(SEM VI) THEORY EXAMINATION 2021-22 BLOCKCHAIN ARCHITECTURE DESIGN

BLOCKCHAIN ARCHITECTURE DESIGN (KIT061)

B.Tech Semester VI – Theory Examination (2021–22) 

Blockchain Architecture Design is a modern computing subject that focuses on the design principles, internal structure, cryptographic foundations, and consensus mechanisms of blockchain systems. Blockchain is a distributed, immutable, and decentralized ledger technology that enables secure and transparent recording of transactions without relying on a central authority. The subject integrates concepts from distributed systems, cryptography, networking, databases, and security, and its applications span cryptocurrencies, supply chain management, healthcare, identity management, and financial systems.
 

The uploaded question paper clearly shows that the examination emphasizes blockchain fundamentals, distributed ledger technology, cryptography, hashing, consensus protocols, permissioned and permissionless blockchains, Hyperledger Fabric architecture, Merkle trees, Proof of Work, KYC applications, and blockchain security threats. To score well, answers must be written in clear, logically connected paragraphs, with proper justification, conceptual depth, and correct technical terminology.
 

SECTION A – BASIC BLOCKCHAIN CONCEPTS

(Based on Section A on Page-1 of the paper) 

In a blockchain database, there are two types of records, namely transaction records and block records. Transaction records store individual transaction details, while block records store metadata such as block hash, previous block hash, timestamp, and Merkle root, thereby linking blocks together.

The key features of blockchain include decentralization, immutability, transparency, distributed consensus, and cryptographic security. These features collectively ensure that data stored on the blockchain cannot be altered maliciously and remains verifiable by all participants.
 

The role of encryption in blockchain is fundamental to ensuring data confidentiality, integrity, and authentication. Encryption techniques such as public-key cryptography protect transaction data and ensure that only authorized users can initiate transactions.
 

Once data is written into a block and the block is added to the blockchain, it is not practically possible to modify the data. Any change would alter the block hash, which would break the chain linkage and be immediately detected by the network.
 

The Double Spending problem refers to the risk that a digital asset may be spent more than once. Blockchain solves this problem by maintaining a single, shared ledger that verifies and confirms each transaction through consensus.
 

KYC (Know Your Customer) is a verification process used to identify and authenticate users. Blockchain improves KYC by enabling secure, tamper-proof, and reusable identity verification.
 

The characteristics of cryptography include confidentiality, integrity, authentication, and non-repudiation. These characteristics are essential for secure blockchain operations.
 

Blockchain is considered a trusted approach because trust is established through cryptographic proof, distributed verification, and consensus rather than reliance on a single central authority.
 

Despite its advantages, blockchain has limitations such as scalability issues, high energy consumption in some consensus mechanisms, latency, and regulatory challenges.
 

A 51% attack occurs when a single entity controls more than half of the network’s computational power, enabling it to manipulate transaction ordering or prevent confirmations, though such attacks are extremely costly in large networks.
 

SECTION B – DISTRIBUTED LEDGER, CONSENSUS & TOOLS

(Based on Section B on Page-1) 

Distributed Ledger Technology (DLT) refers to a system where multiple participants maintain synchronized copies of a ledger. Unlike an ordinary centralized ledger, a blockchain ledger is decentralized, immutable, and updated through consensus, eliminating single points of failure.

In permissioned blockchain networks, various consensus protocols are used, including Practical Byzantine Fault Tolerance (PBFT), Raft, and Proof of Authority. These protocols focus on performance, identity-based participation, and fault tolerance rather than open competition.

Blockchain offers significant benefits in the KYC process by reducing duplication of verification, enhancing security, lowering costs, and enabling faster onboarding while maintaining privacy and regulatory compliance.

Hyperledger Composer is a development tool used to model business networks. It provides components such as business network definition, assets, participants, transactions, and access control rules, simplifying blockchain application development.

The SHA-256 hashing algorithm is a cryptographic hash function that generates a fixed-length 256-bit hash. It is deterministic, collision-resistant, and irreversible, making it ideal for securing blockchain data and linking blocks.

SECTION C – TYPES OF BLOCKCHAIN & CORE STRUCTURES

(Based on Section C on Page-1) 

There are different types of blockchain, including public, private, consortium, and hybrid blockchains. Public blockchains are open and decentralized, while private blockchains restrict access and are controlled by organizations. Unlike traditional databases, blockchain ensures immutability, decentralization, and trustless operation.
 

Merkle trees are hierarchical data structures that enable efficient and secure verification of transaction integrity. Each leaf node represents a transaction hash, and parent nodes store hashes of their child nodes, culminating in a Merkle root stored in the block header.
 

PERMISSIONED BLOCKCHAIN & CONSENSUS MECHANISMS

(Based on Question 4 on Page-1) 

A permissioned blockchain restricts participation to authorized entities. Its design goals include identity management, data privacy, high throughput, and low latency. Consensus protocols such as PBFT and Raft are commonly used because they offer faster confirmation and lower resource consumption.
 

The Proof of Work (PoW) algorithm is a consensus mechanism where miners solve computational puzzles to validate blocks. While PoW provides strong security and decentralization, it suffers from high energy consumption and scalability limitations.
 

HYPERLEDGER FABRIC & TRANSACTION FLOW

(Based on Question 5 on Page-1) 

The Hyperledger Fabric architecture consists of peers, ordering service, channels, membership service provider, and chaincode. It supports modular consensus and private transactions, making it suitable for enterprise use.
 

The transaction flow in blockchain consensus involves proposal creation, endorsement, ordering, validation, and commitment. This process ensures consistency and agreement among network participants.
 

BLOCKCHAIN APPLICATIONS & SECURITY

(Based on Page-2 of the paper) 

Blockchain plays a crucial role in financial software and settlement systems by enabling faster, transparent, and secure transactions while reducing intermediaries.

Traditional supply chain systems suffer from lack of transparency, data tampering, and inefficiency. Blockchain overcomes these issues through decentralization, traceability, and real-time data sharing.

Key security principles in blockchain include cryptographic hashing, digital signatures, decentralization, consensus, and immutability, all of which help eliminate security threats.

Cryptographic digital signatures ensure transaction authenticity and non-repudiation by allowing participants to verify the sender’s identity and transaction integrity.

HOW TO WRITE BLOCKCHAIN ARCHITECTURE ANSWERS IN THE EXAM

In Blockchain Architecture Design, never write answers in short bullet points. Always begin with a clear definition, followed by explanation of working principles, architecture, algorithms, and applications. Use correct terminology such as distributed ledger, hashing, consensus, Merkle tree, PoW, and permissioned blockchain. Examiners give maximum weightage to conceptual clarity, logical explanation, and understanding of blockchain design principles.