CIRCL

CIRCL (Cloudflare Interoperable, Reusable Cryptographic Library) is a collection of cryptographic primitives written in Go. The goal of this library is to be used as a tool for experimental deployment of cryptographic algorithms targeting Post-Quantum (PQ) and Elliptic Curve Cryptography (ECC).

Security Disclaimer

🚨 This library is offered as-is, and without a guarantee. Therefore, it is expected that changes in the code, repository, and API occur in the future. We recommend to take caution before using this library in a production application since part of its content is experimental.

Installation

You can get it by typing:

go get -u github.com/cloudflare/circl

Versioning

Version numbers are Semvers. We release a minor version for new functionality, a major version for breaking API changes, and increment the patchlevel for bugfixes.

Implemented Primitives

Category	Algorithms	Description	Applications
PQ Key Exchange	SIDH	SIDH provide key exchange mechanisms using ephemeral keys.	Post-quantum key exchange in TLS
PQ Key Exchange	cSIDH	Isogeny based drop-in replacement for Diffie–Hellman	Post-Quantum Key exchange.
PQ KEM	SIKE	SIKE is a key encapsulation mechanism (KEM).	Post-quantum key exchange in TLS
Key Exchange	X25519, X448	RFC-7748 provides new key exchange mechanisms based on Montgomery elliptic curves.	TLS 1.3. Secure Shell.
Key Exchange	FourQ	One of the fastest elliptic curves at 128-bit security level.	Experimental for key agreement and digital signatures.
Key Exchange / Digital signatures	P-384	Our optimizations reduce the burden when moving from P-256 to P-384.	ECDSA and ECDH using Suite B at top secret level.
Digital Signatures	Ed25519, Ed448	RFC-8032 provides new signature schemes based on Edwards curves.	Digital certificates and authentication.
Key Encapsulation	P-256, P-384, P-521, X25519 and X448	Key encapsulation methods based on Diffie-Hellman.	HPKE
Hybrid Public-Key Encryption	Base, Auth, PSK, AuthPSK	HPKE is a combination of KEM and AEAD.	TLS
PQ KEM/PKE	Kyber	Lattice (M-LWE) based IND-CCA2 secure key encapsulation mechanism and IND-CPA secure public key encryption	Post-Quantum Key exchange
PQ Digital Signatures	Dilithium, Hybrid modes	Lattice (Module LWE) based signature scheme	Post-Quantum PKI

Work in Progress

Category	Algorithms	Description	Applications
Hashing to Elliptic Curve Groups	Several algorithms: Elligator2, Ristretto, SWU, Icart.	Protocols based on elliptic curves require hash functions that map bit strings to points on an elliptic curve.	VOPRF. OPAQUE. PAKE. Verifiable random functions.
Bilinear Pairings	Plans for moving BN256 to stronger pairing curves.	A bilineal pairing is a mathematical operation that enables the implementation of advanced cryptographic protocols, such as identity-based encryption (IBE), short digital signatures (BLS), and attribute-based encryption (ABE).	Geo Key Manager, Randomness Beacon, Ethereum and other blockchain applications.
PQ KEM	HRSS-SXY	Lattice (NTRU) based key encapsulation mechanism.	Key exchange for low-latency environments
PQ Digital Signatures	SPHINCS+	Stateless hash-based signature scheme	Post-Quantum PKI

Testing and Benchmarking

Library comes with number of make targets which can be used for testing and benchmarking:

• test performs testing of the binary.
• bench runs benchmarks.
• cover produces coverage.
• lint runs set of linters on the code base.

Contributing

To contribute, fork this repository and make your changes, and then make a Pull Request. A Pull Request requires approval of the admin team and a successful CI build.

How to Cite

To cite CIRCL, use one of the following formats and update with the date you accessed this project.

APA Style

Faz-Hernández, A. and Kwiatkowski, K. (2019). Introducing CIRCL: 
An Advanced Cryptographic Library. Cloudflare. Available at 
https://github.com/cloudflare/circl. Accessed Feb 2021.

Bibtex Source

@manual{circl,
  title        = {Introducing CIRCL: An Advanced Cryptographic Library},
  author       = {Armando Faz-Hern\'{a}ndez and Kris Kwiatkowski},
  organization = {Cloudflare},
  abstract     = {{CIRCL (Cloudflare Interoperable, Reusable Cryptographic Library) is
                   a collection of cryptographic primitives written in Go. The goal 
                   of this library is to be used as a tool for experimental 
                   deployment of cryptographic algorithms targeting Post-Quantum (PQ)
                   and Elliptic Curve Cryptography (ECC).}},
  note         = {Available at \url{https://github.com/cloudflare/circl}. Accessed Feb 2021},
  month        = jun,
  year         = {2019}
}

License

The project is licensed under the BSD-3-Clause License.