Blockchain, Decentralization, Block explorer - Steemit Crypto Academy Season 4 - Homework Post for Task 4

3개월 전




Good day Steemians!

This is my entry for the Steemit Crypto Academy Season 4 Beginners' Task 4. I have gone through the lecture by @yousafharoonkhan which was very interesting and stimulating, and so i will be answering Question 1 for this task.

(1) 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.

Let's dig in!





In the modern day world, almost everyone with access to the internet has heard or seen the word "Blockchain" somewhere before, but not many people actually know what it is, or the possibilities that come with this new technology. This technological marvel is the foundation for all cryptocurrencies, and can also be used for so much more than just that. So, what exactly is this Blockchain thing that everyone is getting so excited about?

A Blockchain is a peer-to-peer, distributed digital database/ledger that is secured and linked through advanced cryptography. To put in simpler terms, a blockchain is a list of records (called blocks), with each record being linked to the previous and next record through advanced cryptographic techniques, ensuring the authenticity and integrity of the records. These records (blocks) are linked to form a continuously growing list, much like a chain, hence the name Blockchain.



The first successful blockchain to be created and implemented was the Bitcoin blockchain, developed by Satoshi Nakamoto, the anonymous founder of Bitcoin. However, that was not the first time a blockchain had been thought about. In 1991, Stuart Haber and W. Scott Stornetta set the stage for what would later be known as the blockchain technology by creating a cryptographically secured database where no one could alter the timestamps of entries. In 2008, this idea was finally brought to life through Satoshi Nakamoto's Bitcoin.

What makes a blockchain so special?

Blockchains cannot be hacked or altered once an entry has been registered on the network. This means that any record that has been registered on the blockchain network is permanent. The permanency of records in a blockchain makes illegal actions impossible to carry out on the network, making a blockchain highly secure and verifiable.

But how exactly is the data on the Blockchain protected from hackers?

Blockchain technology works through cryptography, which refers to the various computer encryption algorithms and techniques used to create, manage and secure the blockchain network. With the use of cryptography, blockchains can have distributed trust networks. This eliminates the need for centralization, and allows any participant in the network to create records, without the need for authorization, or permission from a central body on the network. These records are then verified and approved by other participants in the network, and then recorded in a block, which is then saved and securely linked to the previous block, creating a chain.

There are two components of a blockchain. These are:

  1. The decentralized network: This is what enables decentralization in a blockchain and facilitate and verifies the records created an inputted on the ledger. With a decentralized network the software is not limited to one computer system. Rather, it can be managed on several computer systems.



  1. The indisputable ledger: This is the most important component of the blockchain and what makes a blockchain a blockchain. This is the list of records organised into blocks and connected to one another. These blocks contain three major elements:
  • Block Data: This is dependent on the type of blockchain, and what purpose the blockchain serves. For example, with Bitcoin the block data would be transaction data like: Sender, Receiver, Asset amount, etc. As blockchains can be used for so many other functions aside cryptocurrency, block data can also include things like medical records, location, distance, and so on.

  • Nonce: This stands for number only used once, and is a random number added to the contents of the blockchain in Proof-of-Work blockchains.

  • Hash: This is like the fingerprint of the block. It is computed through cryptography from all the contents of the block, and serves as an identifier of the block and block contents. It is generated in such a way that if any of the block contents is changed, it will become invalid, and the entire hash will have to be re-computed. It is always unique to each block.

  • Hash of the Previous Block: This is the unique identifier of the former block in the network, and is the essence of the blockchain technology. The previous block hash is unique to the previous block, and as such, adding it to the new block makes it part of the new block's contents. These contents, as explained earlier, will then be computed through cryptography to generate a the hash for the new block. Hence if the hash of the previous block is changed, the entire length of blocks after it become invalid.



Let's look at a practical example using Blockchain Demo

This is a site created by Anders Brownworth to show the basic blockchain operations.

Screenshot 2021-10-14 100627.png

Screenshot from Blockchain Demo

As we can see above, each block has the Nonce, Data, Previous Block Hash, and its own unique Hash. Take note of the Hash

If i change the Data of the first block, all the blocks turn red, showing that they are invalid.

Screenshot 2021-10-14 101851.png

Screenshot from Blockchain Demo

However, if i re-mine the first block, note that only it turns green. Also note that the hash has changed.

Screenshot 2021-10-14 102119.png

Screenshot from Blockchain Demo

This is because the hash has been recomputed because of the change in data, hence making the block valid. However, the next block remains invalid because it still contais the former hash of the old block 1 as its hash of previous block, and because this block is invalid, all the other blocks are invalid as well.

I will now re-mine the next blocks to change their hashes.

Screenshot 2021-10-14 102839.png

Screenshot from Blockchain Demo

Take note of the changed hashes.

This shows that records can not be tampered with once entered into the blockchain. This is how the blockchain protects data from hackers.



The blockchain technology is an amazing and revolutionary technology that has the potential to change the way the world works as a whole. It can be used in many different sectors and is very effective at securing data, and eliminating centralization. Hope you enjoyed reading!

-IamEl the ModestPoet

N/B: All pictures not cited, were designed by me using Canva, powerpoint, or gotten from the respective websites.

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Greetings @harryel, thank you very much for being a part of SteemitCryptoAcademy this fourth season and for your efforts in this 4th task of the fixed courses for beginners.

Your grade on this assignment is as follows:

Presentation Style (Markdown Usage)2/2
Following Standards (Guidelines)2/2
Quality of Content (Subject Matter Mastery)2/2
Spelling and Grammar (Writing Fluency)2/2



You have a lot of talent at the time of elaborating tasks, continue like this!

Thank you @harryel for your effort in carrying out this publication, I hope to continue reviewing your future tasks.