What is SHA-256?
The exciting world of the Internet is built on layers of algorithms, applications, encryptions to ensure function and multiple security protocols to ensure our identities aren’t stolen each time we open a website.
The endless possibilities that await us at the mere click of a button couldn’t occur sans the rapidly changing technology that created the online world we enjoy today. However, each time we stumble across another tech term cloaked in mystery for all but the most tech-savvy of us, we might just skip over the new vocabulary.
Yet the more we learn about the technology that keeps us online, the more we can protect our cybersecurity and avoid hackers and malware. SHA-256, or Secure Hash Algorithm 256-bit, is one such convoluted tech term that once broken down, is easily understood.
Let’s look at the definition of SHA-256, how a hash function works, the role of SHA-256 in cryptography and blockchain, and the role this algorithm plays in cybersecurity.
SHA-256 defined in easy-to-understand terms
Sadly, SHA-256 isn’t a new ‘droid in a Star Wars off-shoot, but its real-world function is still pretty cool. This algorithm falls under the umbrella of SHA-2, a category of cryptographic hash functions created by the NSA (National Security Administration) and published by NIST (National Institute of Standards and Technology) in 2001.
Each hash function in the SHA-2 category has a specific, yet similar, function that can help protect your cybersecurity. SHA-256 is a secure hash algorithm that allows applications and websites to include the following security measures:
- Password protection
- Digital handshakes
- Digital signature verification
- Prevention of reverse data engineering
- Protects against hash function collisions: In other words, it allows apps to distinguish between different hash functions.
How does SHA-256 work?
Imagine that hash functions are magical data blenders: Regardless of the data you pour into the SHA-256 blender, a 64-character, fixed-sized sequence of characters and numbers appears.
Thus, regardless of whether your data input is one sentence or the entirety of Finnegans Wake by James Joyce, the magical SHA-256 will use its cryptographic powers, blend it all together into a unique sequential code, and pour it into the Internet. This process then produces the hash value.
SHA-256 also protects your data from hackers who want to attempt to unencrypt it — the process only works with input, not output. Just as you can’t reach into a perfectly blended smoothie and pull out the blueberries that created it, you can’t unencrypt the data that SHA-256 transforms. Reverse engineering SHA-256 is virtually impossible.
What is a hash function?
Hash functions provide the basic foundational tools of current cryptography. According to NIST, a hash function is defined as “a function on bit strings in which the output is fixed.”
This means that only one specified string of data input can lead to a unique, specific outcome, and that there’s no way pre-specified output can be determined by input. Hash functions transform alphanumeric and numeric data to a smaller integer value, which allows data to be transferred concisely.
The steps of SHA-256
SHA-256 provides the foundation for security modules used daily online. The process of the SHA-256 hash function works through the following steps:
- Adds extra bits to the original data: SHA-256 adds a 1, followed by zeros, to secure the input data, and these added numbers should equal 64. The plaintext of your data message should now equal 512.
- Adds default values for your buffers. These buffer values initialize the SHA-256 hash function.
- Stores 64 keys that range from K to K 
- Breaks down the input data into multiple blocks that undergo 64 rounds of conversion
- Outputs the data in 256-bits
The role of SHA-256 in blockchain
For many people, the phrase “blockchain” is synonymous with cryptocurrency and with good reason — cryptocurrency wouldn’t exist without blockchain. Cryptocurrency wouldn’t be possible without SHA-256, either.
Bitcoin and other cryptocurrencies rely on SHA-256 to forge the unbreakable links between the blocks in a blockchain. Each SHA-256 link contains data from the previous block and bridges the gap between successive blocks on the chain. This ensures the integrity of the entire blockchain.
How SHA-256 improves cybersecurity
SHA-256 and other hash functions play an important role in cryptography — these hash functions are the unsung heroes of cybersecurity. “Hash” is the secret language that computers use to hide and protect our information; hash functions turn our data inputs into unique, scrambled codes.
You can think of SHA-256 as a lock with 2^256 possible combinations — the almost infinite number of possible keys used in its output encryption makes it extremely difficult to crack.
Here are some of the roles that SHA-256 plays in cybersecurity:
- Data integrity: Hash functions like SHA-256 create a unique fingerprint of the data you send via online files or messages. If even the smallest amount of data changes, the fingerprint SHA-256 creates will transform. Thus, SHA-256 can help you detect any attempted cyberattacks, errors, or tampering that may occur during transmission.
- Data storage: SHA-256 and other hash functions allow for quick data retrieval and organization in databases. A hash table is then formed that indexes data, helps secure data integrity, and allows for lightning-fast searches.
- Digital signatures: SHA-256 encrypts your data signature via hash, and allows easy verification that a document hasn’t been altered and was signed by the correct person.
- Password protection: When you create passwords to allow you access to website content, these websites store your passwords via “hash” rather than plain text. SHA-256 is the hash function that allows your passwords to remain secure and offers protection from hackers attempting to steal passwords.
Why the cybersecurity measures of SHA-256 matter
In a digital world where cybercriminals look for any way to hack into your life and steal your data, SHA-256 works silently in the background to protect your online activity. This hash function ensures that your data remains intact, your digital transactions are protected, and your passwords are secure.
This is a vital process as cyber crime can prove costly, regardless of the type of cyberattack that occurs.
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