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Keccak-256 Hash Generator

Compute Keccak-256 — what Ethereum means by "keccak256", and not the same as SHA3-256 despite the size.

Input

Keccak-256

Enter something above to see the result.

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Keccak is not SHA-3

Keccak won the SHA-3 competition, but NIST changed the domain-separation padding before publishing FIPS 202 — from 0x01 to 0x06. Everything else is identical, and that one byte makes every digest different.

Ethereum had already shipped with the original padding, so `keccak256` in Solidity means Keccak-256, not SHA3-256. Hashing the same input with the wrong one is a silent failure: both give a plausible 32-byte value.

keccak256("")  = c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470
sha3-256("")   = a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a

Frequently asked questions

Which one does my library use?

If it is an Ethereum library, almost certainly the original Keccak. If it is a general crypto library and the function is called sha3_256, it is usually FIPS 202. Compare the digest of the empty string against the two values above.

Is Keccak less secure than SHA-3?

No. The padding change was about domain separation, not a weakness. Both have the same security level.

Related tools

SHA3-256 Hash GeneratorCompute a SHA3-256 digest. Immune to the length-extension attack that SHA-2 needs HMAC to work around.Keccak-512 Hash GeneratorCompute the original Keccak-512 digest.SHA-256 Hash GeneratorCompute a SHA-256 digest of text or a file — the default choice for checksums, signatures and content addressing.