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My Dear Friends
This is @ns-porosh from Bangladesh 🇧🇩

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Introduction

How are you all? I hope you are well by the grace of God.I am well with your prayers and mercy God's grace.At first of all thank you to the sir @stream4u. Your lesson provides a lot of information on homework tasks.

1:-What is Blockchain and What are the types of Blockchains / Explain in detail the types of Blockchain?

What is Blockchain?

Blockchain is basically a combination of two different words, block and chain. It was first used in 2008. The use of blockchain technology was originally invented to trade cryptocurrencies. Blocks in blockchain technology contain data. Blockchain basically builds huge databases. Once data is recorded in a block as opposed to a centralized database in a blockchain, it is impossible for a third party to change it. Simply put we see a large ledger of almost all offices where basically different information is recorded. This information cannot be viewed or accessed by any third party other than the office worker. Transactions that take place when trading cryptocurrency i.e. bitcoin are stored in a chain system using blockchain. In this system, all transactions between users are verified and saved by a network with the help of verification and analysis.

When a person wants to sell or send bitcoin to another person through blockchain, that is, when a person sends bitcoin to another person's address, the transaction will be made in a block. Each block has a pre-specified address. The blocks are incorporated into the system within a specific rule structure by forming a chain by joining them together. This process is called process in the block registry.When creating a new block the properties of the previous block are taken into account and the blocks are included in a chain. However, many computers work to make all blockchain transactions in one block, and all computers have a copy of that block. Basically a blockchain is a reliable block where a database of suspicious transactions is created. The blocks that make up these databases.

What are the types of Blockchains?

There are generally four main types of blockchain networks. The blockchains are:

• 1:-Private Blockchains
• 2:-Public Blockchains
• 3:-Hybrid Blockchains
• 4:-Consortium Blockchains

Private Blockchains

This blockchain is basically a small blockchain that works in a limited environment. The Private Blockchains is the permission network. When someone wants to join the network or enter the network, he has to get the approval of the administrator. However, there is a limitation between the various participants and verifiers of this network. Because it controls third parties. It's like a centralized network. Blockchain allows participants to join the network, providing security, transparency and trust. However, in case of permission, there is approval of a third party. Third parties are also responsible for other settings of the network. Without the permission of the blockchain owner No one in this blockchain can read or write data. In other words, this blockchain works in a limited space.

Advantages

• This type of network has only a few participants which makes transactions very fast.

• Private blockchain prevents third parties from accessing various information on the network. Only a few nodes are required to verify transactions on a blockchain network, and it is determined by the network organization to add or change nodes to this blockchain network.

Disadvantages

• The private blockchain is much more centralized. This blockchain technology requires approval to manage transactions

• Once a node is created in a private blockchain, everything is lost later, so it can be said that there is some security risk in a private blockchain.

Public blockchain

Basically this blockchain is the first type of blockchain technology.This blockchain technology is unauthorized. This means that in this blockchain technology there is no restriction between participants and validators for a user to join and perform transactions. This blockchain technology helps reduce the risks that come with centralization such as low security and transparency. Even with this blockchain technology internet connection anyone can access this network and participate fully in its activities. Transactions in the public blockchain are transparent, everyone can see it, but it is not clear who made the transaction. Because this technology is open source technology.

Advantages

• The biggest advantage of a public blockchain is that it is independent, meaning that no third party is needed to operate the blockchain.

• This blockchain network is very strict in terms of transparency and security and the number of participating nodes does not affect the security of the blockchain.

Disadvantages

• One of the problems with public blockchain is that hackers can hack this blockchain and change all the activities of the blockchain to damage the network. Which is a very big threat to the blockchain.

• The process of public blockchain takes some time to complete the transaction.|

Hybrid blockchain

This blockchain combines the features of private and public blockchain. This blockchain is like a consortium blockchain. Because this blockchain has the features of private and public blockchain. This blockchain technology protects users' identities as long as users are engaged in transactions. Verification is done as required here but the transaction records of the users are not disclosed.

Advantages

• The biggest advantage of this blockchain is that the network of third party blockchains is open while protecting the privacy of the user. That is, the rules can be changed when needed.

• Transactions are much faster in hybrid blockchains and these blockchains provide better scalability than public networks.

Disadvantages

• The hybrid blockchain network is not completely transparent and the network is difficult to upgrade.

• There are some restrictions on participating in the network.

Consortium blockchain

The consortium blockchain is also known as the federated blockchain. This blockchain is like a hybrid blockchain where private blockchain and public blockchain are featured. This blockchain is not controlled by a single person. It is like a decentralized one that is authorized by more than one entity or organization. As it is an approved blockchain, it can only be used by members of the organization concerned.

Advantages

• Consortium blockchains also have much more scalability and security than public blockchain networks.

• The network operates through a well-organized governance structure and participants have access to control over their resources.

Disadvantages

• The biggest problem is the identity of the user is not hidden.

• Transparency like public blockchain is not entirely certain. That means the consortium blockchain is weak in terms of transparency.

2:- What are the benefits of blockchain?

• Transparency

One of the great achievements of blockchain is its transparency. It has shown a high level of transparency by becoming a decentralized network. In this technology, the transaction records are visible to everyone and the participants can easily see where all the information of the distributed ledger is recorded. Even once the transaction data is recorded, that data is never changed unchanged.

• Security

Transactions are recorded using advanced security in blockchain technology. Since the blockchain stores data in the form of blocks and the blocks are connected to each other in an activity called hash, it is impossible to decode or modify this hash at once.

• Transaction tracing facility

With the help of blockchain technology, it is easy to identify any transaction in any part of the world at any time because the record of every transaction is stored in blockchain technology no matter how many transactions are done in blockchain technology.

• Credibility

Blockchain technology can hack the database of all transactions, the source of the transaction details, the address and the amount of assets. Hackers cannot carry out their fraudulent activities because of this advantage.

• Extremely efficient and Speed

Blockchain technology is highly efficient and blockchain technology makes transactions very fast and even takes very little time to store data during the transaction. Also the transaction by the user is very very carefully and efficiently eliminated.

3:-Explain Blockchain Distributed ledger?

Distributed laser technology is a type of technology that creates a list of records of cryptographically signed and unalterable transactions. When there is a new transaction in the blockchain, it is updated in the distributed ledger for the record of that new recent transaction. In the case of public blockchain, this laser can be easily viewed by anyone from anywhere in the world. Laser technology protocols allow users in different locations around the world to transact and verify recorded information. This is a decentralized system. Since it is a decentralized system, it does not require the approval of any authority to view transactions in distributed laser technology.

I will explain the features of blockchain distributed laser technology below:

Security

Since in laser distributed in blockchain technology all transactions are coded by applying record hash operations. These codes are immutable and the hash quality information is also immutable. Therefore it can be said that lasers delivered in blockchain technology are much safer.

Record time

Each recorded time in the lasers is performed at the specified time of the data time and date which further increases transparency and security.

Unchanging

In blockchain technology, once a piece of information is recorded in a ledger's distributed ledger, that information cannot be deleted or altered by any third party.

Programmable as required

Programs can be tailored to the requirements of distributed lasers in blockchain technology. It works automatically when the program is created.

Accessibility and searchability

In blockchain technology any change in the data recorded in the lasers is visible to everyone. Here is always accessible to all users. All users will see changes in transactions and anything else.

4:-What Is Blockchain Double Spending and how Bitcoin handles this problem?

What Is Blockchain Double Spending?

This is evident from the double spending
Doubling and spending consist of these two words. Doubling up is the process of acquiring wealth by using the same amount of cryptocurrency twice. This means that if a person uses the same amount of cryptocurrency and takes more assets than required from a trader at the same time, it is double the cost. This is mainly done by hackers. The job of hackers is to gain some insight by gaining knowledge about blockchain all the time. When hackers start a transaction, they copy the transaction ID and repeat the same transaction. Basically hackers make multiple copies by deleting the transaction information when the transaction is over. Creating this copy is only possible with digital tokens. The information in this transaction will be a duplicate of the actual transaction. This is called a blockchain attack. Attacks associated with some blockchains are finney, sybil attack, vector76 attack, 51% attack etc.

How Bitcoin handles this problem?

Bitcoin is like any other digital cryptocurrency that carries the risk of double the cost. Bitcoin blockchain needs to be verified before any user can transact. In the past, bitcoin used to carry the risk of costing twice as much. But now Bitcoin currency does not bear the risk which is one of the best aspects of the universal acceptance of Bitcoin. To solve the problem of double spending of bitcoin, two processes called blockchain and validation process have been introduced. In these two processes, the same amount of bitcoin is used twice to check whether it is saved. Nodes are notified when two transactions are started using the same amount of bitcoin. If two transactions are started using the same amount of Bitcoin, if the nodes match with the first transaction, then the first transaction is allowed to be added to the blockchain. No transaction will be included in the blockchain until the transaction has been verified by the verifiers. Using this process eliminates the problem of doubling the cost of bitcoin blockchain.

5:- Practical + Theory, Visit Blockchain Demo and check section Blockchain, then explain in detail how Blocks Hashes Work in Blockchain, what will happen when any middle of the block gets changed, try to give screenshot for each possible details.

First we go to the website by entering this linksource

Next we will see a homepage. After coming to the homepage we will click on the blockchain option at the top of the screen. Next we already got five blocks. A closer look at the five blocks reveals that each block has its own distinct hash and nuns value. We will also see that the first hash started with zero which means it is valid.

The hashes of the blocks are given below:

Block 1 Hash:

000015783b764259d382017d91a36d206d0600e2cbb3567748f46a33fe9297cf

Block 2 Hash:
000012fa9b916eb9078f8d98a7864e697ae83ed54f5146bd84452cdafd043c19

Block 3 Hash:
0000b9015ce2a08b61216ba5a0778545bf4ddd7ceb7bbd85dd8062b29a9140bf

Block 4 Hash:

0000ae8bbc96cf89c68be6e10a865cc47c6c48a9ebec3c6cad729646cefaef83

Block 5 Hash:

0000e4b9052fd8aae92a8afda42e2ea0f17972ea67cead67352e74dd6f7d217c

From the screenshot below we can see that the hash of each block matches its previous hash. A closer look reveals that Block 2 has added Block 1 hash, Block 3 has added Block 2 hash, Block 4 has added Block 3 hash and Block 5 has added Block 4 hash.

What will happen when any middle of the block gets changed

We'll see what happens if we change something in the block. For this I have written @ns-porosh in the blockbox. We can see in the screenshot below what happened due to the change.

Due to the change in the first block only, we can see in the screenshot below that the hash value has changed in all the blocks.

Since each block is associated with the hash value of the previous block, we can see in the screenshots below that the hash value of all blocks has changed.

6:-What Is Race Attack in blockchain? OR What Is Finney Attack in blockchain? OR What Is Vector76 Attack in blockchain?

What Is Race Attack in blockchain?

Hackers attack the blockchain in a deadly way. Hackers usually carry many types of attacks, including race attacks. In this attack, hackers make two transactions at the same time. These attacks are a kind of double-cost attack. Hackers send bitcoin to two people at the same time without waiting for the transaction to be confirmed. In this way they make many transactions with the same assets. Since hackers want to transact the same asset by sending it to multiple addresses, the first asset will be deposited in a pool and a mine will accept it, confirming 1 transaction and deleting the rest. Since the same asset has been sent to the two, the person who accepts the currency and the transaction is confirmed will not be deceived. If he confirms the transaction without accepting the currency then he will be deceived. So buyers should accept payment before the transaction is confirmed and this attack can happen.

However hackers need to be much faster if they want to carry out this attack. This is why this attack is called race attack.

7:-Limitations/disadvantages of Blockchain

Blockchain has many qualities. However, there are some flaws in the blockchain.I will discuss some of the errors below:

1:-Scalability

Scalability is the biggest problem in blockchain. Usually the transaction is done depending on the crowd in the network. A blockchain network is a system that is open to all, so that new nodes are constantly added to the system. The nodes of the network will be connected so the speed of the network will be slower. So it can be said that blockchain scalability is not complete.

2:-Crime

Money earned illegally is managed through blockchain technology. If a person trades or transacts assets through blockchain technology, then the government of his own country cannot understand it. For this reason, many countries have banned the use of blockchain technology.

3:-Hack attack

Another major problem with blockchain systems is that they are not completely secure. There are many types of attacks on blockchain systems. Such as: Race Attack, Finney Attack, Vector 76 Attack etc. This attack is likely to cause damage to property.

4:-High price

All the hardware-devices and other devices used in blockchain are much higher in the market price and much more money is required to maintain the hardware-devices and other devices.

5:-Unchanging:

In the case of ordinary banks, the transaction can be changed if necessary, but in the case of blockchain, it is impossible to change the transaction.

Conclusion

Blockchain technology is a decentralized network that has achieved success through cryptocurrency transactions. All transactions that are blockchain technology are recorded. Blocks in a blockchain store transactions and distribute them to each other at all nodes connected to the transaction using distributed laser technology.The hash system in the blockchain records information from various nodes in the chain. This information cannot be changed like a database system. It is very easy to do business in different countries of the world through blockchain because transactions in blockchain technology are very fast. The cost of doing business through blockchain is much less. Above all, seeing the various benefits of blockchain, its popularity is increasing day by day.Thank you very much Sir @stream4u for this beautiful lesson.

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