blake3

README

BLAKE3

Pure Go implementation of BLAKE3 with AVX2 and SSE4.1 acceleration.

Special thanks to the excellent avo making writing vectorized version much easier.

Benchmarks

Caveats

This library makes some different design decisions than the upstream Rust crate around internal buffering. Specifically, because it does not target the embedded system space, nor does it support multithreading, it elects to do its own internal buffering. This means that a user does not have to worry about providing large enough buffers to get the best possible performance, but it does worse on smaller input sizes. So some notes:

• The Rust benchmarks below are all single-threaded to match this Go implementation.
• I make no attempt to get precise measurements (cpu throttling, noisy environment, etc.) so please benchmark on your own systems.
• These benchmarks are run on an i7-6700K which does not support AVX-512, so Rust is limited to use AVX2 at sizes above 8 kib.
• I tried my best to make them benchmark the same thing, but who knows? 😄

Charts

In this case, both libraries are able to avoid a lot of data copying and will use vectorized instructions to hash as fast as possible, and perform similarly.

For incremental writes, you must provide the Rust version large enough buffers so that it can use vectorized instructions. This Go library performs consistently regardless of the size being sent into the update function.

The downside of internal buffering is most apparent with small sizes as most time is spent initializing the hasher state. In terms of hashing rate, the difference is 3-4x, but in an absolute sense it's ~100ns (see tables below). If you wish to hash a large number of very small strings and you care about those nanoseconds, be sure to use the Reset method to avoid re-initializing the state.

Timing Tables

Small

Size	Full Buffer	Reset		Full Buffer Rate	Reset Rate
64 b	205ns	86.5ns		312MB/s	740MB/s
256 b	364ns	250ns		703MB/s	1.03GB/s
512 b	575ns	468ns		892MB/s	1.10GB/s
768 b	795ns	682ns		967MB/s	1.13GB/s

Large

Size	Incremental	Full Buffer	Reset		Incremental Rate	Full Buffer Rate	Reset Rate
1 kib	1.02µs	1.01µs	891ns		1.00GB/s	1.01GB/s	1.15GB/s
2 kib	2.11µs	2.07µs	1.95µs		968MB/s	990MB/s	1.05GB/s
4 kib	2.28µs	2.15µs	2.05µs		1.80GB/s	1.90GB/s	2.00GB/s
8 kib	2.64µs	2.52µs	2.44µs		3.11GB/s	3.25GB/s	3.36GB/s
16 kib	4.93µs	4.54µs	4.48µs		3.33GB/s	3.61GB/s	3.66GB/s
32 kib	9.41µs	8.62µs	8.54µs		3.48GB/s	3.80GB/s	3.84GB/s
64 kib	18.2µs	16.7µs	16.6µs		3.59GB/s	3.91GB/s	3.94GB/s
128 kib	36.3µs	32.9µs	33.1µs		3.61GB/s	3.99GB/s	3.96GB/s
256 kib	72.5µs	65.7µs	66.0µs		3.62GB/s	3.99GB/s	3.97GB/s
512 kib	145µs	131µs	132µs		3.60GB/s	4.00GB/s	3.97GB/s
1024 kib	290µs	262µs	262µs		3.62GB/s	4.00GB/s	4.00GB/s

No ASM

Size	Incremental	Full Buffer	Reset		Incremental Rate	Full Buffer Rate	Reset Rate
64 b	253ns	254ns	134ns		253MB/s	252MB/s	478MB/s
256 b	553ns	557ns	441ns		463MB/s	459MB/s	580MB/s
512 b	948ns	953ns	841ns		540MB/s	538MB/s	609MB/s
768 b	1.38µs	1.40µs	1.35µs		558MB/s	547MB/s	570MB/s
1 kib	1.77µs	1.77µs	1.70µs		577MB/s	580MB/s	602MB/s
1024 kib	880µs	883µs	878µs		596MB/s	595MB/s	598MB/s

The speed caps out at around 1 kib, so most rows have been elided from the presentation.

Documentation

Overview

Package blake3 provides an SSE4.1/AVX2 accelerated BLAKE3 implementation.

Index

• func DeriveKey(context string, material []byte, out []byte)
• type Digest
  • func (d *Digest) Read(p []byte) (n int, err error)
  • func (d *Digest) Seek(offset int64, whence int) (int64, error)
• type Hasher
  • func New() *Hasher
  • func NewDeriveKey(context string) *Hasher
  • func NewKeyed(key []byte) (*Hasher, error)
  • func (h *Hasher) BlockSize() int
  • func (h *Hasher) Digest() *Digest
  • func (h *Hasher) Reset()
  • func (h *Hasher) Size() int
  • func (h *Hasher) Sum(b []byte) []byte
  • func (h *Hasher) Write(p []byte) (int, error)
  • func (h *Hasher) WriteString(p string) (int, error)

Functions

func DeriveKey

func DeriveKey(context string, material []byte, out []byte)

DeriveKey derives a key based on reusable key material of any length, in the given context. The key will be stored in out, using all of its current length.

Context strings must be hardcoded constants, and the recommended format is "[application] [commit timestamp] [purpose]", e.g., "example.com 2019-12-25 16:18:03 session tokens v1".

Types

type Digest

type Digest struct {
	// contains filtered or unexported fields
}

Digest captures the state of a Hasher allowing reading and seeking through the output stream.

func (*Digest) Read

func (d *Digest) Read(p []byte) (n int, err error)

Read reads data frm the hasher into out. It always fills the entire buffer and never errors.

func (*Digest) Seek

func (d *Digest) Seek(offset int64, whence int) (int64, error)

Seek sets the position to the provided location. Only SeekStart and SeekCurrent are allowed.

type Hasher

type Hasher struct {
	// contains filtered or unexported fields
}

Hasher is a hash.Hash for BLAKE3.

func New

func New() *Hasher

New returns a new Hasher that has a digest size of 32 bytes.

If you need more or less output bytes than that, use Digest method.

func NewDeriveKey

func NewDeriveKey(context string) *Hasher

NewDeriveKey returns a Hasher that is initialized with the context string. See DeriveKey for details. It has a digest size of 32 bytes.

If you need more or less output bytes than that, use the Digest method.

func NewKeyed

func NewKeyed(key []byte) (*Hasher, error)

NewKeyed returns a new Hasher that uses the 32 byte input key and has a digest size of 32 bytes.

If you need more or less output bytes than that, use the Digest method.

func (*Hasher) BlockSize

func (h *Hasher) BlockSize() int

BlockSize implements part of the hash.Hash interface. It returns the most natural size to write to the Hasher.

func (*Hasher) Digest

func (h *Hasher) Digest() *Digest

Digest takes a snapshot of the hash state and returns an object that can be used to read and seek through 2^64 bytes of digest output.

func (*Hasher) Reset

func (h *Hasher) Reset()

Reset implements part of the hash.Hash interface. It causes the Hasher to act as if it was newly created.

func (*Hasher) Size

func (h *Hasher) Size() int

Size implements part of the hash.Hash interface. It returns the number of bytes the hash will output in Sum.

func (*Hasher) Sum

func (h *Hasher) Sum(b []byte) []byte

Sum implements part of the hash.Hash interface. It appends the digest of the Hasher to the provided buffer and returns it.

func (*Hasher) Write

func (h *Hasher) Write(p []byte) (int, error)

Write implements part of the hash.Hash interface. It never returns an error.

func (*Hasher) WriteString

func (h *Hasher) WriteString(p string) (int, error)

WriteString is like Write but specialized to strings to avoid allocations.