Blockchain – CISAT


Let's learn more about block-chain.

What is blockchain?

Blockchain is a distributed, decentralized, public ledger.

How does blockchain work?

Blockchain – The revolutionary technology influencing different industries magnificently was introduced in the business sectors with its first current application Bitcoin. Bitcoin is just a kind of digital currency (cryptocurrency) which can be used for trading in the place of fiat money. And the basic technology behind the success of cryptocurrencies is named as Blockchain.

A blockchain, initially block chain, is a growing list of records, referred to as blocks, which are connected using cryptography. Blockchain is resistant to modification of the information. The blockchain is an undoubtedly brilliant invention and it was invented by Satoshi Nakamoto in 2008. By enabling computerized data to be distributed however not duplicated, blockchain technology created the establishment of another kind of Internet.

How blockchain works.

A digital ledger that keeps the record of all transactions taking place on a peer to peer network

All information are transferred via
blockchain is encrypted, and
every occurrence recorded, meaning
it cannot be altered.

It can be used for much more than
a transfer of currency; contracts,
records or data that can be shared.

Encrypted information can be shared across
multiple providers with no risks of any
privacy breach.

It is decentralized, so there is no need for a central certifying authority for the possible

Blockchain can offer a leap to bridge the gaps existent in the current system, like a structure of Government Administration, Banking & Financial, Engineering, Businesses etc. Current technology has many ambiguities and flaws such as loss and theft of personal information. Blockchain has been identified as a potential solution for such challenges. It has all the features which can prevent the problems mentioned above. Moreover, the traceability feature makes it easy for anyone in the system to track the source of information in some time, which is not possible with the current technology, thus, making blockchain a huge success and basic support for the future course of action. In the age of cryptocurrencies, we hear about the underlying technology known as blockchain. At the center of blockchain technology is a publicly shared “Immutable Digital Ledger” – implies that it is basically a sealed record-keeping innovation.


Ledgers have been a part of how people exchange since about the start of our species and keeps on being the means by which we record transactions. Until blockchain, records were typically controlled by one entity and could be controlled without others knowing. US old-timers conjointly remember the long, blunder ridden manual record-keeping on inexperienced writing paper for sales transactions or inventory following — that is the reason VisiCalc, the essential electronic program, was such a distinct advantage. With just a single copy of any record, it's anything but difficult to control the information when "nobody is watching." Today's private records — regardless of whether it's in managing an account, property, expenses or medicinal services — expect us to "trust" the association that controls it. This middleman model is additionally in what capacity numerous worldwide associations have turned out to be so amazing; we're required to utilize them so as to execute a transaction. This system of secretly controlled records that don't converse with one another is additionally why such huge numbers of transactions take such a long time to execute.

What blockchain is not?

How Blockchain Works?

So, how does the blockchain work? Let's review a couple of key highlights before we dive into the details: As every transaction happens, it is put into a block Every transactions are blocked together after verification Every block is connected to the block before and after it Every block is added to the following in an irreversible chain 1. Blockchain tracks all data exchanges — this record is known to as a “ledger” in the cryptocurrency world, and each data exchange is a “transaction“. Every checked and verified transaction is added to the ledger as a “block”. 2. It uses a distributed system to check and verify every transaction — a peer-to-peer network of nodes. 3. When marked and confirmed, the new transaction is added to the blockchain and can't be changed. A blockchain is essentially a chain of blocks that contain data. Every block has its own hash and also the hash of the previous block.


A unit of data stored inside a block might be addressed by any value based on the type of the blockchain. A block can store an amount of money, a share in a company, a vote during an election, or any other value. A block stores encoded details about the parties whose interaction took place as a data stored in the block. A cryptocurrency block furthermore contains the sender’s and receiver’s encoded identifiers. For example, a block for an e-commerce transaction will carry the identifiers of the seller and buyer. Each block also has a hash. This hash is a value generated from a line of text utilizing a mathematical function. A hash can be collated to a fingerprint, as each hash is unique. Its role is to identify a block and the block’s content. Once a block is generated, a hash is calculated. Changing something inside the block makes the hash change. So a hash also shows changes made to the block. If anyone changes the data in a single block, the hash of that specific block changes, yet it also makes the entire chain invalid.


A hash is an extraordinary tool for detecting attempts to change data in blocks. However, a hash algorithm alone isn't sufficient to establish the security of a blockchain. To reduce attempts to corrupt the blockchain and to guarantee security, blockchain technology also uses a process called proof-of-work.


Proof-of-work is a process of generating data that are difficult to get, however, easy to verify. With regards to a blockchain, proof-of-work is about solving mathematical problems. If a problem is successfully resolved, then a new block can be added to the blockchain. On average, performing proof-of-work calculations and adding another block to the chain takes around 10 minutes.

What’s behind the proof-of-work process?

Computers that establish the blockchain network race to solve a mathematical problem to get a reward and be the first to add the next block to the chain. Mathematical problems in blockchain must be difficult to solve but easy to check in order to prevent cheating. Together, hashing and the proof-of-work technique ensure the security to the entire blockchain network. Longest Chain Since a blockchain contains a vast number of nodes, each of them is simultaneously carrying out proof-of-work. Thus, a situation when various nodes cope to complete proof-of-work with a valid result is pretty common. When this happens it’s known as a hard fork, which describes exactly what happens to the blockchain – it forks. When new blocks are generated and added to one of these forked chains, it turns into the longest and again the only valid chain. Blockchain nodes reject the blocks from other forked chains, and all the transactions held in those blocks are sent for verification again. So far, the longest fork made it is no more than five blocks in a row.

Digital Wallet

Along with hashing and proof-of-work, a blockchain wallet likewise works to ensure the safety of transactions and prevent fraud. A wallet creates paired public and private keys that further ensure the security of transactions as well. A public key can be contrasted with a postbox. Anybody can put a letter inside of it, however, they can’t get that letter back. Only a postal authority who has a private key can open the postbox and get the letter. This is like how keys inside a blockchain work. Anybody can send a transaction using a public key to the address of a receiver. This is like putting a letter in a postbox. However, only the owner of that address who also has the private key can access the value of that transaction.

Distributed Network

Anybody is permitted to join a blockchain distributed network. When somebody joins a network, this individual gets a full copy of the blockchain. Distributed storage of data along with the effective hashing and proof-of-work techniques helps to prevent almost any fraud.

Important points:

A Blockchain is a kind of diary or spreadsheet containing information about transactions. Each transaction produces a hash. A hash is a series of letters and numbers. Transactions are entered in the order in which they happened. The order is critical. The hash relies on the transaction as well as the previous transaction's hash. Even a little change in a transaction creates a totally new hash. The nodes check to ensure a transaction has not been changed by analyzing the hash. If a transaction is accepted by a large number of nodes then it is written into a block. Each block refers to the previous block and in collaboration make the Blockchain. A Blockchain is strong as it is spread across many computers, all of which has a copy of the Blockchain. Those computers are called as nodes. The Blockchain upgrades itself every 10 minutes.

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Source Videos for Creating Blockchain

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