Скачать или смотреть Blockchain Technology Part 2 - Hashing, Public Key Encryption

Hi, I’m Sy “The IT Guy” Williams, the owner of TeamLogic IT of Orlando

In the previous video I provided an overview of Blockchain.

In this video I’m going to discuss

How Blockchains Work

The Role of Miners

Blockchain Immutability

A blockchain is a peer-to-peer network that consist of wallets and nodes.
A wallet can be a mobile or web based application. It has an address that can be the source and destination of a transaction.
Wallets are used to create transactions, cryptographically sign the transactions, and communicate the transaction to the nearest node.

All full nodes (called miners) receive all transactions either from a wallet or from a peer. Each node node will validate the transaction and bundle it with other transactions to create a block of transactions.
Each new block is connected to the previous block by placing the hash value of the previous block into the new block. The logging of the previous block hash value is what creates the chain. A hash is a fixed length cryptographic representation of the data.
When the node finds a specific hash value for the block it is creating it will add that block to its local copy of the blockchain.
The node will notify peers that it has successfully created a new block. All peers will validate the new block before accepting it/adding it to its local copy of the blockchain.

A hash is an algorithm that takes data input of any lengths and derives a unique fixed length output.
A hash can be thought of as a fingerprint of the data. The creation of the hash is a one-way process meaning you can convert data to a hash but you can not take the hash value and convert it back to the data.
The National Institute of Science and Technology (NIST) has published secure hash algorithms (SHA). Bitcoin uses secure hash algorithm SHA-256 and Ethereum uses secure hash algorithm SHA-3.
The one-way translation provides a mechanism to validate data without revealing it.

Public-key encryption uses two mathematically related keys:
a public key known to everyone and
a private key known only to the recipient of a message
Your public key is used to encrypt the message and can be shared
Your private key is used to decrypt messages, sign transactions, and should remain private. All transactions are digitally signed using private keys.

All blocks are linked to the previous block via the previous block hash

Any change to a block will change the block’s hash and invalidate succeeding blocks

Invalid blocks won’t be accepted by other nodes in the blockchain network

The other nodes will not add this change to their local copy of the blockchain