SHA3-256 Hash Code Calculator

SHA3-256 (Secure Hash Algorithm 3 256-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.

SHA-3 is the latest member of the Secure Hash Algorithm (SHA) family, officially released in 2015. Unlike SHA-1 and SHA-2, which are based on similar mathematical structures, SHA-3 is built on a completely different design called the Keccak algorithm. It was not created because SHA-2 is insecure; SHA-2 is still considered secure, but SHA-3 adds an extra layer of security with a different design, just in case future vulnerabilities are found in SHA-2.

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 SHA3-256 Hash Algorithm

I'm neither a mathematician nor a cryptographer, so I'll try to explain this hash function in way that my fellow non-mathematicians can understand. If you prefer a scientifically exact, full-on math explanation instead, you can find it on many on websites ;-)

Anyway, unlike the previous SHA families (SHA-1 and SHA-2), which could be considered similar to a blender, SHA-3 works more like a sponge.

The procedure to calculate hash this way can be broken down to three high-level steps:

Step 1 - Absorbing Phase

• Imagine pouring water (your data) onto a sponge. The sponge absorbs the water bit by bit.
• In SHA-3, the input data is broken into small chunks and absorbed into an internal "sponge" (a large bit array).

Step 2 - Mixing (Permutation)

• After absorbing the data, SHA-3 squeezes and twists the sponge internally, mixing everything around in complex patterns. This ensures that even a tiny change in input results in a completely different hash.

Step 3 - Squeezing Phase

• Finally, you squeeze the sponge to release the output (the hash). If you need a longer hash, you can keep squeezing to get more output.

While the SHA-2 generation of hash functions are still considered secure (unlike SHA-1, which should not be used for security anymore), it would make sense to start using the SHA-3 generation instead when designing new systems, unless they need to be backwards-compatible with legacy systems that doesn't support it.

One thing to consider is that the SHA-2 generation is probably the most used and attacked hash function ever (particularly SHA-256 due to its use on the Bitcoin blockchain), yet it still holds. It will be a while before SHA-3 has stood up to the same rigorous testing by billions.