SHA-3 (Keccak)
SHA-3 is the hash standard based on the Keccak sponge construction; structurally entirely different from SHA-2, it serves as a fallback in case SHA-2 is broken.
Purpose
Provides an alternative hash structurally independent of SHA-2, increasing cryptographic diversity.
Mechanism
A sponge construction based on the Keccak-f[1600] permutation: in the absorb phase, input is chunked by the rate, XORed into the state, and permuted; in the squeeze phase, output is extracted from the state. Capacity c determines the security level. SHA3-256 outputs 256 bits.
Use cases
- NIST standard alternative hash
- Ethereum address hashing (Keccak-256)
- Crypto library diversity
- Length-extension-resistant scenarios
Examples
- Input
helloOutput1c8aff950685c2edc9a3d8b3e1c1c5...SHA3-256 output
Common errors
- Confusing SHA3-256 with Keccak-256 (different padding)
- Be explicit about the SHA-3 or Keccak variant
Related terms
SHA-256
SHA-256 is the 256-bit-output member of the SHA-2 family, widely used in TLS, blockchains, and cryptographic applications, with no known practical attacks. GLOSSARY
SHA-512
SHA-512 is the 512-bit-output member of the SHA-2 family; faster than SHA-256 on 64-bit platforms, providing a higher security margin. GLOSSARY
BLAKE2
BLAKE2 is a hash function designed by Jean-Philippe Aumasson et al.; faster than MD5 with security comparable to SHA-3, a high-performance alternative to SHA-2/3. GLOSSARY
BLAKE3
BLAKE3 further optimizes BLAKE2 with binary-tree parallelization; far faster than BLAKE2, it also supports XOF and MAC modes. GLOSSARY