Questions & explanations
1. Give an example of a real-world action blockchain developers are taking now to prepare for quantum computing risks.
Many blockchain projects are researching and implementing quantum-resistant signature schemes. For example, the Ethereum community is exploring the use of Lamport signatures or STARKs (Scalable Transparent Arguments of Knowledge) that are believed to be quantum-safe. Some blockchains, like Bitcoin, have discussed adding a soft fork to allow users to move funds to quantum-resistant addresses. Additionally, the National Institute of Standards and Technology (NIST) is standardizing post-quantum algorithms, and blockchain developers are monitoring these standards to adopt them. These proactive steps aim to ensure that blockchains can transition to quantum-safe cryptography before quantum computers become a threat.
2. How might a quantum computer threaten the security of a blockchain's consensus mechanism, such as proof of work?
Proof of work (PoW) requires miners to solve a cryptographic hash puzzle, which is designed to be hard for classical computers. A quantum computer could use Grover's algorithm to find the solution much faster, effectively reducing the difficulty and allowing a single miner to dominate the network. This would break the decentralization of mining and could lead to a 51% attack, where the attacker controls the majority of mining power and can reverse transactions. However, the speedup from Grover's algorithm is only quadratic, so a quantum computer would need to be very powerful to pose a practical threat. Blockchains can mitigate this by switching to quantum-resistant consensus mechanisms.
3. Explain how a quantum computer could break the cryptographic algorithm used to secure Bitcoin transactions.
Bitcoin uses a cryptographic algorithm called ECDSA (Elliptic Curve Digital Signature Algorithm) to create digital signatures that prove ownership of coins. A sufficiently powerful quantum computer could run Shor's algorithm, which can efficiently solve the mathematical problem that ECDSA relies on (the discrete logarithm problem). This would allow an attacker to derive a private key from a public key, enabling them to forge signatures and steal bitcoins. However, this requires a quantum computer with thousands of stable qubits, which does not exist yet. Researchers are working on quantum-resistant algorithms to replace ECDSA before quantum computers become a threat.
4. How does a secure element enable offline CBDC payments?
A secure element is a special tamper-proof chip that safely stores digital money and private keys. It is like a safe inside your phone. When you make an offline payment, the secure element checks that you have enough balance and then subtracts the amount from your stored value. It also receives the payment from the other device. Because the chip is isolated from the phone's operating system, it is hard for hackers to steal the money. The secure element ensures that the same digital money cannot be spent twice offline, because it updates the balance locally. Later, when the device connects to the internet, the secure element syncs with the central bank's system.
5. How does the debate over programmability differ from the debate over smart contracts?
The debate over programmability focuses on whether the CBDC itself should have built-in rules, like expiration dates or spending limits. The debate over smart contracts is about whether the CBDC platform should allow third-party developers to create custom programs that run on top of the CBDC. Some argue that smart contracts enable innovation, like automatic payments for rent or insurance. Others worry that smart contracts could introduce risks, such as bugs or malicious code. The key difference is: programmability is about the central bank setting rules, while smart contracts are about users creating their own rules. Both raise questions of control and safety.
6. During a stock market crash, what typically happens to cryptocurrency prices, and why?
During a stock market crash, cryptocurrency prices often also fall sharply. This happens because investors panic and sell risky assets, including crypto, to raise cash or reduce losses. Many institutional investors treat crypto as a high-risk asset similar to tech stocks, so they sell both during market stress. Additionally, when liquidity dries up, even safe-haven assets like gold can drop temporarily, and crypto, being more volatile, falls even more. However, in some cases, crypto may recover faster if it is seen as a hedge against traditional financial system problems. Overall, the correlation between crypto and stocks tends to increase during crises.
7. Explain how a company can issue tokenized shares on a blockchain instead of traditional stock certificates.
Tokenized shares are digital tokens on a blockchain that represent ownership in a company, similar to traditional shares but in digital form. The company creates a smart contract that issues a fixed number of tokens, each representing a fraction of the company's equity. These tokens can be sold to investors through a security token offering (STO). Ownership is recorded on the blockchain, making it transparent and easy to transfer. Tokenized shares can be traded on decentralized exchanges 24/7, and dividends can be automatically distributed via smart contracts. This reduces paperwork and allows for fractional ownership, making investment more accessible.
8. What is a post-quantum cryptographic algorithm, and why is it important for blockchain security?
A post-quantum cryptographic algorithm is a type of encryption or signature scheme that is believed to be secure against attacks from both classical and quantum computers. These algorithms are designed based on mathematical problems that are hard for quantum computers to solve, such as lattice-based, code-based, or hash-based problems. They are important for blockchain security because, if quantum computers become powerful enough, they could break current algorithms like RSA or ECDSA, which are widely used in blockchains. By adopting post-quantum algorithms, blockchains can remain secure in the future. Many projects are already testing these algorithms.
9. Compare the executive order's approach to digital assets with a country that has already launched a CBDC, like China.
The US executive order focused on studying and regulating digital assets carefully, without rushing to launch a CBDC. In contrast, China has already launched a digital yuan (e-CNY) and is testing it widely. China's approach is top-down, with the government pushing adoption, while the US order emphasizes research, consumer protection, and private-sector innovation. The US order also addresses risks like money laundering and financial stability, whereas China's main goal is to control the financial system and reduce reliance on private payment apps. So, the US is more cautious and collaborative, while China is more directive and advanced in CBDC rollout.
10. How can a central bank's monetary policy be affected if many people in the country start using a cryptocurrency instead of the national currency?
If many people switch to a cryptocurrency, the central bank loses control over the money supply because it cannot create or destroy that cryptocurrency. The demand for the national currency falls, which can weaken its value and make it harder for the central bank to manage inflation or stimulate the economy. Also, the central bank's interest rate changes may have less effect because people can borrow or lend in crypto outside the banking system. This reduces the effectiveness of monetary policy tools like setting interest rates or reserve requirements. Overall, widespread crypto adoption can undermine a central bank's ability to stabilize the economy.
11. Explain how stablecoins could still be useful even if a CBDC exists.
Even with a CBDC, stablecoins can serve purposes that CBDCs might not cover. For example, stablecoins can be used in decentralized finance (DeFi) platforms for lending, borrowing, or trading without a central authority. They can also facilitate cross-border payments faster and cheaper than traditional banks, especially in countries without a CBDC. Some people might prefer stablecoins for privacy, as CBDCs could allow the central bank to see all transactions. Additionally, stablecoins can be programmed with smart contracts to automate payments, which may not be a feature of the CBDC. So, stablecoins and CBDCs can coexist, each serving different needs.
12. Give an example of a risk that tokenized equity investors face that traditional stock investors do not, and explain why.
One risk is that the smart contract governing the tokenized shares could have a bug or be hacked, leading to loss of funds or ownership records being altered. Traditional stock investors rely on centralized systems like depositories and brokerages that have insurance and legal protections. In contrast, tokenized equity often lacks such safeguards, and if the blockchain platform fails, investors may have no recourse. Additionally, regulatory uncertainty means that tokenized shares might not be recognized as legal ownership in some jurisdictions, leaving investors without shareholder rights like voting or dividends. This makes tokenized equity riskier.