Free Blockchain Developer Blockchain Fundamentals and Cryptography Questions and Answers 1 — Questions and Answers
Question 1: In public-key cryptography, which key is used to create a digital signature, and which key is used to verify it?
- The sender's public key creates the signature, and the sender's private key verifies it.
- The receiver's private key creates the signature, and the receiver's public key verifies it.
- The sender's private key creates the signature, and the sender's public key verifies it. (Correct answer)
- A shared secret key is used for both creation and verification.
Correct answer: The sender's private key creates the signature, and the sender's public key verifies it.
A digital signature is created using the sender's private key to prove their identity. Anyone can then use the sender's corresponding public key to verify that the signature is authentic and that the message hasn't been tampered with.
Question 2: A development team is building a decentralized application (dApp) that requires low transaction fees, high throughput, and the ability to handle complex computations. The consensus mechanism should also be energy-efficient. Which consensus algorithm would be the most suitable choice?
- Proof of Work (PoW)
- Proof of Stake (PoS) (Correct answer)
- Proof of Authority (PoA)
- Proof of Burn (PoB)
Correct answer: Proof of Stake (PoS)
Proof of Stake (PoS) is an energy-efficient consensus mechanism compared to Proof of Work (PoW). It generally offers higher throughput and lower transaction fees, making it suitable for dApps with complex computations and a need for scalability. PoA is less decentralized, and PoB is a less common alternative.
Question 3: Which of the following BEST describes the concept of 'immutability' in the context of a blockchain?
- Once a block is added to the chain, it can only be altered by a majority of network participants.
- Transactions are encrypted and cannot be read by unauthorized parties.
- Once a transaction is recorded in a block and added to the chain, it is computationally infeasible to alter or delete it. (Correct answer)
- The blockchain is stored on a single, secure server to prevent data loss.
Correct answer: Once a transaction is recorded in a block and added to the chain, it is computationally infeasible to alter or delete it.
Immutability is a core principle of blockchain technology. Due to the cryptographic hashing that links each block to the previous one, changing data in an older block would require re-mining that block and all subsequent blocks, which is considered computationally infeasible on a decentralized network.
Question 4: What is the primary function of a hashing algorithm, such as SHA-256, within a blockchain?
- To encrypt transaction data so that only the recipient can read it.
- To generate a unique, fixed-size output (a hash) from a variable-size input, ensuring data integrity. (Correct answer)
- To digitally sign transactions on behalf of the user.
- To determine the order of transactions within a block.
Correct answer: To generate a unique, fixed-size output (a hash) from a variable-size input, ensuring data integrity.
A hashing algorithm like SHA-256 takes any input data and produces a unique, fixed-length string of characters. In a blockchain, this is used to create a unique identifier for each block (by hashing the block's header) and to ensure the integrity of the data; any change to the input data results in a completely different hash.
Question 5: A consortium of shipping companies wants to create a shared, permissioned ledger to track cargo movements. They require a system where only pre-approved participants can join the network and validate transactions. Which type of blockchain architecture would be most appropriate for this scenario?
- Public Blockchain
- Private Blockchain
- Hybrid Blockchain
- Consortium Blockchain (Correct answer)
Correct answer: Consortium Blockchain
A consortium blockchain is governed by a group of organizations rather than a single entity. It is permissioned, meaning only authorized nodes can participate. This model is ideal for collaboration between different firms in the same industry, like the shipping consortium described.
Question 6: What is a Merkle Tree, and what is its primary benefit in a blockchain?
- A data structure that organizes user accounts, making wallet lookups more efficient.
- A governance model for voting on protocol upgrades.
- A tree structure of cryptographic hashes of transactions that allows for efficient and secure verification of transaction content. (Correct answer)
- A type of consensus algorithm that relies on a hierarchy of nodes.
Correct answer: A tree structure of cryptographic hashes of transactions that allows for efficient and secure verification of transaction content.
A Merkle Tree is a data structure where each leaf node is a hash of a transaction, and each non-leaf node is a hash of its child nodes. The Merkle root, the single hash at the top of the tree, is included in the block header. This allows for 'Simplified Payment Verification' (SPV), where a node can verify if a transaction is included in a block by downloading only the block header and the relevant branch of the tree, not the entire block.
Free Blockchain Developer Blockchain Fundamentals and Cryptography Questions and Answers 1
In public-key cryptography, which key is used to create a digital signature, and which key is used to verify it?