Cryptography is the process and method of ensuring data security, confidentiality, and integrity. Cryptography is essential for establishing strong machine identities and safeguarding machine-to-machine connections and communications. This blog will share a beginner’s guide to a cryptographic hash function.

1. What is a hash function?

Beginner's guide to cryptographic hash function

A hash is a mathematical function that maps an arbitrary length string (up to a predetermined maximum size) to a fixed length string, according to the National Institute of Standards and Technology (NIST). The strength, speed, and purpose of hashing algorithms vary. NIST published the Secure Hash Standard (SHS) in 2015, which includes secure hash algorithms (SHA). The recommended algorithms are SHA-224, SHA-256, SHA-384, and SHA-512, as stated in Federal Information Processing Standard (FIPS) Publication 180-4. All algorithms are iterative, one-way hash functions capable of processing a message and producing a condensed representation known as a message digest. The United States Government and non-governmental organizations use FIPS 180-4.

2. What does a hash function do?

We consider data confidentiality whenever we email or transmit financial data over the Internet. When we send data via email, we want to ensure that the message received by the intended recipient is intact and undamaged. With digitally signed communications, you’ll want to ensure no one tampered with the underlying content after signing. The hash function aids in confidentiality, data integrity, and authentication.

A hash function can help an organization achieve the four information security goals listed below:

  • Maintain data and file integrity.
  • Make secure authentication easier.
  • Organize content and files to improve efficiency.
  • Passwords should securely store in a database.

A hash function’s unique properties help secure data at rest or in transit. This is because they show whether data has been altered, changed, or removed. Hashing prevents an attacker from performing reverse engineering to determine the source of hashed data. Because a cybercriminal cannot easily convert the hashed value into plaintext using today’s computers, the plaintext is protected (while it is technically possible; it isn’t likely).

3. How does a hash function work?

Beginner's guide to cryptographic hash function

Hashing converts data mathematically into a value that is essentially a representation of the data. Data or a file is input into the hash algorithm. The hash algorithm’s output is the data representation, also known as the hash value or hash output. The hashing algorithm extracts a fixed-size bit string value from a file containing data blocks and converts this data into a shorter fixed-length value representing the original string.

Consider the following scenario: you need to copy data files from one computer to another over an open network. Hashing ensures that the copied file is identical to the source file. What makes this possible? To ensure that the two values are the same, the hash value of the original file can compare to the hash value of the copied file. The file has not been altered or changed if the same values are. If the values do not match, the difference in hash values shows that the copied file is not identical to the source file and may have been changed. 

The difference could be as simple as adding a comma. The avalanche effect describes the result of the additional comma, an essential property of the hash function because a slight difference or change completely changes the resulting hash value.


The hash function is a handy cryptographic tool. It can use to secure data and provide visibility into potential files and underlying data alteration or modification. Because of its unique characteristics, hacking prevents an attacker from using reverse engineering to view plaintext or original input data. Finally, when using digital signatures, the cryptographic hash function can combine with other cryptographic tools such as encryption to support origin authentication, data integrity, and signatory non-repudiation. If you are looking for a blockchain solution for industries, contact SmartOSC.

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