How to Create a Blockchain

How To Create Blockchain In JavaScript

By Krunal Last updated Dec 14, 2018

In this tutorial, we will see . Blockchain keeps the record of all data exchanges — this record is referred to as the » ledger» in the cryptocurrency world, and each data exchange is the » transaction.» Every verified transaction is added to the ledger as a » block.» It utilizes the distributed system to verify each transaction — the peer-to-peer network of nodes. Once signed and verified, a new transaction is added to the blockchain and cannot be altered.

The blockchain is a structure of data that represents the financial ledger entry, or a record of a transaction. Each transaction is digitally signed to ensure its authenticity and that no one tampers with it, so a ledger itself and the existing transactions within it are assumed to be of high integrity.

In this tutorial, we will create the simple blockchain in javascript in which we use Javascript as a language and Node.js as a backend to run the small project.

Now if we need to create a simple Blockchain in Node.js, then we need to have one Genesis Block

You can refer to Genesis Block as the first block of Blockchain because Blockchain is an array of blocks and Genesis is the first block of the Blockchain.

Genesis Block

The is the first block of the blockchain. The genesis block is generally hardcoded in the applications that utilize its blockchain. The Genesis Block is also known as Block Zero or Block 0. It is an ancestor that every Blockchain network’s block that can be traced to its origin back. Remember how every block in the Blockchain is linked back to the previous block using the hash in the block header? You keep going back, and you realize every block is hence connected to the genesis block.

Our Genesis Block contains the following fields or properties.

1. timestamp
2. lastHash
3. hash
4. data

So, if we combine all these properties into one object, then it will become a Genesis Block. So based on this block, we will mine the second block. Then from the second block, we will extract the third block and so on. That is why we need a Genesis Block to start a Blockchain.

Now, let us start a project by creating a project folder and then start building awesome blockchain using Javascript.

Step 1: Create a project and create a Genesis Data

Go inside that folder.

Now, generate the package.json file in the case in future, we need to install any node modules.

Remember, I am using Node v11.3.0.

Next step is to create a new file inside the root called genesis.js and add the following code.

Here, we have taken an object with its initial values.
As I have defined earlier, our block contains the four properties. This is a genesis data, so we need to hardcode this values.

The properties timestamp and data are you can understand. But I have used SHA256 algorithm to convert the simple text into hash text.

Actual text for lastHash is a krunal, and actual text for the hash is a krunalHash.

Here, you can enter my name as a text, and it will give the SHA256 hash of that text. Now, you need to convert that text to lowercase by using Javascript’s toLowercase(). That is it. You will find the exact hash like me. Cool!! So now, you have Genesis Data is ready. The next thing is to create a Block from this data.

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Step 2: Create a Block

Inside your project root, create a file called block.js and add the following code.

So, here we have imported the GENESIS_DATA for our block.

Then we have defined the Block class and passed the parameters to the constructor when we create an object of the Block.

We have also defined the static method called genesis() which is responsible for returning the Genesis Block for our blockchain.

Remember, we have previously defined the GENESIS_DATA not block. After creating an object of this class, it will become a Genesis Block.

Step 3: Create a hash based on a previous block.

We need to define a function that can create a hash based on the previous block’s hash.

So, first let us create a new file inside the root called crypto-hash.js and add the following code inside it.

Now, to create a Hash, we need the three properties.

1. timestamp
2. lastHash
3. data

So, we have first required the crypto module provided by the Node.js.

Then we have defined the function called cryptoHash() which will accept the inputs. Here we have used spread operator which is the syntax of ES6.

Inside that function, we have called the createHash() method and pass the sha256 as a parameter. That means we need to create a hash based on the sha256 algorithm.

Then we have sorted and join that three parameters and return its hex values.
So, finally, we can get the current block’s hash based on the previous block’s three properties.

Step 4: Mine a new Block based on a previous Block

So, we got the Genesis Block and the hash of that block. Now, we need to write the function that can generate a new Block based on the previous block. Right now, in our case, it is a Genesis Block.

Now, import the crypto-hash module inside the block.js file and create a new function called mineBlock() and pass the two parameters.

1. lastBlock
2. data

So, our final block.js file looks like this.

So, here we have defined the method called mineBlock and pass the two parameters. The mineBlock() will return a complete new Block based on the previous block.

Now, it is the time to create a Blockchain from these blocks.

Step 5: Create a Blockchain

We have completed the step of creating a Genesis Block and mining a new Block. Now it is the time to develop a blockchain. That is why create a new file inside the root called blockchain.js and add the following code inside it.

So, first, we have imported the Block.js file and then create a class called Blockchain.

The Blockchain class is responsible for adding a new block inside the blockchain.
The blockchain is an array of the blocks starts with Genesis block.

So in the constructor, we have not defined an empty array. Instead, we have filled the chain array with the Genesis block.

Then we have defined one function called addBlock() which accepts the data.

Now, before adding a new block to the chain array, we need to mine it. That is why we have called the Block class’s mineBlock() method to extract a new block.

For mining a new block, we need a previous block and data. That is why we have used this code this.chain[this.chain.length-1] because it will return the last block in the blockchain and data is already we are passing to that function. So we get the new block based on the previous block and data.

Next step is to add that newly mined block inside our blockchain, and that is it.
The last step is to run this project and get the blockchain.

Step 6: Run the project and get the blockchain.

Now, the last step is to create a file inside the root of the project called server.js and add the following code.

So, here we have imported both the block.js and blockchain.js file and created an object of the Blockchain.

Then we will loop through that blockchain and add the data to that blockchain and created the six blocks in the blockchain because one is Genesis and five based on previous blocks.

Go to the terminal and start the node server.
You will see an output like this.

Finally, How To Create Blockchain In JavaScript Tutorial With Example is over. Now you have a clear understanding of Blockchain technology and how we can start coding in it. Above example is an elementary example of implementing a blockchain. Real-world examples are very complicated but this is the first step to enter the blockchain world and become a blockchain developer.

Important: Blockchain is being applied to various products from different industries; we just need more daring entrepreneurs who are willing to put a lot at stake.

Note: This article does not explain the blockchain concepts; instead, it focuses on developing a fintech application using this technology. I will explain why fintech can already adopt the blockchain, and most importantly, focus on developing a decentralized application using this technology.

How to build your own blockchain for a financial product

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Table of Contents

Important: Blockchain is being applied to various products from different industries; we just need more daring entrepreneurs who are willing to put a lot at stake. Industries That Are Ready For Blockchain

The Ultimate Guide On What You Need To Consider Before Building a Fintech Product

I will explain why fintech can already adopt the blockchain, and most importantly, focus on developing a decentralized application using this technology.

Fintech deals with a very thorny matter – money. It is exactly where most fraud takes place. The desire to become richer is one fundamental mechanism that pushes people to do things, often bad things. Fintech startups aim to improve the traditional financial institutions, for example, excluding the human factor from the financial activities.

Для регулирования сложности алгоритма, мы можем модифицировать количество лидирующих нулей. Одна четырех будет достаточно. Вы можете попробовать сами и понять, что добавление одного единственного лидирующего нуля приведет к гигантской разнице во времени поиска решения.

Пишем свой блокчейн

Предположим, что хэш некоторого целочисленного числа x, умноженного на другое целочисленное число y, должен заканчиваться на 0.

Настраиваем Flask для того, чтобы реализовать свой блокчейн

Итак, нам понадобится способ добавления транзакций в блок. Наш метод new_transaction() отвечает за это, и он довольно простой: Endpoint для майнинга

Каждый блок содержит в себе индекс, временную метку (timestamp, по Unix времени), список транзакций, доказательность (proof, подробнее об этом позже) и хэш предыдущего Блока.

Итак, нам понадобится способ добавления транзакций в блок.

Но понять, как работают Блокчейны не так просто – ну или, как минимум для меня, это сложно. Я с трудом пробирался сквозь множество непонятных видеороликов, сомнительных туториалов и боролся с сильным разочарованием от очень малого количества примеров. Поэтому мы с вами на.

To create a blockchain will require powerful equipment. When a new unit is formed, information is included in the general system by passing through preliminary encryption using the cryptography method.

How to create a blockchain

To create a blockchain will require powerful equipment.

Stages of creation

In conclusion, we note: if you decide to grow a chain, you will need a significant complication of the program with the addition of a server level. It will allow you to track changes in chains on many automated systems and limit the addition of blocks in a certain time period. Security and Protection

The string contains data lines that pass through premature cryptography using encryption. In addition to the new block, encryption and past arrays are required.

This is a public database, where new information and algorithms are recorded in the form of special blocks.

The system built on the blockchain is considered one of the most reliable. Cryptocurrency can not be faked or stolen. This is due to the fact that:

How to Create Your Own Cryptocurrency Blockchain in Python

Tutorial: Create a blockchain application for Azure Blockchain Workbench

§ Add the constructor function to your contract in your HelloBlockchain.sol smart contract code file.
As a best practice, indicate the version of Solidity you are targeting. Specifying the version helps avoid incompatibilities with future Solidity versions.