below Forking and Double Spending 1.What is hard fork and what is soft fork? 2.What is a race attack? Describe how a race attack can be used to double spend on someone? 3.What is the denition of a conrmation? How do these deter double spend attacks? 4.What is required of an attacker to double spend on someone who waits for conrmations? 5.Is it possible to stop someone from double spending if they have 51 percent of the mining power? 6.Trivia: What is the average number of conrmations that people wait for in the real world? 7.What are some reasons to stop an attacker from launching a double spend attack? 8.What are some ways to launch an attack and make prot? Selsh Mining 1.What is selsh mining? 2.What is signicant about the word selsh in the context of blockchain? Hint: recall the whole purpose of incentive alignment. 3.How much mining power does an attacker need to always lose the race and still be protable? Open-Ended Questions 1.What are the tradeos between using centralized services, like traditional banks, and decentralized services, like cryptocurrencies? 2.Can Bitcoin be considered a currency? What are the similarities and dierences between Bitcoin and at money? 3.If you were to design a cryptocurrency like Bitcoin, what properties would you want it to have that Bitcoin doesnt? Why? 4.Can you think of any other scenarios in which decentralization of a currently centralized service may be useful? 5.Now you know everything about Bitcoin, from the theory to the motivations to the implementation to the real-world manifestation. How well do you think Bitcoin accomplishes its goal? (The goal itself is up to debate.) 6.Dierent parts of the world require dierent mining costs. Particular parts of a country might provide cheaper electricity due to surpluses not bought back by the government, colder temperatures may require less articial cooling. Does this make Proof-of-Work unfair?