SHA3 Hash Generator: SHA-3 and Keccak Variants

How to use the sha-3 hash generator

1. Type or paste your data into the Input field. Pick Hex bytes to hash raw bytes instead of text.
2. Select a variant: SHA3-224, SHA3-256, SHA3-384, SHA3-512, Keccak-256 or Keccak-512.
3. The hash updates as you type, as lowercase hexadecimal.
4. Copy the digest for use in your application or to compare with another source.

How SHA-3 works

SHA-3 uses the sponge construction rather than the Merkle-Damgard structure found in older algorithms like those produced by a sha256 hash generator. Data is absorbed into an internal state of 1600 bits through XOR operations, then squeezed out to produce the final digest. The rate sets how many bits are absorbed per permutation call: 1152 bits for SHA3-224, 1088 for SHA3-256, 832 for SHA3-384 and 576 for SHA3-512.

The permutation function applies 24 rounds of five transformations: theta, rho, pi, chi and iota. Because the internal state is much larger than the output, finding collisions requires roughly 2^n/2 operations where n is the output length in bits.

NIST SHA-3 vs original Keccak

The original Keccak submission to the NIST hash competition appended the simple suffix bits 01 before padding. When NIST standardized the function as FIPS 202 in 2015, it added two domain-separation bits, so SHA-3 hashes use the byte 0x06 where Keccak uses 0x01 (SHAKE uses 0x1F). For the same input, SHA3-256 and Keccak-256 therefore give completely different digests: the empty string gives a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a with SHA3-256 and c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 with Keccak-256.

Ethereum adopted Keccak-256 before FIPS 202 was final, and uses it for addresses, function selectors and event topics, which is why both variants remain relevant. If you need an Ethereum-style hash, choose Keccak-256, not SHA3-256.

NIST test vectors

These are the digests of the empty string and of "abc", the standard short test inputs in the NIST examples for FIPS 202. The last two rows are original Keccak, not SHA-3.

Choosing the right output size

Each SHA-3 variant offers a different security level. Collision resistance is half the output size: 112 bits for SHA3-224, 128 bits for SHA3-256, 192 bits for SHA3-384 and 256 bits for SHA3-512. SHA3-256 is the most common choice for general-purpose hashing, and SHA3-224 is only worth using where a shorter digest is a hard requirement.

SHA3-384 and SHA3-512 suit long-lived signatures, certificate chains and high-assurance uses. Unlike the broken MD5 and SHA-1, no practical attack on any SHA-3 variant is known. SHA-3 is not faster than SHA-256 in software on most CPUs; its advantage is a different design, not speed.

Common mistakes when using SHA-3

The most frequent error is confusing NIST SHA-3 with original Keccak. Because the padding differs, the same message gives unrelated digests. Confirm which one your target system expects before comparing hashes.

Another mistake is treating SHA-3 as a password hashing function. Like the SHA-512 family, SHA-3 is fast by design, so for passwords use a deliberately slow algorithm such as bcrypt or Argon2. To confirm a downloaded file matches its published digest, use the hash checker.

What this tool does not do: it does not offer the SHAKE128 and SHAKE256 extendable-output functions, it does not hash files (paste bytes as hex instead), and it does not produce keyed hashes such as HMAC-SHA3 or KMAC.

Worked examples