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the fastest(?) BLAKE2b implementation, in pure Rust with dynamic SIMD
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blake2b_simd Build Status


An implementation of the BLAKE2b hash with:

  • 100% stable Rust.
  • An AVX2 implementation ported from Samuel Neves' implementation. This implementation is faster than any hash function provided by OpenSSL. See the Performance section below.
  • A portable, safe implementation for other platforms.
  • Dynamic CPU feature detection. Binaries for x86 include the AVX2 implementation by default and call it if the processor supports it at runtime.
  • All the features from the the BLAKE2 spec, like adjustable length, keying, and associated data for tree hashing.
  • A clone of the Coreutils b2sum command line utility, provided as a sub-crate. b2sum includes command line flags for all the BLAKE2 associated data features.
  • no_std support. The std Cargo feature is on by default, for CPU feature detection and for implementing std::io::Write.
  • An implementation of the parallel BLAKE2bp variant. This implementation is single-threaded, but it's twice as fast as BLAKE2b, because it uses AVX2 more efficiently. It's available on the command line as b2sum --blake2bp.
  • Support for computing multiple BLAKE2b hashes in parallel, matching the throughput of BLAKE2bp. See update4 and finalize4.


use blake2b_simd::{blake2b, Params};

let expected = "ca002330e69d3e6b84a46a56a6533fd79d51d97a3bb7cad6c2ff43b354185d6d\
let hash = blake2b(b"foo");
assert_eq!(expected, &hash.to_hex());

let hash = Params::new()
    .key(b"The Magic Words are Squeamish Ossifrage")
    .personal(b"L. P. Waterhouse")
assert_eq!("ee8ff4e9be887297cf79348dc35dab56", &hash.to_hex());

An example using the included b2sum command line utility:

$ cd b2sum
$ cargo build --release
    Finished release [optimized] target(s) in 0.04s
$ echo hi | ./target/release/b2sum --length 256
de9543b2ae1b2b87434a730727db17f5ac8b8c020b84a5cb8c5fbcc1423443ba  -


The AVX2 implementation in this crate is a port of Samuel Neves' implementation, which is also included in libsodium. Most of the credit for performance goes to him. To run small benchmarks yourself, first install OpenSSL and libsodium on your machine, then:

cd benches/cargo_bench
# Use --no-default-features if you're missing OpenSSL or libsodium.
cargo +nightly bench

The benches/benchmark_gig sub-crate allocates a 1 GB array and repeatedly hashes it to measure throughput. A similar C program, benches/bench_libsodium.c, does the same thing using libsodium's implementation of BLAKE2b. Here are the results from my laptop:

  • Intel Core i5-8250U, Arch Linux, kernel version 4.18.16
  • libsodium version 1.0.16, gcc 8.2.1, gcc -O3 -lsodium benches/bench_libsodium.c (via the helper script benches/
  • rustc 1.31.0-nightly (f99911a4a 2018-10-23), cargo +nightly run --release
│ blake2b_simd BLAKE2bp │ 2.069 GB/s │
│ blake2b_simd update4  │ 2.057 GB/s │
│ blake2b_simd AVX2     │ 1.005 GB/s │
│ libsodium AVX2        │ 0.939 GB/s │
│ blake2b_simd portable │ 0.771 GB/s │
│ libsodium portable    │ 0.743 GB/s │

The benches/ script benchmarks b2sum against several Coreutils hashes, on a 1 GB file of random data. Here are the results from my laptop:

│ blake2b_simd b2sum --blake2bp │ 1.423 GB/s │
│ blake2b_simd b2sum            │ 0.810 GB/s │
│ coreutils sha1sum             │ 0.802 GB/s │
│ coreutils b2sum               │ 0.660 GB/s │
│ coreutils md5sum              │ 0.600 GB/s │
│ coreutils sha512sum           │ 0.593 GB/s │

The benches/count_cycles sub-crate (cargo +nightly run --release) measures a long message throughput of 1.8 cycles per byte for BLAKE2b, and 0.9 cycles per byte for BLAKE2bp and update4.

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