Mixed Deck — All CBCP Topics Flashcards

Which of the following best describes the principle of decentralization in blockchain technology?

Answer: Control and decision-making are distributed across a peer-to-peer network of participants.

Decentralization is a core concept of blockchain, meaning there is no central authority. Instead, control and data are distributed among the network's participants (nodes), who collectively validate transactions and maintain the ledger. This removes single points of failure and makes the network resistant to censorship and manipulation.

What is a Pedersen commitment, and where is it commonly used in blockchain privacy?

Answer: A homomorphic commitment scheme allowing arithmetic on hidden values, used in confidential transactions

Pedersen commitments are computationally hiding and perfectly binding; their homomorphic property allows verifying transaction balance without revealing amounts, as in Confidential Transactions.

In a Proof of Authority (PoA) consensus mechanism, how are block validators chosen?

Answer: They are pre-approved, known entities whose identities and reputations are at stake.

In a Proof of Authority (PoA) network, validators are not anonymous. They are a limited set of pre-approved participants who are chosen based on their real-world identity and reputation. Instead of staking computational power (PoW) or capital (PoS), they stake their reputation. This model is common in private or consortium blockchains where trust and performance are prioritized over decentralization.

Which consensus mechanism is most suitable for a consortium blockchain where all participants are known and semi-trusted?

Answer: Practical Byzantine Fault Tolerance (PBFT)

PBFT is well-suited for consortium blockchains with a known, limited set of semi-trusted validators due to its deterministic finality and low energy consumption.

In Solidity, what is the difference between 'storage' and 'memory' variable locations?

Answer: Storage is permanent and persists on-chain; memory is temporary and exists only during execution

Storage variables are written to the blockchain and persist between transactions, while memory variables are temporary and discarded after function execution ends.

What consensus algorithm is this?

Answer: Proof of Stake (PoS)

Proof of Stake (PoS) is a consensus algorithm where validators are chosen to create new blocks based on the amount of cryptocurrency they 'stake' as collateral. Instead of expending computational power like in Proof of Work, PoS incentivizes honest behavior by requiring participants to lock up their assets. This mechanism secures the network by making it economically unfeasible for malicious actors to attack the chain, as they would risk losing their staked funds.

What role does a lightweight node play in a blockchain network?

Answer: It verifies transactions by piggybacking on the work of full nodes.

A lightweight node, also known as a Simple Payment Verification (SPV) client, does not store the entire blockchain history. Instead, it relies on full nodes to provide proof of transactions by downloading only block headers and Merkle proofs. This allows lightweight nodes to verify the validity of transactions with minimal storage and computational resources, making them suitable for mobile devices or users who don't need to run a full node.

What benefits may blockchain networks bring to the Internet of Things (IoT)?

Answer: Avoiding a spoofing attack using the secured identity that is stored on a blockchain

Blockchain networks can significantly enhance the security of IoT devices by providing a secure and immutable ledger for device identities. By storing verified identities on a blockchain, it becomes much harder for malicious actors to impersonate legitimate devices, thereby preventing spoofing attacks. This ensures that only authenticated IoT devices can participate and interact within the network, building a more trustworthy ecosystem.

What is 'flash loan' in DeFi smart contracts?

Answer: An uncollateralized loan that must be borrowed and repaid within a single transaction

Flash loans are atomic, uncollateralized loans where borrowing and repayment occur in one transaction; if repayment fails, the entire transaction reverts.

Which component of asymmetric cryptography is used to verify a blockchain transaction's digital signature?

Answer: The sender's public key

Anyone can use the sender's public key to verify that the signature was created by the corresponding private key, confirming authenticity without exposing the private key.

Compared to the RSA algorithm, what is the primary advantage of using Elliptic Curve Cryptography (ECC) for generating key pairs in blockchain systems like Bitcoin and Ethereum?

Answer: It provides the same level of security with significantly smaller key sizes.

The main advantage of ECC over RSA is its efficiency. ECC can provide the same level of cryptographic security as RSA but with much smaller key sizes. For example, a 256-bit ECC key offers comparable security to a 3072-bit RSA key, which leads to lower computational overhead and faster processing, crucial for blockchain performance.

What is the 'ABI' (Application Binary Interface) in the context of Ethereum smart contracts?

Answer: A JSON description of a contract's functions and events used to encode/decode interactions

The ABI is a JSON specification that defines how to encode function calls and decode return values when interacting with a deployed smart contract.

In the context of blockchain, what is a smart contract?

Answer: A self-executing program stored on the blockchain that automatically runs when predetermined conditions are met.

A smart contract is essentially a piece of code that lives on the blockchain. It is programmed to execute specific actions automatically based on 'if-then' logic once its predefined conditions have been fulfilled, removing the need for intermediaries.

What is a 'governance token' in the context of decentralized protocols?

Answer: A token that grants holders voting rights over protocol changes and treasury decisions

Governance tokens give holders the ability to propose and vote on protocol upgrades, parameter changes, and treasury allocations in a decentralized autonomous organization.

In a Delegated Proof of Stake (DPoS) system, what role do 'witnesses' or 'delegates' play?

Answer: They are elected nodes responsible for producing blocks on behalf of token holders

In DPoS, token holders vote to elect a fixed set of delegates/witnesses who produce blocks and validate transactions on behalf of the network.

In Hyperledger Fabric's transaction lifecycle, what is the specific role of an 'endorsing peer'?

Answer: To execute a chaincode transaction proposal, sign the result, and return it to the client.

The endorsing peer's primary role is to receive a transaction proposal from a client application, simulate the transaction by executing the specified chaincode, and then sign the read-write set (the results). This signed proposal response, or 'endorsement', is sent back to the client. It does not commit the transaction to the ledger at this stage. [8, 21]

What is an 'Initial DEX Offering' (IDO)?

Answer: A fundraising method where new tokens are sold and listed directly on a decentralized exchange

An IDO is a token launch on a DEX launchpad, providing immediate liquidity and trading without the gatekeeping of centralized exchanges.

In a Merkle Patricia Trie used by Ethereum, what node type stores a single key-value pair with a non-shared path?

Answer: Leaf node

Leaf nodes encode the remaining path and the terminal value, representing the end of a unique trie path.

A smart contract is designed to release payments to a supplier only after a shipment's arrival is confirmed by an IoT sensor. The blockchain network itself cannot directly access data from the IoT sensor. Which of the following is required to securely and reliably feed the external data to the smart contract?

Answer: A blockchain oracle

Blockchains are deterministic, isolated networks and cannot natively access external, off-chain data. A blockchain oracle is a service that connects smart contracts with off-chain data sources, acting as a bridge to provide the necessary external information in a trusted manner.

In Hyperledger Besu, what does 'IBFT 2.0' refer to?

Answer: Istanbul Byzantine Fault Tolerant consensus, version 2.0

IBFT 2.0 (Istanbul Byzantine Fault Tolerant) is a consensus algorithm in Hyperledger Besu designed for private Ethereum networks, offering immediate transaction finality.