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SHA3-256 Hash Generator

Generate SHA3-256 hashes online instantly. NIST FIPS 202 SHA-3 standard, Keccak sponge construction. 256-bit output. Note: SHA3-256 is different from Keccak-256 (used by Ethereum). Supports HMAC-SHA3-256.

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Related Hash Tools

SHA3-256 FileHash from file Keccak-256Ethereum's hash SHA3-224224-bit SHA-3 SHA3-512512-bit SHA-3 SHA256256-bit SHA-2

Frequently Asked Questions

What is SHA3-256?
SHA3-256 is the 256-bit variant of SHA-3, standardized in NIST FIPS 202 (2015). It uses the Keccak sponge construction with a 1088-bit rate and 512-bit capacity, producing a 64-character hexadecimal digest.
SHA3-256 vs SHA-256 — which should I use?
Both provide strong 256-bit security. SHA-256 is more widely deployed. SHA3-256 is immune to length-extension attacks (SHA-256 is not). If you need FIPS 202 compliance or want the modern Keccak construction, use SHA3-256. For maximum compatibility, use SHA-256.
Is SHA3-256 the same as Keccak-256 (Ethereum)?
No. Ethereum uses Keccak-256, which is the original Keccak algorithm before NIST standardization. NIST added domain separation padding, so SHA3-256 produces different outputs than Keccak-256 for the same input. Use our Keccak-256 tool for Ethereum address derivation.
What is HMAC-SHA3-256?
HMAC-SHA3-256 is a keyed MAC using SHA3-256. It produces a 256-bit authentication tag. Note that SHA-3 itself is already resistant to length-extension attacks, but HMAC provides an additional layer of standardized key derivation.

About SHA3-256 Hash Generator

SHA3-256 is the 256-bit member of the SHA-3 family, standardized in NIST FIPS 202 (August 2015). It is built on the Keccak sponge construction, which uses a 5×5 array of 64-bit lanes (1600-bit state) and the Keccak-f[1600] permutation. SHA3-256 uses a 1088-bit rate with 512-bit capacity, absorbing input in 136-byte blocks and squeezing out a 256-bit digest.

SHA3-256 is NOT Keccak-256

This is one of the most common confusions in cryptography. When NIST standardized Keccak as SHA-3, they modified the padding scheme, adding a 2-bit domain suffix. As a result, SHA3-256 and the original Keccak-256 produce different outputs for the same input. Ethereum uses the original Keccak-256 (before NIST modification) for all address derivation and transaction hashing. If you need to hash Ethereum addresses, use our Keccak-256 tool instead.

Advantages Over SHA-256

SHA3-256 is immune to length-extension attacks because the sponge construction does not expose the internal state. SHA-256 (like all Merkle-Damgård constructions) is vulnerable to length-extension attacks unless HMAC or similar is used. SHA3-256 also provides a different algorithmic basis, offering diversity against potential future attacks on SHA-2.

Performance and Adoption

SHA3-256 is slower than SHA-256 on most current hardware without dedicated acceleration. However, many modern CPUs include SHA-NI instructions for SHA-256 but not SHA-3. For new applications requiring FIPS 202 compliance or post-SHA-2 planning, SHA3-256 is the recommended choice.