HashesRecommended
SHA-3 (Keccak) and SHAKE
Cryptographic hash functions and extendable-output functions
How it works
SHA-3 is the Keccak algorithm, chosen in a NIST competition and published as FIPS 202 in 2015. It uses a sponge construction: input is absorbed into a large internal state and output is squeezed out, which is a completely different design from SHA-2. SHAKE variants can produce output of any length.
Sizes: SHA3-224, SHA3-256, SHA3-384, SHA3-512; SHAKE128 and SHAKE256 with variable output
Strengths
- Not vulnerable to length extension attacks.
- A structurally different backup in case a flaw is ever found in SHA-2.
- SHAKE is used inside the post-quantum standards ML-KEM, ML-DSA and SLH-DSA.
Weaknesses and known attacks
- Usually slower than SHA-256 in software without hardware support
- Less widely deployed than SHA-2
Use it for
- Integrity and signatures where SHA-3 is required or preferred
- Extendable output (SHAKE) in modern protocols
Don't use it for
- Password storage on its own
Exam tip
SHA-3 is not 'a newer SHA-2'. It is a different (sponge) design and it was standardised as an alternative, not a replacement.