A hashing algorithm is a mathematical function that garbles data and makes it unreadable.

Hashing algorithms are one-way programs, so the text can’t be unscrambled and decoded by anyone else. And that’s the point. Hashing protects data at rest, so even if someone gains access to your server, the items stored there remain unreadable. 

Hashing can also help you prove that data isn’t adjusted or altered after the author is finished with it. And some people use hashing to help them make sense of reams of data. 

What Is a Hashing Algorithm?

Dozens of different hashing algorithms exist, and they all work a little differently. But in each one, people type in data, and the program alters it to a different form. 

All hashing algorithms are:

• Mathematical. Strict rules underlie the work an algorithm does, and those rules can’t be broken or adjusted.
   
• Uniform. Choose one type of hashing algorithm, and data of any character count put through the system will emerge at a length predetermined by the program.
   
• Consistent. The algorithm does just one thing (compress data) and nothing else.
   
• One way. Once transformed by the algorithm, it’s nearly impossible to revert the data to its original state. 

It’s important to understand that hashing and encryption are different functions. You might use them in concert with one another. But don’t use the terms interchangeably.

How Does a Hashing Algorithm Work?

It's possible to create an algorithm with nothing more than a chart, a calculator, and a basic understanding of math. But most people use computers to help.

Most hashing algorithms follow this process:

• Create the message. A user determines what should be hashed.
   
• Choose the type. Dozens of hashing algorithms exist, and the user might decide which works best for this message.
   
• Enter the message. The user taps out the message into a computer running the algorithm.
   
• Start the hash. The system transforms the message, which might be of any length, to a predetermined bit size. Typically, programs break the message into a series of equal-sized blocks, and each one is compressed in sequence.
   
• Store or share. The user sends the hash (also called the "message digest") to the intended recipient, or the hashed data is saved in that form. 

The process is complicated, but it works very quickly. In seconds, the hash is complete.

What Are Hashing Algorithms Used For?

The very first hashing algorithm, developed in 1958, was used for classifying and organising data