Why Is Immutability A Blessing For Recording An Unalterable History On Blockchain?
Blockchain and its applications are being adopted by many firms in various sectors. The emerging technology’s peer-to-peer transactions remove any third party from the transaction process. Blockchain also offers decentralization, which erodes power from a single authority and distributes it among users. But there is one more radical feature which makes Blockchain tech stand out from others — ‘immutability’.
In this blog, we will be discussing what immutability is, and how it works as a blessing for Blockchain technology.
By definition, immutability means something which is unable to be changed or is unchanging overtime. But in the language of Blockchain, it means that any data that’s been written on the Blockchain database is immune to change and no one can change it, not even the system administrator themselves.
Let’s take an example — in a private database, a regular user has read-only access which disables them from making any changes in the data. On the other hand, a system administrator with high privileged access can easily change the database in whatever way they please.
This is where Blockchain’s immutability steps in to make the data more reliable.
It works as a proof of authenticity of the data and imparts a sense of trust to the users. The person providing the data will have the confidence that it could not be altered by anyone, while the person receiving the data will be assured of its authenticity.This feature of Blockchain makes it an ideal choice for financial transactions.
We have discussed how adopting Blockchain can make databases immutable to any alterations, now, let’s discuss how it achieves that.
How Blockchain makes its database immutable?
Let’s start at the beginning; Blockchain is a decentralized digital ledger which already has some inbuilt business as well as technical criteria. Immutability of a Blockchain is achieved by two factors: — Hashes and Blocks.
Hash or a hash function is a mathematical function which changes any input data into a unique code which can be said to be its fingerprint. This fingerprint is called ‘Hash’. It works like an algorithm that takes input and changes it into a fixed length output representing its fingerprint of the data. There are many types of hash functions used in Blockchain. One of the common hash function is Secure Hash Algorithm- 256 bit (SHA-256).
There are two properties of a good hash function which makes it critical in a Blockchain –
1. If there are any changes in the input data, the output hash will change drastically as well as unpredictably.
2. It is really difficult to decrypt the hashes in order to obtain the original data.
Hashes are the building blocks of immutability and security in a Blockchain.
After hashes come Blocks, all the transactions in a Blockchain are bundled into Blocks. These blocks contain details about the transactions and also the details from the previous Block’s hash. This makes a chain of inter-connected Blocks — all of them are connected to each other through the hash details.
This is much better than traditional ledgers of transactions having page numbers. Anyone can easily make alterations to it by simply tearing out any page and replacing it with another page with slightly different transactions. The tear-out page will have no relevant data that connects it with the previous or the next page. Even if it does, it can be easily added to the altered page.
But this will not be the case in Blockchain as every Block will have details about the hash of the previous Block. Every Block will specify on which hash (Block) it is building, removing any need of block numbers. For examples- say there are 4 blocks naming Block A, Block B, and Block C.
· Block B will have hash details of Block A and will specify that it is building on Block A
· Block C will have hash details of Block C and will specify that it is building on Block B so on and so forth.
Here are some key features of blocks and hashes:
1. The hash from the previous is not a sequential number.
2. The contents of the block determine the hash of the block.Any changes to the content will change the hash too.
3. One can easily run some check on hashes and blocks as the data in Blockchains are internally consistent.
Let’s look at what happens if someone tries to copy the data of a Blockchain and tries to alter it.
What happens if the data is altered?
First and foremost, it requires a lot of computing power to de-crypt all the data in order to make any alterations. Even if someone is able to do that, here are some points that will help detect any tampering:
· The Block’s Hashes won’t match
The regulator should first re-calculate all the block hashes based on the block data. The hash provided should be valid and match the contents of the block. If the hashes don’t match with the content of the blocks then it will signify that the blocks have been tampered. To counter this, one has to re-calculate all the hash data and match it with altered content.
· The block’s chain will break
Whenever there is a change in the block, the hash with will change. This will disrupt the Blockchain as the block next to the tampered block will have the hash of the old block. For example: if there is a change in block 25, block 26 will have the hash details of the older block 25 which now no longer exist. To counter this, hackers will have to undertake the nearly impossible task of rebuilding and rehashing all the blocks after the tampered block.
Furthermore, there are some precautions or rules that make it impossible to rebuild a Blockchain. These rules differ from Blockchain to Blockchain. Even if someone manages to alter a Blockchain, the regulator will only have to check the hash of the recent block and match it with other copies of the Blockchain. Any mismatching in the hashes will lead to suspicion. In other words, it is extremely difficult for anyone to create a fake Blockchain.
From all the information above one can conclude that immutability in a Blockchain doesn’t mean that the data is immune to any kind of tampering but it means that altering data on an offline Blockchain is extremely difficult and nearly impossible on a live Blockchain. Even if someone tries to change it, the attempt can be easily detected by a regulator. This feature of Blockchain is what’s attracting many companies towards it.
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