SHA-3 Algorithm | cryptocurrencies, blockchains & live prices

SHA-3 (Secure Hash Algorithm 3) is the latest member of the Secure Hash Algorithm family, standardized by NIST in 2015 as FIPS 202. It is based on the Keccak algorithm and uses a sponge construction, fundamentally different from the Merkle-Damgård structure employed by SHA-1 and SHA-2. The sponge construction works in two phases: an absorbing phase where input blocks are XORed into a subset of the internal state and permuted, and a squeezing phase where output blocks are extracted from the state. SHA-3 operates on a 1600-bit state using the Keccak-f[1600] permutation, which consists of 24 rounds of five step mappings that provide thorough diffusion and confusion of the input data.

SHA-3 offers several important security advantages over its predecessors. Its completely different internal structure from SHA-2 provides algorithmic diversity — if a fundamental flaw were ever discovered in the Merkle-Damgård paradigm, SHA-3 would remain unaffected. The sponge construction inherently resists length extension attacks without requiring wrapper constructions like HMAC. SHA-3 supports multiple output lengths (SHA3-224, SHA3-256, SHA3-384, SHA3-512) as well as extendable-output functions (SHAKE128 and SHAKE256) that can produce arbitrary-length digests. While SHA-3 is somewhat slower than SHA-2 in software implementations on modern CPUs, it excels in hardware implementations where its simple bitwise operations enable compact and efficient circuits.

SHA-3 was selected through NIST's public hash function competition, which ran from 2007 to 2012 and evaluated 64 initial submissions. Keccak was chosen as the winner based on its large security margin, elegant design, and strong performance in hardware. In the cryptocurrency space, SHA-3 is used directly as a mining algorithm by a small number of projects, though its broader influence is felt through its adoption in various blockchain protocols for internal hashing operations. The algorithm serves as an important backup to SHA-2 in the global cryptographic infrastructure, ensuring that the world has a well-vetted alternative hash function ready for deployment should weaknesses in SHA-2 ever emerge.