How the SHA-2 (SHA-256) Hashing Algorithm Works

SHA-2 (Secure Hash Algorithm 2) is one of the most popular families of hashing algorithms. In this article, we’ll walk through each step of the SHA-256 algorithm, which belongs to SHA-2, and show how it works with a real example.

Photo by Rowan Heuvel on Unsplash

What is a hash function?

If you want to know more about hash functions, you can read Wikipedia. But to understand what this is about, let’s remember the three main purposes of a hash function:

• ensure data integrity (invariance) check;
• accept input of any length and output the result of a fixed length;
• change data irreversibly (input cannot be obtained from output).

SHA-2 and SHA-256

SHA-2 is a family of algorithms with the general idea of ​​hashing data. SHA-256 sets additional constants that define the behavior of the SHA-2 algorithm. One of these constants is the output size. “256” and “512” refer to the respective sizes of the output data in bits.

We’ll look at an example of how SHA-256 works.

SHA-256 “hello world”

Step 1. Pre-processing

1. Let’s convert “hello world” to binary:

01101000 01100101…