How do you hash a transaction?

The process of calculating the transactionsRoot hash within a blockchain involves a methodical approach. Initially, the hash value of each individual transaction (T) within the block is determined, denoted as H = hash(T). This step ensures that each transaction is uniquely identified and secured through cryptographic hashing.

Following the calculation of individual transaction hashes, the next stage involves pairing adjacent hashes and concatenating them together. This concatenated string then undergoes a second hashing process, producing a new hash value for each pair. For instance, if two hashes H1 and H2 are adjacent, the concatenated hash becomes H = hash(H1 + H2).

The concatenation and rehashing process is iteratively repeated, with each newly generated hash being paired with its subsequent neighbor and subjected to the same hashing function. This step-by-step method ensures that the integrity and authenticity of all transactions within the block are maintained and verifiable.

As the iteration progresses, the number of hashes being concatenated and rehashed decreases, following a binary tree-like structure. Each level of the tree represents a reduction in the number of hashes, ultimately leading to a single hash value at the top of the tree.

This single hash value, known as the transactionsRoot hash, represents the cumulative cryptographic fingerprint of all transactions within the block. It serves as a condensed and secure summary of the block's contents, enabling efficient validation and verification of the block's authenticity and integrity.