THE SOFTWARE IS PROVIDED "AS IS" AND BRIAN SMITH AND THE AUTHORS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL BRIAN SMITH OR THE AUTHORS BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
ring is focused on the implementation, testing, and optimization of a core set of cryptographic operations exposed via an easy-to-use (and hard-to-misuse) API. ring exposes a Rust API and is written in a hybrid of Rust, C, and assembly language.
Particular attention is being paid to making it easy to build and integrate ring into applications and higher-level frameworks, and to ensuring that ring works optimally on small devices, and eventually microcontrollers, to support Internet of Things (IoT) applications.
ring is focused on general-purpose cryptography. WebPKI X.509 certificate validation is done in the webpki project, which is built on top of ring. Also, multiple groups are working on implementations of cryptographic protocols like TLS, SSH, and DNSSEC on top of ring.
ring is the successor of an earlier project called GFp. GFp implemented some elliptic curve cryptography over prime finite fields, also known as prime Galois fields and often denoted GF(p). When we implemented RSA, the name GFp did not make as much sense, since modular arithmetic over RSA public moduli is not GF(p) arithmetic but rather finite commutative ring arithmetic. Also note that ring started as a subset of BoringSSL, and “ring” is a substring of “BoringSSL”.
Most of the C and assembly language code in ring comes from BoringSSL, and BoringSSL is derived from OpenSSL. ring merges changes from BoringSSL regularly. Also, several changes that were developed for ring have already been merged into BoringSSL.
See the documentation at https://briansmith.org/rustdoc/ring/.
See BUILDING.md for instructions on how to build it. These instructions are especially important on Windows when not building from crates.io, as there are build prerequisites that need to be installed.
ring's benchmarks are in the crypto-bench project. Because there is lots of platform-specific code in ring, and because ring chooses dynamically at runtime which optimized implementation of each crypto primitive to use, it is very difficult to publish a useful single set of benchmarks; instead, you are highly encouraged to run the benchmarks yourselves on your target hardware.
The most important contributions are uses of ring. That is, we're very interested in seeing useful things built on top of ring, like implementations of TLS, SSH, the Noise Protocol, etc.
Of course, contributions to ring's code base are highly appreciated too. The ring project happily accepts pull requests without you needing to sign any formal license agreement. The portions of pull requests that modify existing files must be licensed under the same terms as the files being modified. New files in pull requests, including in particular all Rust code, must be licensed under the ISC-style license. Please state that you agree to license your contributions in the commit messages of commits in pull requests, e.g. by putting this at the bottom of your commit message:
I agree to license my contributions to each file under the terms given at the top of each file I changed.
If you want to work directly on ring and you don't have an idea for something to contribute already, see these curated lists of open issues:
- good-first-bug: Bugs that we think newcomers might find best to start with. Note that what makes a bug a good fit depends a lot on the developer's background and not just the hardness of the work.
- oxidation: Replacing C code with Rust code.
- rsa: The primary ring developer is less interested in RSA than ECC and other things, and it would be great to have somebody jump in and "own" the RSA work. ring has inherited the fastest open source RSA implementation (as far as we know) from BoringSSL/OpenSSL, and we've already done a lot of cleanup. But, there's a lot more work to do.
In addition, we're always interested in these kinds of contributions:
- Expanded benchmarks in the crypto-bench project.
- Additional testing code and additional test vectors.
- Static analysis and fuzzing in the continuous integration.
- Support for more platforms in the continuous integration (e.g. Android, iOS, ARM microcontrollers).
- Documentation improvements.
- More code simplification, especially eliminating dead code.
- Improving the code size, execution speed, and/or memory footprint.
- Fixing any bugs you may have found.
- Better IDE support for Windows (e.g. running the tests within the IDE) and macOS (e.g. Xcode project files).
Before submitting pull requests, make sure that the tests succeed both when
cargo test and
cargo test --features=rsa_signing. See
BUILDING.md for more info about the features flags that are
useful for people hacking on ring.
Versioning & Stability
Users of ring should always use the latest released version, and users should upgrade to the latest released version as soon as it is released. ring has a linear release model that favors users of the latest released version. We have never backported fixes to earlier releases and we don't maintain branches other than the master branch. Further, for some obscure technical reasons it's currently not possible to link two different versions of ring into the same program; for policy reasons we don't bother to try to work around that. Thus it is important that libraries using ring update to the latest version of ring ASAP, so that libraries that depend on their libraries can upgrade to the latest version of ring.
ring is tested on the latest Stable, Beta, and Nightly releases of Rust.
We do not spend effort on backward compatibility with older releases of
Rust; for example, when Rust 1.53 (Stable) is released, we don't care if
ring stops working with Rust 1.52 or earlier versions. Thus, we can
always use the latest stable features of the Rust language in ring.
So far we've never used unstable features of Rust except for the benchmarking
#[bench]), and we're hoping to remove even that Nightly
dependency. Sometimes things are broken with Nightly Rust. We prioritize
keeping things working on Stable; if things break on Beta and Nightly then
that breakage won't be considered urgent, though it will eventually get
resolved, one way or another.
We prefer to improve ring's API over keeping ring's API stable. We don't keep old APIs around for the sake of backward compatibility; we prefer to remove old APIs in the same change that adds new APIs. This makes it easier for people to contribute improvements. This means that sometimes upgrading to the newest version of ring will require some code changes. Over time the rate of change in the API will probably slow to the point where it will be stable in practice.
We don't have release notes. Instead, we try to clearly document each change in each commit. Read the the commit message, the tests, and the patch itself for each change. If anything is still unclear, let us know by submitting a pull request or by filing an issue in the issue tracker so that we can improve things.
This model of development is different than the model a lot of other open source libraries use. The idea behind our model is to encourage all users to work together to ensure that the latest version is good as it is being developed. In particular, because users know that correctness/security fixes (if any) aren't going to get backported, they have a strong incentive to help review pull requests before they are merged and/or review commits on the master branch after they've landed to ensure that code quality on the master branch stays high.
The more common model, where there are stable versions that have important security patches backported, lowers people's incentives to actively participate in mainline development. Maintaining stable APIs also discourages improving API design and internal code quality. Thus that model doesn't seem like a good fit for ring.
Every six months we have a meeting to revisit this policy. Email firstname.lastname@example.org if you want to attend the next meeting. Please don't file issues regarding this policy.
Please report bugs either as pull requests or as issues in the issue tracker. ring has a full disclosure vulnerability policy. Please do NOT attempt to report any security vulnerability in this code privately to anybody.
Online Automated Testing
Travis CI is used for Android, Linux, and macOS. Appveyor is used for Windows. The tests are run in debug and release configurations, for the current release of each Rust channel (Stable, Beta, Nightly), for each configuration listed in the table below. The C compilers listed are used for compiling the C portions.
|Linux||x86, x86_64||GCC 4.8, GCC 7, Clang 5||Build Status|
|32‑bit ARM, AAarch64||GCC (Ubuntu/Linaro 4.8.4-2ubuntu1~14.04.1), tested using
|Android||32‑bit ARM||Built using the Android SDK 24.4.1 and Android NDK 14, tested using the Android emulator.|
|Mac OS X||x64||Apple LLVM version 9.0.0 (clang-900.0.39.2) from Xcode 9.3|
|Windows||x86, x86_64||MSVC 2015 Update 3 (14.0)||Build Status|