Crypto Academy Season 3 | Advanced course : Let's Open The Blockchain. Course by @stream4u

Thanks you so much professor @stream4u, this course really give me more understanding about blockchain

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1. Definition of Blockchain, the types of blockchain and details explanation

Blockchain is a systematic way of keeping information in the way which makes it hard or not even possible to hack, change, or cheat

A blockchain is a digital record keeper of transactions that is copied and supply across the whole network of the computer systems on that blockchain.

There are different four types of blockchain which are Public, private, hybrid and consortium

Public Blockchain is the first type of blockchain technology. In this blockchain is where Bitcoin source from and still get it's popularity. It popularize distributed ledger technology (DLT). It get ride the difficulty that come along with centralization, and the less security and clarity. DLT don't save information in any one place, it share it across a P2P network instead. It's nature is decentralized, and it needs some method for substantiate the genuine of data.

Public blockchain has no restrictions, if you are with internet, you have access to it, you can sign on to any blockchain platform and be a permitted protuberance. As a user, you have access to both current and past records, and you can practice mining activities, the composite calculations are used to confirm transactions and add them to the record. In blockchain, there is no correct record or transaction that can be changed on the network, and anyone can check the transactions, find if there's any problem or introduce changes because the source code is always an open source.

Private blockchain is blockchain network that usually work in a limiting environment, it is a private network that is in control of a one entity. It is a private but it works like a public blockchain in a way that it also uses peer-to-peer union and also decentralize, but it is is on a very small scale. Anyone isn't permmited to join and prepare a calculating power, private blockchains works on small networks, like inside a company or organization. They are also known as enterprise blockchains.

Hybrid blockchain At times, companies or firms need the best of the worlds, and they will make use of hybrid blockchain. It's a type of blockchain technology that bring the elements of both private and public blockchain together. It allows companies start a private allow-based system with a public without permission system, it permit them to be in control of who can have access to some specific data that is being stored in the blockchain, and the data that will be open for public.

Consortium is the fourth type of blockchain, we can still call it federated blockchain, it is similar to hybrid blockchain in the sense that it has the features of both private and public blockchain but it is different in the more than one organizational members work together on a network that is decentralized. In essence, consortium blockchain is a private blockchain that has limited access to a group, it get ride of risks that come with one entity that is in controll of the network on a private blockchain

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2 Benefits of Blockchain

Blockchain benefits are many but i will mention 10 which are; ** Innovation, Trust, Decentralized structure, Improve security and privacy, cost reduction, speed, visible and traceable, immutable, Tokenization, individual control of data**

Innovation The Leaders in multiple companies explores and implements the blockchain system to find solution to problems that's untraceable and improve longstanding vexatious practices. Place cited the use of blockchain to confirm the information on job applicants hired as an example of such innovation.

Trust Blockchain makes two different entities have trust in themselves, and anywhere that trust is, business would engage. The blockchain value is obviously in any case of blockchain use that made easier transactions between entities that didn't have direct relationships but they still had to share data or payments.

Decentralized structure. When central actor that would enables trust is absent, when participants don't have trust in each others because they didn't know each other, blockchain allow data sharing within the businesses environment where none of the entities is exclusively in charge.

Improve Security and privacy privacy is one of the leading importance of the blockchain technology. The enhanced security introduced by blockchain generates from how the technology works. Blockchain makes an irrevocable record of transactions with end-to-end cryptogram, which disallow fraud and no authority activity.

Cost Reduction. it's one of the Blockchain's nature to reduce costs for firms. It provides intended task in processing transactions. It also limit manual works and ease reports and auditing processes.

3 Blockchain Distributed ledger

It's a information that is permitted to be shared and combined from two or more sites, institutions, or environments, it's easy to approach by multiple people. It let's transactions have public attestation. Those that participate in each knot of the network have access to the recordings that is shared across that network and they can own the same copy of it. If any change or additions made to the record, it would reflect and be copied to all participants in a moment

Advantages are;

• Blockchain Distributed ledgers allow information to flow easily, the process that makes a financial transactions easy to follow for accountants or auditors when they perform the reviews of financial statements. This process helps to get ride of the possibility of theft to happen on the in company. It reduce the use of paper and also help to the environment.

• The Centralized ledgers are liable to internet attack, but distributed ledgers are naturally hard to attack because all of the copies distributed have to be attacked at the same time before the attack can be successfully made. Besides, records don't change by a party. So it's hard to manipulate and attack, Blockchain distributed ledgers give room for great extent transparency.

• Blockchain Distributed ledgers reduces lack of intended task, it minimise time that transaction takes to complete, transactions are automated, and they works anytime, and minimise costs for the parties that make use of them.

4 Blockchain double spending

It is adposition flow in a currency scheme that the same single token can be spent more than one time. Not like cash that is physical, it is a digital token that has digital file that can be copied or spurious. just like fake money, double spending leads to expansion by making a new same amount of copied currency that did not exist before. It reduce the value of the currency that relates it relates with

Bitcoin handles the double-spending problem by making use of a confirmation control and maintaining a worldwide ledger called blockchain.

Bitcoin still maintains a earliest-ordered, variable containing the date transaction record from the early start of its operation in 2009. Every 10 minutes, a block is added to the record and all knot on the Bitcoin network record a copy of this global ledger global ledger which is the blockchain.

5 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.

• Hash look like a random numbers

• Hash changes whenever letter is type or changed in the box

• Hash is a fingerprint of datas

• E3bo starts with has that has nothing written in the box

• Regardless of how many letters or numbers written in the box, hash don't long more than it has

*Hash changes If you type in the box but If you type none existence letter in the box, the background colour changes to red unless you press mine and it correct itself

• Block is exactly like Hash but it has sections while hash has two sections

• Once a letter is signed is written in the data section, the Hash won't start with four zeros and the background colour would change to red

• If you didn't get it right, you can just click on Mine and it would make the correction itself; it would start with four zeros and Nonce number would change

• The blocks are 5, the first one looks like fake because it has four zeros

• If you make any changes in just a block, you have to make change in all the blocks by remine all the rest of the chain

• While adding the key, the keys look like random numbers and the private keys should be known only to you, don't tell anyone, through the private key, you can create public key that you can give to anyone

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

A race attack is carried out when an attacker makes two incompatible transactions. Like when a transaction is sent to the one it affect, he/she accepts the payment and didn't wait for the confirmation of the transaction. At the same time, a contending transaction returning the same amount of coin to the on that attack is cast to the network, in the end making the first transaction not valid.

Vector76 is a combine two past attacks. A harmful miner makes two nodes, one of the nodes is connected to the exchange node only and the other one have close connection with peers in the blockchain network. After that, the miner perform two transactions, one low value and one high-value. So, the attacker remine and keep a block with a high transaction from an exchange service. After a block is announced, the attacker emediatly sends that premined block to the exchange service.

It is possible when a hacker is in control of 51% of the network hash rate and makes a different fork that takes priority over the existing one. This attack was known as blockchain vulnerability at the beginning and it seemed not realised

Finney attack happens when you receive payment at zero confirmation. The accomplishments of this attack needs a miner that has mined a block but not yet cast it to the rest of the network. In this attack, the miner could add a transaction of payment from address one address to another one into the block already mined.

7 Disadvantages of Blockchain.

• Not a distributed computing system

• Scalability issue

• Some of their solutions consume energy

• They are inefficient at times

• Not completely secure

Blockchain is not a distributed computing system : Blockchain is a network that depend on nodes if it would function well. Quality of the nodes would determine the quality of the blockchain. Good example is Bitcoin’s blockchain, it is strong and encourage the nodes to take part in the network.

Scailability issue Blockchains are not scalable as the one that look like them centralized system. If you are a Bitcoin network user, you would discover that the transactions are finished, it depend on the network hindrance. This problem relate with scalability difficulty with blockchain networks.

Some of their solutions consume energy : Blockchain was first introduced with Bitcoin. It is using the Proof-of-Work general agreement algorithm which depend on the miners to do the tough work. Miners are encourage to give solution to complex mathematical problems, so the much energy it consume is what makes these composite mathematical difficult not so perfect for the real world.

They are inefficient at times : There are many blockchain technologies now. If you take the most popular ones that include the blockchain technology by Bitcoin, you will find lack of efficiencies in the system.

Not completely secure : Although Blockchain technology have more security than other platforms. Nevertheless, it does not mean that it is not secure completely but there are ways which the blockchain network can be compromised. The 51% attach, double spending, cryptographic cracking, and DdoS's attack are the problem that makes blockchain not secure at time

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8 conclusion

Whatsoever that is decentralized is the best and what the world need, not want is centralized, in control of someone or an entity. Blockchain is decentralized, but the public one. Even the private one is decentralized, just that it's useful for a firm or company. So for anyone hacker to hack the whole blockchain, the hacker would need to hack many chains which is too tough to do and even if that happens, there would still be a way to restore it back and Fork is one of them