The Community Cryptography Specification Project (C2SP) is a project that facilitates the maintenance of cryptography specifications using software development methodologies. In other words, C2SP applies the successful processes of open source software development and maintenance to specification documents.
- C2SP decisions are not based on consensus. Instead, each spec is developed by its maintainers, who are responsible for reviewing and accepting changes, just like open source projects. This enables rapid, focused, and opinionated development. Since C2SP produces specifications, not standards, technical disagreements can be ultimately be resolved by forking.
- C2SP specs are updateable, and follow semantic versioning. Most specifications are expected to start at v0.x.x while in “draft” stage, then stay at v1.x.x for as long as they maintain backwards compatibility, ideally forever. Drafts are expected to bump the minor version on breaking changes.
- C2SP documents are developed as Markdown files on GitHub, and can include ancillary files such as test vectors and non-production reference implementations.
A small team of stewards maintains the overall project, enforces the C2SP Code of Conduct, assigns new specifications to proposed maintainers, and may intervene in case of maintainer conflict or to replace lapsed maintainers, but they are otherwise not involved in the development of individual specs (in their steward capacity).
Versions are tracked as git tags of the form <spec-name>/vX.Y.Z like
age/v1.2.3.
Specifications should be linked using their c2sp.org short-links.
https://c2sp.org/<spec-name> and https://c2sp.org/<spec-name>@<version> are
supported. The former is equivalent to @latest and redirects to the latest
tagged version. To link to the main branch, use @main. GitHub URLs should not
be considered stable.
All C2SP specifications are licensed under CC BY 4.0. All code and data in this repository is licensed under the BSD 1-Clause License (LICENSE-BSD-1-CLAUSE).
Specifications
| c2sp.org/age | File encryption format |
| c2sp.org/age-plugin | The age plugin stdio protocol |
| c2sp.org/BLAKE3 | A fast cryptographic hash function (and PRF, MAC, KDF, and XOF) |
| c2sp.org/chacha20-poly1305-siv | Misuse-resistant, key-committing AEAD scheme |
| c2sp.org/chacha8rand | Fast cryptographic random number generator |
| c2sp.org/chunked-encryption | Authenticated, streaming, random-access encryption for large messages |
| c2sp.org/cocktail-dkg | Distributed Key Generation protocol for FROST |
| c2sp.org/det-keygen | Deterministic key pair generation from seed |
| c2sp.org/FLOE | Online and random access authenticated encryption |
| c2sp.org/https-bastion | Bastion (reverse proxy) protocol for exposing HTTPS services |
| c2sp.org/httpsig-pq | Post-quantum algorithms for HTTP Message Signatures |
| c2sp.org/jq255 | Prime order groups, key exchange, and signatures |
| c2sp.org/mtc-tlog | A profile of Merkle Tree Certificates (MTCs) that uses tiled transparency logs |
| c2sp.org/phc-strings | Password Hashing Competition string format |
| c2sp.org/sequencehash | TupleHash-like functionality for arbitrary underlying hash functions |
| c2sp.org/signed-note | Cleartext signed messages |
| c2sp.org/static-ct-api | Static asset-based Certificate Transparency logs |
| c2sp.org/tlog-checkpoint | Interoperable transparency log signed tree heads |
| c2sp.org/tlog-cosignature | Witness cosignatures for transparency log checkpoints |
| c2sp.org/tlog-mirror | HTTP protocol to mirror transparency logs |
| c2sp.org/tlog-policy | Encoding for transparency log proof cosigning policies |
| c2sp.org/tlog-proof | Offline-verifiable transparency log proofs (or "spicy signatures") |
| c2sp.org/tlog-tiles | Static asset-based transparency log |
| c2sp.org/tlog-witness | HTTP protocol to obtain transparency log witness cosignatures |
| c2sp.org/upki-revocation | CRLite X.509 revocation data based on Clubcards |
| c2sp.org/vrf-r255 | Simplified ristretto255-based ECVRF ciphersuite |
| c2sp.org/well-known-ssh-hosts | .well-known HTTPS address for SSH known_hosts |
| c2sp.org/XAES-256-GCM | Extended-nonce AEAD from NIST-approved components |
Associated projects §
The C2SP organization hosts three other testing-focused projects:
-
Wycheproof, a large library of tests for cryptographic libraries against known attacks.
-
CCTV, the Community Cryptography Test Vectors, a repository of reusable test vectors.
-
x509-limbo, a suite of tests for X.509 certificate path validation.