Contributing new schemes to PQClean

Why contribute to PQClean

PQClean hopes to provide your scheme to people who want to integrate post-quantum cryptography into their own libraries and applications. But our extensive testing framework might also help you catch bugs in your implementation, that might have otherwise gone unnoticed. We run our builds on (emulated) ARMv7, ARMv8, x86 and amd64. Also, we apply static and dynamic analysis tools.

Adding your scheme

For this text, we will assume that you want to contribute a key encapsulation mechanism (KEM) to PQClean. For a signature scheme, these steps are equivalent, but the API is slightly different. See the section API below.

Fork our repository. You will be creating a pull request soon.
- Tip: Do not wait until you think you have gotten everything perfect, before you open the pull request. We set up things so Github and the CI environment will give you feedback and guidance on the steps to follow.
Create the following folder structure: crypto_kem/yourschemename/clean. We follow the SUPERCOP layout, so please create a separate folder under crypto_kem for each parameter set.

For now, we only accept pure, portable C code. Our coding conventions impose certain constraints on the C code -- C99 code, fixed sized integer types (e.g., uint64_t rather than unsigned long long), and more. See README.md for more information.

Create a META.yml file in crypto_kem/yourschemename following this template:

name: Name
type: <kem|signature>
claimed-nist-level: <N>
length-public-key: <N>
length-ciphertext: <N>
testvectors-sha256: sha256sum of output of testvectors
principal-submitter: Eve
auxiliary-submitters:
  - Alice
  - Bob
  - ...
implementations:
  - name: clean
    version: <some version indicator>

This file needs to be valid YAML.

Put your scheme's C source code into crypto_kem/yourschemename/clean.
1. Make sure all symbols are prefixed with PQCLEAN_YOURSCHEME_CLEAN_.
2. Include api.h into your scheme with the symbols specified in the section API.
Create Makefile and Makefile.Microsoft_nmake files to compile your scheme as static library.
- We suggest you copy these from crypto_kem/kyber768/clean and modify them to suit your scheme.
Add a LICENSE file to your implementation folder.
Commit everything and push it to your fork.
Open a pull request on our Github repository and process the feedback given to you by the CI environment. The pull request will also set up a checklist for you and us to follow. Feel free to ask us questions via the pull request.

API

These items should be available in your api.h file.

KEMs

Functions:

int PQCLEAN_YOURSCHEME_CLEAN_crypto_kem_keypair(unsigned char *pk, unsigned char *sk);
int PQCLEAN_YOURSCHEME_CLEAN_crypto_kem_enc(unsigned char *ct, unsigned char *ss, const unsigned char *pk);
int PQCLEAN_YOURSCHEME_CLEAN_crypto_kem_dec(unsigned char *ss, const unsigned char *ct, const unsigned char *sk);

#define macros:

CRYPTO_SECRETKEYBYTES
CRYPTO_PUBLICKEYBYTES
CRYPTO_CIPHERTEXTBYTES
CRYPTO_BYTES
CRYPTO_ALGNAME

Signature schemes

Functions:

int PQCLEAN_YOURSCHEME_CLEAN_crypto_sign_keypair(unsigned char *pk, unsigned char *sk);
int PQCLEAN_YOURSCHEME_CLEAN_crypto_sign(unsigned char *sm, unsigned long long *smlen, const unsigned char *msg, unsigned long long len, const unsigned char *sk);
int PQCLEAN_YOURSCHEME_CLEAN_crypto_sign_open(unsigned char *m, unsigned long long *mlen, const unsigned char *sm, unsigned long long smlen, const unsigned char *pk);

#define macros:

CRYPTO_SECRETKEYBYTES
CRYPTO_PUBLICKEYBYTES
CRYPTO_BYTES
CRYPTO_ALGNAME

Please make sure your api.h file does not include any other files.

Return codes

Your schemes should return 0 on success, or a negative value on failure. Notably, crypto_sign_open should return -1 if signature verification failed.

Contributing to the framework of PQClean

We also welcome contributions to the testing framework. Open an issue or pull request on Github and we will review your suggestion. In general, we are always looking to improve the experience of submitters of schemes and of people consuming the implementations collected by this project. Please do bear in mind the intentions of this project.

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