# drand-core: Rust implementation of drand

[![Documentation](https://img.shields.io/badge/docs-main-blue.svg)][Documentation]
![License](https://img.shields.io/crates/l/drand_core.svg)
[![crates.io](https://img.shields.io/crates/v/drand_core.svg)][Crates.io]

[Crates.io]: https://crates.io/crates/drand_core
[Documentation]: https://docs.rs/drand_core/

drand-core is a library to retrieve public randomness generated by drand beacons. It features an HTTP client, and verification method.

The format specification is at [drand.love/docs/specification](https://drand.love/docs/specification/). drand was designed in [Scalable Bias-Resistant Distributed Randomness](https://eprint.iacr.org/2016/1067.pdf).

The reference interroperable Go implementation is available at [drand/drand](https://github.com/drand/drand).

## Tables of Content

* [Features](#features)
* [What's next](#whats-next)
* [Installation](#installation)
* [Usage](#usage)
  * [Common remotes](#common-remotes)
* [Security Considerations](#security-considerations)
* [License](#license)

## Features

* Retrieve and verify drand randomness
* Built-in beacon time estimation
* Chain and unchained randomness
* Signatures verification on G1 and G2
* Interroperability with Go and JS implementation
* wasm32 compatible library

## What's next

* P2P randomness retrieval

## Installation

| Environment        | CLI Command                |
|:-------------------|:---------------------------|
| Cargo (Rust 1.74+) | `cargo install drand_core` |

The library is tested against the following targets: `x86_64-unknown-linux-gnu`, `armv7-unknown-linux-gnueabihf`, `aarch64-unknown-linux-gnu`, `wasm32-unknown-unknown`

## Usage

Retrieve the latest beacon from `https://drand.cloudflare.com`.

```rust
use drand_core::HttpClient;

// Create a new client.
let client: HttpClient = "https://drand.cloudflare.com".try_into().unwrap();

// Get the latest beacon. By default, it verifies its signature against the chain info, and correlates the returned round number with the chain genesis time.
let latest = client.latest()?;
```

Code examples are provided in [drand_core/examples](./examples). You can run them using `cargo run --examples <name>`.

### Common remotes

| ID                    | Remote                                                                                          | Timelock encryption |
| :---------------------|:------------------------------------------------------------------------------------------------|:--------------------|
| `quicknet-cloudflare` | `https://drand.cloudflare.com/52db9ba70e0cc0f6eaf7803dd07447a1f5477735fd3f661792ba94600c84e971` | Yes                 |
| `quicknet-pl`         | `https://api.drand.sh/52db9ba70e0cc0f6eaf7803dd07447a1f5477735fd3f661792ba94600c84e971`         | Yes                 |
| `mainnet-cloudflare`  | `https://drand.cloudflare.com`                                                                  | No                  |
| `mainnet-pl`          | `https://api.drand.sh`                                                                          | No                  |

`drand_core` does not come with a default remote beacon. You should decide whichever suit your needs.

More beacon origins are available on [drand website](https://drand.love/developer/).

## Security Considerations

This library has not been audited. Please use at your sole discretion.

## License

This project is under the MIT license.

### Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you shall be MIT licensed as above, without any additional terms or conditions.