Week 12 Review Questions - Blockchain

What role does hashing play in blockchain security?

Ensures data integrity by producing a unique, irreversible value

What does a digital signature verify in a blockchain transaction?

The authenticity of the sender

How do hashing and digital signatures work together in blockchain transactions?

They ensure integrity and authenticity of transactions

What does a website actually store when you create a password?

A hashed version of your password

Why does storing hashed passwords protect users from hackers?

Hashes cannot be feasibly reversed to reveal the original password

The SHA-256 algorithm can produce how many unique combinations?

2^{256}

Approximately how many unique combinations exist in SHA-256?

1.157 \times 10^{77}

A 256-bit hash represents data as what?

Binary digits (1s and 0s)

A 64-character hexadecimal hash represents data as what?

Base 16 characters (0–9, a–f)

Why are hexadecimal hashes used instead of raw binary output?

They are human-readable and more compact

When a message is encrypted using public/private key encryption, what key does the sender use?

Receiver’s public key

In public/private key encryption, what key is required to decrypt the message?

Receiver’s private key

What main benefit does public/private key encryption provide?

Confidentiality

Why does blockchain’s linking of all transactions since inception add value?

It provides a full, verifiable history

How does blockchain enhance traceability in supply chains?

Each transaction links to prior records for transparency

What is a distributed ledger?

A shared, synchronized record across all blockchain participants

How does a distributed ledger improve security?

It requires hacking all copies simultaneously to alter data

What characteristic of a distributed ledger ensures transparency?

Replication of data among all nodes

What is a key characteristic of a Private (Permissioned) blockchain?

Participation limited to known trading partners

In a Private Blockchain, who can process transactions?

Selected or authorized nodes only

In a Private Blockchain, who can view transactions?

Only permitted participants

In a Public (Permissionless) blockchain, who can join the network?

Anyone, without restriction

What is a defining feature of a Public Blockchain?

Anonymity and visibility for all transactions

Why is anonymity important in a public blockchain?

It protects user identity and decentralization

How does blockchain ensure data integrity across the network?

By distributing identical copies of data to all participants