A property that defines the inability to be changed, especially over time.
It's the ability to record transactions such as contracts, sales, purchases, etc., in such a way that once they are added, the data in those records cannot be altered retroactively without the alteration of all subsequent blocks and the collusion of the network.
Cryptographic hashing is what makes blockchain immutable.
Hashing is an encryption technique that takes plaintext input of any length and produces a unique hash value. Hashes are always of a fixed length, regardless of the properties of the input they are based on.
The hashing algorithm is very simple, yet surprisingly difficult to reverse. For example, if you applied the SHA-256 hashing algorithm to the phrase "the quick brown fox jumps over the lazy dog", it would return a 256-bit (64 characters) hexadecimal number like "ebc637e1a3b4902dce844b8c1e1014f11ccb0d4e0240071aae71d453c3c509b5". If you were to apply this algorithm to any other string of text (for example, your password), you will always get the same output (a 64-character hexadecimal number).
The hash can be used as a digital signature for data integrity purposes.
It’s important to note that immutability doesn’t guarantee that data can’t be altered. Its purpose is to merely ensure that no data or record on a blockchain can be altered without consequences.
The benefits of immutability are related to security, data integrity, easy auditing, and fraud prevention on blockchains.
In a traditional database system, if someone gains access to the data, they can corrupt or destroy it. In a blockchain, any changes to data require that all nodes on the network adopt the change. This is why there is no risk of data loss in a blockchain and why it is considered immutable.
Blockchain immutability ensures the protection of data integrity. The integrity of a chain can be validated simply by re-calculating the hashes value. Any discrepancy between the block data and its corresponding hash value indicates invalid transactions.
Because of immutability, an organization can produce an indisputable ledger, which prevents them from facing complications during an audit.
Thanks to cryptographic hashing, blockchain is immutable. Any changes or alterations made to a chain will disrupt the whole network.
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