SHA-512/256 Hash Code Calculator

SHA-512/256 (Secure Hash Algorithm 512/256-bit) is a cryptographic hash function that takes an input (or message) and produces a fixed-size, 256-bit (32-byte) output, commonly represented as a 64-character hexadecimal number. It belongs to the SHA-2 family of hash functions, designed by the NSA. It is really SHA-512 with different initialization values and the result truncated to 256 bits, to take advantage of the fact that SHA-512 runs faster than SHA-256 on 64 bit computers, but to keep the smaller storage requirements of 256 bit hash codes.

The outputs of SHA-512, SHA-256 and SHA-512/256 are completely different for the same input, so they are not compatible - i.e. it does not make sense to compare a SHA-256 hash code of a file to a SHA-512/256 hash code of the same file to see if it has been changed.

Full disclosure: I did not write the specific implementation of the hash function used on this page. It is a standard function included with the PHP programming language. I only made the web interface to make it publicly available here for convenience.

About the SHA-512/256 Hash Algorithm

I'm not particularly good at math and by no means consider myself a mathematician, so I'll try to explain this hash function in a way that my fellow non-mathematicians can understand. If you prefer the scientifically correct math-version, I'm sure you can find that on plenty of other websites ;-)

Anyway, let's imagine that the hash function is a super high-tech blender designed to create a unique smoothie from any ingredients you put into it. This takes four steps, three of which are the same as SHA-512:

Step 1: Put in Ingredients (Input)

• Think of the input as anything you want to blend: bananas, strawberries, pizza slices, or even a whole book. It doesn't matter what you put in - big or small, simple or complex.

Step 2: Blending Process (The Hash Function)

• You press the button, and the blender goes wild - chopping, mixing, spinning at crazy speeds. It has a special recipe inside that no one can change.
• This recipe includes crazy rules like: "Spin left, spin right, flip upside down, shake, chop in weird ways." All of this happens behind the scenes.

Step 3: You Get a Smoothie (Output):

• No matter what ingredients you used, the blender always gives you exactly one cup of smoothie (that's the fixed size of 512 bits in SHA-512).
• The smoothie has a unique flavor and color based on the ingredients you put in. Even if you just change one tiny thing - like adding one grain of sugar - the smoothie will taste completely different.

Step 4: Truncate

• By truncating (cutting off) the result down to 256 bits, we take advantage of the fact that SHA-512 runs faster than SHA-256 on 64 bit systems, but also keep the benefit of smaller storage requirements for 256 bit hash codes. Notice that the results are not compatible, SHA-512/256 and SHA-256 generate completely different hash codes.

I personally tend to stick to SHA-256, but maybe that's really just an old habit I need to get rid of. When designing new systems that will run mostly (or entirely) on 64 bit computers, SHA-512/256 seems like the better choice.