Hashing is a fundamental technique in cybersecurity. When sending information through an open network, there’s always a risk of bad actors altering the message’s content before it reaches its intended destination. However, decentralized networks, such as blockchain, offer a promising solution. A unique signature is necessary to ensure the authenticity and originality of data sent or received.

But how can one create a unique signature suitable for datasets of varying types and sizes? The answer lies in hash values, which are generated through the hashing process, offering a robust solution to this challenge.

What Is Hashing?

Hashing is a fundamental cryptographic process that converts an input of any length, often referred to as a “message,” into a fixed-length string of bytes. This transformation is achieved through a mathematical algorithm known as a “hash function.” The primary objective of hashing is to uniquely identify data. The resulting hash value, often simply called a “hash,” serves as a digital fingerprint for the input data.

In simpler terms, imagine hashing as a one-way street. You can feed any amount of data into the hashing function, but the output will always be a fixed-length string of characters, regardless of the input’s size. This fixed-length output, the hash value, is like a unique identifier for the input data.

Top 3 Components of Hashing

Understanding the fundamental components of hashing is essential for anyone looking to grasp the intricacies of data structures and algorithms. The three primary components of hashing are the: key, hash function, and hash table.

1. Key: The key serves as the cornerstone of hashing, representing the original piece of data that needs to be stored or retrieved. In data structures like hash tables, the key acts as a unique identifier, determining the index where the corresponding data value will be stored. This ensures that each piece of data has a distinct location within the hash table.
2. Hash Function: This mathematical algorithm accepts the key as input and provides an index where one should store or retrieve the associated value. Its primary purpose lies in distributing the keys evenly across the hash table, minimizing collisions, instances where multiple keys generate the same index. A well-designed hash function ensures efficient data retrieval by consistently providing unique indexes for different keys.
3. Hash Table: Sometimes called a hash map, the hash table is a data structure that implements an associative array. It stores and retrieves data using key-value pairs. The hash function takes the key, processes it, and provides an index in the hash table where the system stores the corresponding value. If designed and managed well, hash tables enable constant-time average complexity for search operations.

SHA 256: The Secure Hash Algorithm

The Secure Hash Algorithm (SHA 256) is one of the most robust cryptographic hash functions currently available. Cryptographic hashes act as digital signatures for data sets. A cryptographic hash function (CHF) generates a cryptographic hash. This specialized function has several properties that make it a secure hash function for cryptography. To consider a cryptographic hash function secure, it must have the following characteristics:

• Quick Computation and Compression: The hash function should be able to quickly calculate and compress data regardless of the input size and produce a fixed-length hash value. Notably, the output’s length shouldn’t correlate with the input’s size.
• Deterministic Nature: The same input data must always produce the same hash value. If the hash value changes for the same data set, verifying data authenticity will be unreliable. However, consistent hash values make it easier to keep track of input data.
• Collision Resistance: It should be difficult or nearly impossible to find two different input data sets that produce the same hash value.
• Pre-Image Resistance: Finding the input data from the output hash value should be computationally hard. This makes it difficult for hackers to reverse the hash value to obtain sensitive information.
• One-Way Functionality (Non-reversibility): The process cannot be reversed to obtain the original input data from the hash value. While old hash functions such as MD5 and SHA1 have become reversible due to increased computing power, advanced cryptographic hash functions like SHA256 and SHA512 remain non-reversible.
• Non-predictable: Neither the input data nor the original message should predict the generated hash value.
• Diffusion or Avalanche Effect: Minor changes in the input data should lead to significant changes in the hash value. Even capitalization or digit changes should result in more than a 50% change in the output hash value.

Exploring Hashing with MD5 and SHA-256 Calculators

MD5 Hash Calculator

The MD5 Hash Calculator serves as an excellent tool to understand hashing. It demonstrates how different inputs are transformed into distinct hash values:

These examples highlight hashing’s unique capability: generating fixed-length, unique hash outputs from various inputs. This feature is crucial for maintaining data integrity and security in digital environments.

SHA-256: Enhancing Security in Blockchain

SHA-256, a robust cryptographic hash function, is essential in blockchain technologies like Bitcoin. It excels in processing large data volumes, converting extensive inputs into manageable, fixed-size hashes. This efficiency is crucial in handling complex transactions within the blockchain.

The strength of SHA-256 lies in its sensitivity to input changes. Even a minor alteration, such as a change in letter case, results in a completely different hash value. Observe these examples using the SHA-256 hash calculator:

The sensitivity of the hashing process is evident in the fact that a single character change in the input results in a completely different hash value. This consistency ensures that the hash value remains the same regardless of the number of times the input is entered. This unwavering nature is a cornerstone of blockchain technology, enabling effortless verification of data integrity and authenticity.

Blockchain technology makes data on the blockchain immutable, causing any unauthorized modifications readily detectable. This feature is essential for safeguarding the integrity and security of blockchain-based transactions.

What Are Hashed Identifiers?

Hashed identifiers play a crucial role in systems that prioritize privacy. These systems use hashing to transform sensitive data, like usernames or email addresses, into unique, unrecognizable identifiers. This transformation plays a vital role in safeguarding the original data. Even in the event of a data breach, the integrity of the raw data remains intact, shielded behind its hashed counterpart.

The concept of hashed identifiers can be illustrated using the scenario of user account creation. Instead of storing a user’s email address directly, the system generates a hash value by applying a hash function to the email address. When the user attempts to log in, the system again applies the hash function to the entered email address and compares it to the stored hash value. If the two hash values match, the login is successful. This approach ensures that even if a malicious actor gains access to the database, they only encounter the hashed values, not the actual email addresses.

In essence, hashed identifiers serve as a protective barrier, shielding sensitive data from unauthorized exposure. They find widespread application in various domains, including user authentication, data storage, and privacy-preserving messaging.

Conclusion

Cryptographic hash functions can further protect data integrity. If you question the authenticity or receive a different variant of data, you can process all received data through the cryptographic hash function. Then, compare the resulting hash value with the published one.

For example, when Microsoft releases free software available for download from multiple websites, Microsoft isn’t the sole custodian of this software installer. Other developers might modify it. To avoid malware or compromised software installers, a user should generate a hash value for each copy of the software downloaded. They can then compare it with the hash value provided on Microsoft’s official website.

Blocks in a blockchain apply a similar procedure. Each new block stores the hash value of the previous block to maintain the chain and safeguard the integrity of all preceding blocks. If someone alters a block, its hash value changes. This discrepancy means the next block won’t match the altered block because their hash values don’t align. To achieve alignment, one must also modify the subsequent block. However, changing that block also changes its hash value, necessitating changes to the next block, and so on. The same scenario will play out for the hundreds and thousands of blocks on that blockchain (blockchains like Ethereum have millions of blocks). Repeating this process for all linked blocks is practically impossible. 

At their core, hash values might appear straightforward. However, they serve as the backbone of the blockchain system, crucially ensuring data remains intact and resistant to tampering.

Identity.com

Blockchain is the future, and it is impressive to see Identity.com contributing to this desired future through the Solana ecosystem and other Web3 projects. Also, as a member of the World Wide Web Consortium (W3C), the standards body for the World Wide Web.

Identity.com, as a future-oriented company, is an open-source ecosystem providing access to on-chain and secure identity verification for businesses,  giving their customers a hassle-free experience. Our solutions improve the user experience and reduce onboarding friction through reusable and interoperable Gateway Passes. Please refer to our docs about how to help you with identity verification and general KYC processes.