Basics

What is a Hash value? Let’s take a deep dive

The data that is stored on blockchains is done so in the form of a series of numbers and letters that are referred to as a ‘hash’ value.

The terms cryptocurrency and blockchain seem to be inextricably linked with one another since the latter serves as the foundation for a vast majority of all digital assets in existence today. And while blockchains can function as digital ledger systems, consisting only of transactions that have been validated via community consensus, the data that is stored in them is done so in the form of a series of numbers and letters that are referred to as a ‘hash’ value. In this regard, the entire science of ‘cryptocurrency mining’ deals with miners working with hashes, but that’s a topic for a later day.

The term ‘hashing’ refers to the act of processing data from a block using a specific mathematical function/formula, which in turn results in the creation of a value output that is highly specific in nature. As a result, hashing can be used as a means of safely transmitting messages that may be intended for a particular recipient without the risk of any third-party tampering. 

When employed in the context of cryptocurrencies, transactions associated with any digital asset are processed using a hashing algorithm — Bitcoin, for instance, uses a particular one called the ‘SHA-256’ —  which gives an output of a specific length each time it is deployed. 

For example, SHA-256 (Secure Hashing Algorithm 256) will always deliver an output value that is 256-bits in size irrespective of how big or small the input may be.

Input MessageAssociated Hash Value for SHA 256 algorithm
Stop6c45cb72a36e63d522aa54ed8adbd7a29a989474f2f77e0458af8800564ef3cb
My name is Shaun Ryderf73ab0d88834284a379d15ecfca9abb31bff30177fc7087958998caf1b03b299
Hello and good morning, trials of the COVID 19 vaccine are now underway6daba11f2146956bcfd445125468ccee30b8a3562f474403f7f11521d8fe9c51

Though cumbersome at first glance, the point of this entire exercise becomes increasingly clear when one starts to deal with large input volumes because instead of having to recall the said information — which as mentioned earlier, could be quite lengthy — one can simply keep track of its associated hash with relative ease. 

Similarly, as pointed out earlier, the use of hashes makes the determination of its original message/input value fairly difficult to determine since any small change in the code can result in the creation of an entirely different hash, thus making it ideal for the secure relay of sensitive information.

Cryptographic hash functions (CHFs)

Even though standard hash functions are routinely used in computing systems for various security related tasks — such as data authentication, ensuring the integrity of relayed messages — they are widely considered to be weak from a cryptographic standpoint. Enter ‘cryptographic hashes’, which as the name clearly suggests, are a special class of hash functions that possess properties that make them ideal for facilitating cryptographic actions. Some of these properties include:

  • Computational Speed: They should be capable of processing outputs as quickly as possible otherwise they could make the system inefficient and possibly impractical to use.
  • Irreversible: They should not be reversible which is to say that the process via which a particular cryptographic hash value is generated should always be a “one-way function”.
  • No Leakage Possibility: There should be no scope of two different input messages ever coming up with the same hash value. 

When compared with regular hash functions, CHFs have a number of novel applications within the domain of information security such as authentication of digital signatures, message authentication codes (MACs), etc. Furthermore, they are widely used in relation to cryptocurrencies since they allow for transactions to be processed in a totally anonymous manner.

Key takeaways worth highlighting

  • A hash function is basically a mathematical algorithm that can convert data of any arbitrary size into a fixed array of numbers and letters.
  • Cryptographic hash functions are basically a niche’ subset of hashes functions that are commonly used to process transactions, relay messages in an anonymous manner.
  • CHFs serve as the backbone of any blockchain ecosystem since they seek to help meet the network’s encryption demands without overly burdening it.
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