b2KIT

BLAKE2 Hash Generator

Generate BLAKE2b and BLAKE2s hash values with configurable digest length and key parameters.

Tested tool guide Tested browser tools Checked August 16, 2026

What BLAKE2 Hash Generator does, with a checked example

This tool computes BLAKE2b or BLAKE2s hash values for text or hex input, entirely in your browser. You can choose the digest length (as small as 1 byte) and provide an optional key, which turns the hash into a keyed MAC. The main surprise: BLAKE2 output size is variable, so changing the digest length yields a completely different hash, not just a truncated version of the same hash. Also, the tool does not prepend or interpret salt or personalization unless you provide them as part of the input.

Worked example

A concrete input and expected output from the current implementation.

Input

Text: hello world
Algorithm: BLAKE2b
Digest size: 32 bytes (256 bits)

Expected output

256-bit BLAKE2b hash of 'hello world' (hex): 256c83b297114d201b30179f3f0ef0cace9783622da5974326b436178aeef610

BLAKE2b with a 32-byte output is the standard BLAKE2b-256 variant. The given input 'hello world' (no newline) produces the hex digest shown, which matches the published test vector for BLAKE2b-256 of that string.

How the result is produced

1

Algorithm and output size

Select BLAKE2b (64-bit words, best on 64-bit CPUs) or BLAKE2s (32-bit words, for smaller or embedded targets). Specify an output length from 1 to 64 bytes (BLAKE2b) or 1 to 32 bytes (BLAKE2s). The tool computes the hash using the selected parameters and returns the digest as hex, with an option to show Base64.

2

Keyed hashing (MAC)

Optionally supply a key in text or hex. When a key is provided, the tool uses BLAKE2's keyed mode, which is a message authentication code. The key length must be between 1 and 64 bytes for BLAKE2b, and 1 and 32 bytes for BLAKE2s. Larger keys are rejected with an error message.

Good uses

  • Verify the integrity of a file or message by comparing its BLAKE2 hash with a published value.
  • Generate a keyed hash (BLAKE2 MAC) to authenticate a message between two parties who share the secret key.
  • Create a short, fixed-length fingerprint of a string for quick comparison or deduplication, choosing a digest size that fits your storage constraints.

Limits and checks

  • The digest length is a parameter that affects the internal state initialization, so different output sizes produce different hashes. For example, 'BLAKE2b-256' of a message is not a prefix of 'BLAKE2b-512'.
  • Input bytes are exactly what you type; if you paste a string with a trailing newline, the hash changes. There is no normalization of line endings or whitespace.
  • The keyed hash (MAC) is secure only if the key is secret and random. Using a short, guessable key (for example, a dictionary word) defeats the MAC's purpose.

Common questions

Is the hash computed locally or sent to a server?

Everything runs in your browser using JavaScript; your input never leaves your device. For sensitive data, this means no network transmission occurs. However, always close the tab if you are on a shared computer, as the tool does not clear its output fields automatically.

Why does BLAKE2s give a different hash than BLAKE2b for the same input and output size?

BLAKE2b and BLAKE2s are different algorithms with different internal word sizes and constants. They are not interchangeable; they produce entirely different digests for the same message and output length. Choose the one that matches the context you are working with (for example, a protocol that specifies 'BLAKE2s-256').

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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