rsa/README.md

# [RustCrypto]: RSA

[![crates.io][crate-image]][crate-link]
[![Documentation][doc-image]][doc-link]
[![Build Status][build-image]][build-link]
[![dependency status][deps-image]][deps-link]
![MSRV][msrv-image]
[![Project Chat][chat-image]][chat-link]

A portable RSA implementation in pure Rust.

## Example

```rust
use rsa::{Pkcs1v15Encrypt, RsaPrivateKey, RsaPublicKey};

let mut rng = rand::thread_rng();
let bits = 2048;
let priv_key = RsaPrivateKey::new(&mut rng, bits).expect("failed to generate a key");
let pub_key = RsaPublicKey::from(&priv_key);

// Encrypt
let data = b"hello world";
let enc_data = pub_key.encrypt(&mut rng, Pkcs1v15Encrypt, &data[..]).expect("failed to encrypt");
assert_ne!(&data[..], &enc_data[..]);

// Decrypt
let dec_data = priv_key.decrypt(Pkcs1v15Encrypt, &enc_data).expect("failed to decrypt");
assert_eq!(&data[..], &dec_data[..]);
```

> **Note:** If you encounter unusually slow key generation time while using `RsaPrivateKey::new` you can try to compile in release mode or add the following to your `Cargo.toml`. Key generation is much faster when building with higher optimization levels, but this will increase the compile time a bit.
> ```toml
> [profile.debug]
> opt-level = 3
> ```
> If you don't want to turn on optimizations for all dependencies,
> you can only optimize the `num-bigint-dig` dependency. This should
> give most of the speedups.
> ```toml
> [profile.dev.package.num-bigint-dig]
> opt-level = 3
> ```

## Status

Currently at Phase 1 (v) 🚧

There will be three phases before `1.0` 🚢 can be released.

1. 🚧  Make it work
    - [x] Prime generation ✅
    - [x] Key generation ✅
    - [x] PKCS1v1.5: Encryption & Decryption ✅
    - [x] PKCS1v1.5: Sign & Verify ✅
    - [ ] PKCS1v1.5 (session key): Encryption & Decryption
    - [x] OAEP: Encryption & Decryption
    - [x] PSS: Sign & Verify
    - [x] Key import & export
2. 🚀 Make it fast
    - [x] Benchmarks ✅
    - [ ] compare to other implementations 🚧
    - [ ] optimize 🚧
3. 🔐 Make it secure
    - [ ] Fuzz testing
    - [ ] Security Audits

## Security Notes

This crate has received one [security audit by Include Security][audit], with
only one minor finding which has since been addressed.

See the [open security issues] on our issue tracker for other known problems.

Notably the implementation of [modular exponentiation is not constant time],
but timing variability is masked using random blinding, a commonly used
technique.

## Minimum Supported Rust Version (MSRV)

All crates in this repository support Rust 1.65 or higher.

In the future MSRV can be changed, but it will be done with a minor version bump.

## License

Licensed under either of

 * [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
 * [MIT license](http://opensource.org/licenses/MIT)

at your option.

### Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.

[//]: # (badges)

[crate-image]: https://buildstats.info/crate/rsa
[crate-link]: https://crates.io/crates/rsa
[doc-image]: https://docs.rs/rsa/badge.svg
[doc-link]: https://docs.rs/rsa
[build-image]: https://github.com/rustcrypto/RSA/workflows/CI/badge.svg
[build-link]: https://github.com/RustCrypto/RSA/actions?query=workflow%3ACI+branch%3Amaster
[msrv-image]: https://img.shields.io/badge/rustc-1.65+-blue.svg
[chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg
[chat-link]: https://rustcrypto.zulipchat.com/#narrow/stream/260047-RSA
[deps-image]: https://deps.rs/repo/github/RustCrypto/RSA/status.svg
[deps-link]: https://deps.rs/repo/github/RustCrypto/RSA

[//]: # (links)

[RustCrypto]: https://github.com/RustCrypto/
[audit]: https://www.opentech.fund/results/security-safety-audits/deltachat/
[open security issues]: https://github.com/RustCrypto/RSA/issues?q=is%3Aissue+is%3Aopen+label%3Asecurity
[modular exponentiation is not constant time]: https://github.com/RustCrypto/RSA/issues/19