# google/highwayhash

Fast strong hash functions: SipHash/HighwayHash

Repository: https://github.com/google/highwayhash
Canonical: https://ross.abutalabs.com/products/highwayhash
Language: C++
License: Apache-2.0
License Family: permissive
Archived: true
Last push: 2024-04-18T16:08:17+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 3850, "days_push": 867, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1605, forks 189 (observed 2026-08-28T04:05:10.309949+00:00)

## What it is
A C++ library providing fast, strong (well-distributed and unpredictable) hash functions: a portable SipHash implementation and HighwayHash, a SIMD-accelerated hash roughly 5x faster than SipHash with security claims. It supports 64/128/256-bit outputs, runtime CPU dispatch, and C-callable bindings.

## Use cases
- fast keyed hashing for hash tables
- replace weak non-cryptographic hashes with strong ones
- compute 64/128/256-bit hashes of buffers
- hash data at high throughput with SIMD
- generate checksum-like digests similar to sha1sum
- use SipHash from C code

## When to avoid
- you need a general-purpose cryptographic hash like SHA-256 for signatures or integrity verification
- you need streaming/incremental hashing of very large files
- you need a hash for non-security purposes where speed matters more than unpredictability (e.g. xxHash, MurmurHash)

## Facets
- artifact type: library
- maturity: maintenance
- function: cryptography, security, benchmarking, developer-tools
- domain: security, performance, developer-tools
- platform: windows, cpp, cross-platform
- tags: hash-functions, siphash, highwayhash, simd, keyed-hashing, c-plus-plus, algorithms, linux, macos

## Member repositories
- google/highwayhash (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:10.309949+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:52:16.930254+00:00, confidence not recorded.
  - readme: https://github.com/google/highwayhash (fetched 2026-08-28T04:05:10.309949+00:00, sha 932ff9896bd3)
- Data as of 2026-08-30T08:39:29.467469+00:00.