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#38 in Cryptography

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RustCrypto: BLAKE2

crate Docs Build Status Apache2/MIT licensed Rust Version Project Chat

Pure Rust implementation of the BLAKE2 hash function family.


Fixed output size

use blake2::{Blake2b512, Blake2s256, Digest};
use hex_literal::hex;

// create a Blake2b512 object
let mut hasher = Blake2b512::new();

// write input message
hasher.update(b"hello world");

// read hash digest and consume hasher
let res = hasher.finalize();
assert_eq!(res, hex!(

// same example for Blake2s256:
let mut hasher = Blake2s256::new();
hasher.update(b"hello world");
let res = hasher.finalize();
assert_eq!(res, hex!("9aec6806794561107e594b1f6a8a6b0c92a0cba9acf5e5e93cca06f781813b0b"));

Also, see the examples section in the RustCrypto/hashes readme.

Variable output size

This implementation supports run and compile time variable sizes.

Output size set at run time:

use blake2::Blake2bVar;
use blake2::digest::{Update, VariableOutput};
use hex_literal::hex;

let mut hasher = Blake2bVar::new(10).unwrap();
let mut buf = [0u8; 10];
hasher.finalize_variable(&mut buf).unwrap();
assert_eq!(buf, hex!("2cc55c84e416924e6400"));

Output size set at compile time:

use blake2::{Blake2b, Digest, digest::consts::U10};
use hex_literal::hex;

type Blake2b80 = Blake2b<U10>;

let mut hasher = Blake2b80::new();
let res = hasher.finalize();
assert_eq!(res, hex!("2cc55c84e416924e6400"));

Minimum Supported Rust Version

Rust 1.71 or higher.

Minimum supported Rust version can be changed in the future, but it will be done with a minor version bump.

SemVer Policy

  • All on-by-default features of this library are covered by SemVer
  • MSRV is considered exempt from SemVer as noted above


The crate is licensed under either of:

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.


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