Immutability: The Unchangeable Truth of Blockchain

Immutability is a property denoting the impossibility of being changed, especially over time.

What is immutability?

Immutability is the main defining characteristic of a blockchain. The term “immutable” implies that data cannot be changed or modified by anyone once it is created. The need for immutability in a blockchain network stems from the fact that all nodes must agree to the validity of the data before it is transmitted. The essence of using blockchain as a distributed ledger technology (DLT) is to ensure that no individual entity can make changes to records once they have been added to the blockchain.

It is about 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 changed retroactively without changing all subsequent blocks and network collusion.

How does a blockchain become immutable?

Cryptographic hashing is what makes a blockchain immutable. Hashing is an encryption method that takes plaintext of any length and creates a unique hash value. A hash value always has a fixed length, regardless of the properties of the input data from which it is created.

The hashing algorithm is very simple, but also surprisingly difficult to reverse. If you apply the SHA-256 hashing algorithm to the phrase " a fast fox jumps over a lazy dog", the result will be a 256-bit (32 characters) hexadecimal number of the form "9e107d9d372a5dcea0c3f78f5340d8d4". If you apply this algorithm to any other string of text (for example, your password), you will always get the same result (a 32-digit hexadecimal number).

For data integrity purposes, the hash can be used as a digital signature. When sending some data over the network, you can use the hash value as your fingerprint. When we receive the same data, we can calculate their hash and check if it matches our original fingerprint. If not, we’ll know that someone has tampered with our data during its transmission.

It should be noted that immutability does not guarantee that the data cannot be changed. Its purpose is simply to ensure that no data or records in the blockchain can be changed without consequence.

The benefits of immutability

The benefits of immutability relate to security, data integrity, auditability, and fraud prevention on the blockchain. With a traditional database system, if someone accesses the data, they can corrupt or destroy it. With blockchain, any changes to the data require that all nodes on the network accept it. For this reason, there is no risk of data loss in blockchain, and it is therefore considered immutable.

The immutability of blockchain technology ensures that the integrity of the data is protected. The integrity of the blockchain is confirmed by a simple recalculation of the hash value. A mismatch between the block data and its corresponding hash value indicates invalid transactions.

Due to immutability, an organization can create an unchallenged registry, which avoids complexity during audits. Blockchain is immutable due to cryptographic hashing. Any change or substitution of the chain will cause the entire network to be disrupted.
Related terms