![0001-11992234853_20211111_091804_0000.png](https://cdn.steemitimages.com/DQmZmuStAqRZQ8i2kc2ZaHUizcwUzxv83Y3UmXd4rpLaUDf/0001-11992234853_20211111_091804_0000.png) [Source](https://canva.me/lbILESDo5kb)

![line rizki.png](https://cdn.steemitimages.com/DQmVWz8xx2tTVzDEdQesHV8aheevPJphHEkfNFwFGymeUj9/line%20rizki.png)

https://cdn.steemitimages.com/DQmTgC8Btd97Hx81bpV4wj88qQNSwTK84adkWyV7GZcZCN3/0001-7922856034_20210915_181226_0000.png

Dear steemian, I hope you are still not bored to have fun on steemit.

**Write the definition of blockchain. And how our data on Blockchain is protected from hackers. ? And write details about Data, Hash and Previous Hash tag and explain through screenshot.** **I chose the questions that I mentioned above to be done in this homework assignment, I hope I can answer the questions well. Thankyou Professor @yousafharoonkha for the lectures you gave us, greatly increased my knowledge of the Blockchain network.**

https://youtu.be/YZG7z4FOn0g [**Oasis - Don't Look Back In Anger**](https://youtu.be/YZG7z4FOn0g)

![line rizki.png](https://cdn.steemitimages.com/DQmVWz8xx2tTVzDEdQesHV8aheevPJphHEkfNFwFGymeUj9/line%20rizki.png)

Write the definition of blockchain.

![line rizki.png](https://cdn.steemitimages.com/DQmVWz8xx2tTVzDEdQesHV8aheevPJphHEkfNFwFGymeUj9/line%20rizki.png) Blockchain is a new technology developed for digital data storage systems, this technology is connected through cryptography. One of the characteristics of this technology is that the network does not have a central authority or better known as decentralization. Blockchain consists of two words namely Block and Chain, its name comes from the way blockchain works which uses computers to create interconnected blocks (chains) using cryptographic principles to execute all transactions. In short, it can be said that blockchain is a chain of blocks that stores information on transactions carried out within the blockchain network. ![blockchain-g49b78fa99_1280.png](https://cdn.steemitimages.com/DQmPwmJp4j8NekKkXap5YZS9ZLj2ui9V4UnhPhH5eQuEN3R/blockchain-g49b78fa99_1280.png) [Source](https://pixabay.com/id/vectors/blockchain-mata-uang-kripto-jaringan-3277336/)

Blockchain records information or transactions that cannot be changed because each block in the Blockchain will be connected to the previous block via a hash so that all informations in the Blockchain cannot be changed or deleted without changing the entire contents of the Blockchain. Every Block in the blockchain system is verified by millions of computers and then distributed using the internet network. These verified blocks are added to the chain and distributed in a special network, which is logged. Each block created consists of a ledger and three elements, namely data, hash, and hash of the previous block. ![What-is-blockchain-and-how-does-it-work-4.jpg](https://cdn.steemitimages.com/DQmPcNgEBsZq5LyLB5xqA4ARo49s835D6Ys9iEgcsHaFEE6/What-is-blockchain-and-how-does-it-work-4.jpg) [Source](https://www.ledger.com/academy/blockchain/what-is-blockchain)

Blockchain makes it easy for users to transact directly between two parties without the need for intermediaries or third parties such as banks. So that the transactions that occur are guaranteed transparency and also transactions are recorded neatly without any human or machine errors.

![line rizki.png](https://cdn.steemitimages.com/DQmVWz8xx2tTVzDEdQesHV8aheevPJphHEkfNFwFGymeUj9/line%20rizki.png)

How our data on Blockchain is protected from hackers.

![line rizki.png](https://cdn.steemitimages.com/DQmVWz8xx2tTVzDEdQesHV8aheevPJphHEkfNFwFGymeUj9/line%20rizki.png) One of the advantages of Blockchain is the security of the data that we store in the system. The data on the blockchain is securely protected from everything including hackers. Blockchain has always been recognized as a highly secure asset storage system, due to several important things about data security such as zero-knowledge storage, encryption, privacy, security and trust, all combined with a decentralized immutable ledger. ![blockchain.png](https://cdn.steemitimages.com/DQmTiZEvXAtvKw6cw6iwvEUDLejGBjMai66mguivcYVsEda/blockchain.png) [Source](https://scalar.usc.edu/works/farnham-research/media/31-aug)

The simplest blockchain principle is to give authority to each user to control the private key which is controlled by them, in other words we have the authority and control over all the keys that we have. It is highly recommended to save the key manually to avoid data theft by hackers if we store it in email or other networks that hackers might break into. What about the possibility of hackers directly trying to hack the Blockchain system directly? ![Bitcoin-hack-blockchain-wallet-hacking-800x600.jpg](https://cdn.steemitimages.com/DQmbCjy1MSG9CtBokKvzRoobzio6xCVicVtGarFaomyhfLM/Bitcoin-hack-blockchain-wallet-hacking-800x600.jpg) [Source](https://www.salvagedata.com/hacking-prevention-tips-ways-to-protect-your-device-from-hackers/bitcoin-hack-blockchain-wallet-hacking/)

Like I said before, changing or altering the data storage in the blockchain is an impossible process. When hackers want to steal information on the Blockchain by changing or deleting it is impossible to do without changing the entire contents of the Blockchain, because one block is connected to the previous block via a hash. So, blockchain is the most secure distributor ledger from everything including from the clutches of hackers. ![line rizki.png](https://cdn.steemitimages.com/DQmVWz8xx2tTVzDEdQesHV8aheevPJphHEkfNFwFGymeUj9/line%20rizki.png)

Write details about Data, Hash and Previous Hash tag and explain through screenshot.

![line rizki.png](https://cdn.steemitimages.com/DQmVWz8xx2tTVzDEdQesHV8aheevPJphHEkfNFwFGymeUj9/line%20rizki.png) **Data**

Blockchain is a safe place to store various information securely and immutable. This stored information is what we call data. Data is an important part of the blocks that make up the chain of blocks in the Blockchain system. As the purpose of blockchain is as the safest place to store data, so the existence of data becomes very vital in the Blockchain. For example in the Tron blockchain when we transfer TRX, the data in the block will be in the form of information about the sender, recipient, the amount of TRX we transfer and when we make the transfer. ![IMG_20211110_185810.jpg](https://cdn.steemitimages.com/DQmf7DcJGuni27uS3LeYFBUCgSowwt337ZufVJ5Mdr9Le2D/IMG_20211110_185810.jpg) **Screenshot from My TronLink**

In the screenshot above, we can clearly see that there is the sender's data in the form of my TronLink wallet address and the recipient's data in the form of my Upbit wallet address, and the amount of TRX that was transferred was 10.25 TRX. When the data becomes a component of a block in the blockchain network, then we cannot change the data again because the block will error automatically and the block becomes invalid. I tried changing the data by adding the word "DARK" in Blockchain Demo and immediately the block became invalid.

https://cdn.steemitimages.com/DQmcgHobKKWkXX3gTcjmEdFutMDZ2Zd1fzAGU3nHrm6jCxb/IMG_20211110_190623.jpg

https://cdn.steemitimages.com/DQmcf7LmrfWx5mfTqhrCduNwc7Bn3hArzzphoF4AV23kNfW/IMG_20211110_190439.jpg

[**Source**](https://andersbrownworth.com/blockchain/blockchain)

**Hash**

In cryptography, a hash is an algorithm used to convert information. Incoming data is processed into numbers, letters, or other characters into encrypted characters without changing its size. Blockchain also applies these cryptographic principles, in Blockchain Hash is a code that is in a Block that contains a series of unique words and letters that are certainly different from previous or future hashes. ![IMG_20211111_075712.jpg](https://cdn.steemitimages.com/DQmW28wm3CamGiNh5ZLijbrj7zFS4fR2MyxPXe6xvbqUmmQ/IMG_20211111_075712.jpg) [Source](https://andersbrownworth.com/blockchain/blockchain)

The existence of hashes in the blockchain is like fingerprints that cannot be the same for every human being, although sometimes they are somewhat similar but nothing is the same even though they are identical twins. Data that has been encrypted via a hash function can no longer be recovered, because this algorithm is known as a one-way function or one-way encryption. So we can no longer change the data that has been entered in the hash and has become part of the block. ![IMG_20211111_081611.jpg](https://cdn.steemitimages.com/DQmeNSMJdbmjhA7MiYc5TNp24Y6Et1sRwFBJwdSr242bMYz/IMG_20211111_081611.jpg) [Source](https://andersbrownworth.com/blockchain/blockchain)

**Previous Block Hash Code**

The previous block hash code is a series of hash codes from the previous block which automatically becomes part of the new block along with the newly created hash. Like the example given by Professor @yousafharoonkhan that blocks are like folders on our computer, when a folder is filled with data, we need a new folder to store more data. ![folders-gee705e4c3_1280.png](https://cdn.steemitimages.com/DQmRoKtHCPk6GcTLEkUvi7q5NMJRVyi8gR3bQi8rsY7rKho/folders-gee705e4c3_1280.png) [Source](https://pixabay.com/id/vectors/folder-mengatur-pemandangan-154471/)

When a new block is created, the hash code of the previous block is entered in the new block so that the hash code is in the new block and the previous block. Thus the previous block is connected to the new block in a chain which we know as Blockchain. ![IMG_20211110_174952.jpg](https://cdn.steemitimages.com/DQmc3QJb9MRqxZQ8neYAbqZkkhvyYkMrWfMyyDy8tHwm2sx/IMG_20211110_174952.jpg) [Source](https://andersbrownworth.com/blockchain/blockchain)

The screenshot above describes the parts of a block in a blockchain network. The hash code of the previous block and the new hash become components of the new block. The new block and the previous block are connected to each other in the form of a chain by the previous hash code, thus forming a decentralized blockchain. ![line rizki.png](https://cdn.steemitimages.com/DQmVWz8xx2tTVzDEdQesHV8aheevPJphHEkfNFwFGymeUj9/line%20rizki.png)

**That's my little understanding of Blockchain, of course, there are still many mistakes and shortcomings in this homework post. Thank you to my brothers at TSS who never get tired of guiding and directing me. You Are Amazing, Guys.**

**Best regard @rizkiblangpadang**

Wassalamu'alaikum

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