# cloudflare/circl

CIRCL: Cloudflare Interoperable Reusable Cryptographic Library

Repository: https://github.com/cloudflare/circl
Canonical: https://ross.abutalabs.com/products/circl
Homepage: http://blog.cloudflare.com/introducing-circl
Language: Go
License: NOASSERTION
License Family: other
Topics: go, golang, post-quantum, cryptography, dilithium, ed25519, ed448, csidh, sidh, kyber, circl, elliptic-curves, hpke, pki, fips203, fips204, ml-dsa, ml-kem
Last push: 2026-08-24T14:00:22+00:00

## Health v2 (maintenance only)
Score: 94/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 84, longevity 100
- inputs: {"age_days": 2916, "days_push": 9, "days_rel": 28, "gap_med": 90.0, "n_releases_24m": 7}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1710, forks 219 (observed 2026-08-28T04:05:25.644396+00:00)

## What it is
CIRCL is Cloudflare's Go library of cryptographic primitives covering post-quantum algorithms (ML-KEM/Kyber, ML-DSA/Dilithium, SIKE/CSIDH), elliptic-curve cryptography (X25519, Ed448, BLS12-381), and protocols like HPKE and blind signatures. It is intended for experimental deployment and standardization work, with some packages not fully constant-time.

## Use cases
- add post-quantum key exchange to a Go application
- implement hybrid TLS with ML-KEM
- sign and verify with ML-DSA / Dilithium
- use HPKE for encrypted payloads in Go
- experiment with elliptic curves like FourQ and BLS12-381
- prototype blind signature schemes
- evaluate FIPS 203/204 algorithms before standard adoption

## When to choose
- you need post-quantum or advanced ECC primitives in Go not available in the standard library
- you are prototyping standards-track cryptography or PQ TLS experiments
- you want a maintained library from an experienced cryptography team

## When to avoid
- you need a fully audited, guaranteed constant-time library for production secrets - some packages leak timing
- you need API stability - the library warns its API may change
- you work outside the Go ecosystem

## Facets
- artifact type: library
- maturity: active
- function: cryptography, security, sdk
- domain: security, developer-tools, privacy
- platform: go, cross-platform
- tags: post-quantum, elliptic-curves, ml-kem, ml-dsa, kyber, dilithium, hpke, ed25519, pki, constant-time

## Member repositories
- cloudflare/circl (main) score 94

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:25.644396+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 2026-08-30T03:35:08.116817+00:00, confidence not recorded.
  - readme: https://github.com/cloudflare/circl (fetched 2026-08-28T04:05:25.644396+00:00, sha 50ea3069cea1)
  - homepage: http://blog.cloudflare.com/introducing-circl (fetched 2026-08-29T11:11:08.862059+00:00, sha 5ad98fc1a554)
  - site_page: https://blog.cloudflare.com/tag/developer-documentation (fetched 2026-08-29T11:11:08.864945+00:00, sha 12bb2ca0cd87)
  - site_page: https://www.cloudflare.com/about (fetched 2026-08-29T11:11:08.866918+00:00, sha 966c42a9a06f)
- Data as of 2026-08-30T08:39:29.467469+00:00.