Merkle Tree: Blockchain’s Cryptographic Hash Functions Beginner’s Guide
Beginner’s Guide To Blockchain’s Merkle Tree
“Merkle Tree” is a tech term for a basic blockchain construct, without which blockchain as we know it wouldn’t exist. In a nutshell, the trees accommodate prompt and secure validation of large data structures. Importantly, they are fundamentally able by design to cope with the foreseeably boundless data sets in blockchain technology.
In a less technical summary, Merkle trees are integral, enabling components of a blockchain construct, “running” blockchain transactions with immutability and accounting integrity. As cryptocurrencies develop into the future, Merkle trees will persist as a basic build within evolving blockchain-stroke-cryptocurrency systems.
Also known as “hash trees,” Merkle trees’ pedigree stems from the realm of computer or specifically cryptography science. A Merkle tree is a tree-like layout of protocols where every “leaf” node is labeled. A node is like an offshoot, and the leaves’ labels are the “hash” of a data block. “Hashing” is best described as “generating a value or values from a string of text using a mathematical function,” a great definition from Techopedia.
A further extrapolation in definition would be that hashing is one of a number of ways that security is ensured when messages are destined for a single, nominated recipient only. Coming back to the central tree, moving away from the “leaves,” every other node or locale that is not a leaf node is identified through labels that are the hash of the labels of its child nodes. That’s a mouthful, but with the picture of a large, branching tree in mind, it becomes easier to picture the architecture.
To conclude a basic definition, hash or Merkle trees make for swift, effective and secure verification of the constituents contained in large data structures. The hash tree is formed from the amalgamation of hash chains and lists. A Merkle tree is basically a snippet of code or a protocol that maintains blockchain’s integrity, picking up and sorting potentially big data along clear and potentially infinitely branching lines. Merkle trees are named after the man who patented the tech in 1979, the early computer scientist Ralph Merkle.
Merkle Trees In Blockchain
The existence or application of Merkle trees within blockchain technology has a number of beneficial repercussions. The trees allow blockchains to scale while maintaining and also verifying data integrity. The hash functions of blockchain are a cryptographic construct and the supporting technology of any Merkle tree.
Cryptographic hash functions are any functions in a system used to map and sort whatever data comes down the line. Although that sounds trivial, with blockchain builds, what comes down the line on Bitcoin, for example, may be substantial. Without the construct of a Merkle tree, the entire system as we currently know it might not collapse, but become dysfunctional to the point of an effective collapse.
The Merkle tree applies a hashing algorithm to any given data input. The ensuing “fixed length output” is what coders call the “hash.” These hashes come not just length-fixed, they also present as wholly unique to the individual transaction.
The protocol is also deterministic, meaning that repeated hashing of the same data input always gives the same result. Even a slight, nominal change somewhere in the input produces a different result. This might seem negligible, but it is in effect the very heart of the Merkle tree’s value, allowing as it does for virtual fingerprinting of data inputs. It is this incorruptible function of the tree that gives blockchain its immutability.
Merkle Trees In Action
Merkle tree architecture allows for the efficient management of randomly large data inputs, but it also has value due to its managing large amounts of data using a similar hashing protocol as that which is employed in verifying much smaller data inputs.
Again a seemingly small point, this reality is valuable as it makes for congruence and mathematical sense in a blockchain build. Merkle trees section off whatever large data they are faced with and essentially make fast work of potentially intimidatingly large data chunks. The tree also has easy inbuilt identification of any attempted or successful changes to the data at hand.
All of this results in what are known as “Merkle proofs.” What this implies is that a user can verify hashing consistency by sampling at any point up the hash tree. The user can confirm that all components are in the right place without resorting to viewing the entire hash set. Random sampling extrapolates into overall correctness, no matter where on the tree results are viewed. The user can essentially confirm that a data snippet is correct and consistent with the relevant “root hash” by sampling but a small snippet of the whole data set.
Blockchains are basically linked lists packed with data. There is also a “hash pointer,” a protocol that “points” to the immediately prior block on the chain. This is the basic setup that defines blockchain, literally a chain of interconnected transactional data blocks. The pointer is a combination of the previous block’s data hash and that block’s address.
The beauty of a blockchain construct also lies in way blocks of data are linked. Because of the format, each hash of the preceding block presents as a snapshot of the state of the entire blockchain, as all of the hashed data is amalgamated into a single block hash.
Bitcoin Merkle Trees
As an example, the cryptographic hash function used in Bitcoin is known as the SHA-256 algorithm, an acronym of “Secure Hashing Algorithm.” The output here is fixed at a length of 256 bits. There are many potential algorithms users can employ in a blockchain build, but the SHA-256 is the one Bitcoin uses.
On the Bitcoin blockchain, every block holds the total of the transactions of that block plus a block header. Miners distribute data to blocks through their mining activity subsequently hashed through the Merkle tree protocol. This generates the “Merkle root” that is captured within the block header.
It might sound like gibberish, but this design comes with many definite benefits. For one, the specific Bitcoin application of the Merkle tree means that “pruning” of the chain to optimize space saving. In a nutshell, what it all comes down to on the Bitcoin blockchain is that old blocks are able to be pruned while preserving what intel is needed to generate the Merkle proof.
The application of Merkle trees in diverse blockchain projects is fundamental. Although each differs in exact construct – with many more complex than Bitcoin, for example – the basic architecture is the same.
Merkle trees are also employed in other applications beyond blockchain, used as they are in a wide range of systems. Merkle trees are also important attributes in “distributed version control systems,” like IPFS and Git. The function of easily securing and verifying data integrity when transacting P2P between machines makes them indispensable in this realm.