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  Unit 3: Hash Functions, Cryptography, and Digital Signatures in Blockchain 1. Hash Function in Blockchain A hash function is a cryptographic algorithm that converts any input data into a fixed-size, unique string of characters (a hash value ). In blockchain, hash functions are crucial for: ·          Immutability: Each block includes the hash of the previous block, creating an unbreakable chain. Any alteration to an old block's data changes its hash, invalidating the subsequent block and making tampering easily detectable. ·          Data Integrity: Hashes act as a "digital fingerprint." If the hash of data matches a known hash, the data is confirmed to be unaltered. ·          Mining (Proof of Work): Miners in PoW blockchains compute hashes to find a specific output, securing the network and adding new blocks. ·     ...

  Unit 2: Foundations of Ownership, Security Related Concepts in Blockchain Foundations of Ownership In traditional systems, ownership is often documented and verified by centralized authorities (e.g., land registries, banks). In blockchain, ownership is established and proven through cryptographic methods, primarily using public-key cryptography . Public and Private Keys: Each user on a blockchain network has a unique pair of cryptographic keys: a public key and a private key. The public key acts as an address, similar to an account number, visible to everyone. It's used to receive assets or data. The private key is a secret code that grants control over the assets associated with the public key. Only the person possessing the private key can authorize transactions from that address. Digital Signatures: To prove ownership or authorize a transaction, a user digitally "signs" a message or transa...