Practical Outcome 1: Cryptography Foundations

Implement and test Diffie-Hellman key exchange, RSA key generation and encryption/decryption, and SHA-1 hashing. Focus on inputs, outputs, and security properties.

Practical Outcome 2: Blockchain Core Implementation

Build a Merkle tree, define a block structure, implement a basic blockchain, and simulate mining with adjustable difficulty. Extend this by creating an ERC20-style token model.

Practical Outcome 3: Case Study

Prepare a comparative case study on any two blockchain implementations (e.g., Bitcoin vs Hyperledger, or Ethereum vs Corda). Highlight consensus, identity model, privacy, and performance.

Blockchain is a distributed ledger where transactions are grouped into blocks that are chained using cryptographic hashes. Each participant keeps a replicated copy, which provides transparency and tamper evidence.

Key Concepts

Public and private keys enable asymmetric encryption, hashing ensures data integrity, and digital signatures provide authenticity and non-repudiation.

CAP states that in the presence of network partition, a distributed system must choose between consistency and availability. Public blockchains typically prioritize availability and partition tolerance, accepting eventual consistency.

Sidechains are separate blockchains that are interoperable with a main chain. Assets can be moved between chains using a peg mechanism, enabling experimentation or scalability without changing the main chain.

Identity in blockchain is based on public/private key pairs. The public key (or derived address) identifies the user, while the private key authorizes actions.

In a decentralized network, multiple nodes store the ledger and validate updates. No single node has exclusive control, improving resilience and trust.

Finality describes when a transaction is considered irreversible. PoW blockchains have probabilistic finality, while many PoS and BFT systems offer deterministic finality.

Block rewards incentivize miners to secure the network. Difficulty adjusts based on network power to keep block intervals stable.

Sybil attacks create many fake identities to influence consensus. A 51% attack occurs when a single entity controls the majority of consensus power, enabling double-spending or censorship.

Bitcoin uses Merkle trees to efficiently summarize and verify transactions. A Merkle root is stored in each block header and allows inclusion proofs with minimal data.

Bitcoin provides eventual consistency. BFT concepts explain how distributed systems tolerate faulty nodes while still reaching agreement.

Secure hashing links blocks and prevents tampering. Blocksize impacts throughput and decentralization. Mining is the competitive process of finding a valid block hash.

PoW uses computational puzzles to secure the ledger. Bitcoin Script is a simple, stack-based language for specifying spending conditions.

Smart contracts are programs deployed on the blockchain that execute automatically when conditions are met. They eliminate intermediaries and enable transparent automation.

DAOs are organizations governed by smart contracts and community voting. Rules are encoded in code and decisions are executed transparently.

DApps are applications that use blockchain for data, logic, or identity. Typically composed of a front end, smart contracts, and decentralized storage or backend services.