SHAKE128 Hash Generator (Extendable Output)
Generate SHAKE128 output of any length (8–16384 bits) from text, hex or Base64 in your browser. FIPS 202 extendable-output function, hex or Base64.
A multiple of 8, from 8 to 16384 bits.
Runs entirely in your browser. Your data is never uploaded.
What is SHAKE128 Hash Generator?
SHAKE128 is the SHA-3 extendable-output function with 128-bit security: instead of a fixed digest size you choose how many output bits you want. This tool computes SHAKE128 of text or raw bytes with a configurable output length (default 256 bits).
How to use SHAKE128 Hash Generator
- Type or paste your input into Text to hash — the digest updates as you type (an empty box shows the hash of empty input).
- Choose the Input encoding: Text (UTF-8) hashes the characters as UTF-8, Hex bytes or Base64 hash the decoded raw bytes.
- Set Output length (bits) — a multiple of 8 between 8 and 16384 (default 256).
- Pick the Output format (hex lowercase, hex uppercase or Base64) and click Copy.
Example
abc
5881092dd818bf5cf8a3ddb793fbcba74097d5c526a6d35f97b83351940f2cc8
SHAKE128("abc") with the default output length of 256 bits.
When to use SHAKE128 Hash Generator
Use SHAKE128 when a protocol specifies it (e.g. Ed448 uses SHAKE256, ML-KEM/Kyber and ML-DSA/Dilithium use SHAKE128/256), to derive a stream of pseudo-random bytes from a seed, or to get a hash of non-standard length. If you just need a regular hash, SHA3-256 or SHA-256 is simpler and more widely supported. For keyed use, prefer KMAC over hashing key and message together.
How SHAKE128 Hash Generator works
SHAKE128 is an extendable-output function (XOF) from FIPS 202. It uses the same Keccak-f[1600] sponge as SHA-3 with a capacity of 256 bits (rate 1344 bits) and the domain suffix 1111 (padding byte 0x1F). After absorbing the input, the sponge is squeezed for as many bits as requested, so the output length is a parameter rather than a property of the algorithm. Shorter outputs are prefixes of longer ones. Security is min(output/2, 128) bits for collisions.
Common Use Cases
- Reproduce SHAKE outputs from post-quantum algorithm specifications
- Derive a custom-length fingerprint (e.g. 128 or 1024 bits)
- Generate test vectors for a SHA-3 / XOF implementation
- Expand a seed into many pseudo-random bytes for testing
Security Note
SHAKE128 is a NIST-approved function with no known practical attacks. It is not a password hash and not a MAC by itself — use KMAC128 for keyed authentication. Everything runs locally in your browser.
FAQs
Is SHAKE128-256 the same as SHA3-256?
No. They share the Keccak permutation but use different capacities and domain suffixes, so outputs are unrelated.
If I ask for more bits, does the beginning change?
No. A longer SHAKE128 output is the shorter output followed by more bytes. For example the first 128 bits of SHAKE128("abc") are the 128-bit result.
Does a longer output make it more secure?
Only up to the 128-bit security level. Beyond 256 bits of output, collision resistance stays at 128 bits.