The structure of SHA-3 is very different from that of SHA-1 and SHA-2.
The key idea behind SHA-3 is based on unkeyed permutations, as opposed to other typical hash function constructions that used keyed permutations.
Smaller Keys, Stronger Security (Part 2)
Keccak also does not make use of the Merkle-Damgard transformation that is commonly used to handle arbitrary-length input messages in hash functions.
A newer approach called sponge and squeeze construction is used in Keccak.
Different variants of SHA-3 have been standardized, such as SHA-3-224, SHA-3-256, SHA-3-384, SHA-3-512, SHAKE-128, and SHAKE-256.
SHAKE-128 and SHAKE-256 are Extendable Output Functions (XOFs), which are also standardized by NIST.
Analogous to a sponge, the data is first absorbed into the sponge after applying padding.
Why This Matters for Blockchain Technology
There it is then changed into a subset of permutation state using XOR, and then the output is squeezed out of the sponge function that represents the transformed state.
The rate is the input block size of a sponge function, while capacity determines the general security level: SHA-3 absorbing and squeezing function
Key Points to Remember
- Design of SHA-3 (Keccak) The structure of SHA-3 is very different from that of SHA-1 and SHA-2.
- The key idea behind SHA-3 is based on unkeyed permutations, as opposed to other typical hash function constructions that used keyed permutations.
- Keccak also does not make use of the Merkle-Damgard transformation that is commonly used to handle arbitrary-length input messages in hash functions.
- A newer approach called sponge and squeeze construction is used in Keccak.
Conclusion
Design of SHA-3 (Keccak) represents one of the many innovative layers that make blockchain technology so powerful and transformative. As distributed systems continue to evolve, a solid understanding of these core concepts becomes increasingly valuable — not just for developers, but for anyone building, investing in, or working alongside blockchain-powered systems.
Whether you are just starting your blockchain journey or deepening existing expertise, mastering these fundamentals gives you the tools to think clearly about decentralized systems and make smarter decisions in this rapidly evolving space.