# bigint-mod-arith 

Some extra functions to work with modular arithmetics using native JS (stage 3) implementation of BigInt. It can be used with Node.js (starting in version 10.4.0) and [Web Browsers supporting BigInt](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt#Browser_compatibility).

If you are looking for a cryptographically secure random generator and for probale primes (generation and testing), you may be interested in [bigint-secrets](https://github.com/juanelas/bigint-secrets)

_The operations supported on BigInts are not constant time. BigInt can be therefore **[unsuitable for use in cryptography](https://www.chosenplaintext.ca/articles/beginners-guide-constant-time-cryptography.html)**_

Many platforms provide native support for cryptography, such as [webcrypto](https://w3c.github.io/webcrypto/Overview.html) or [node crypto](https://nodejs.org/dist/latest/docs/api/crypto.html).

## Installation
bigint-mod-arith is distributed as both an ES6 and a CJS module.

The ES6 module is built for any [web browser supporting BigInt](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt#Browser_compatibility). The module only uses native javascript implementations and no polyfills had been applied.

The CJS module is built as a standard node module.

bigint-mod-arith can be imported to your project with `npm`:
```bash
npm install bigint-mod-arith
```

For web brosers, you can also [download the bundle from GitHub](https://raw.githubusercontent.com/juanelas/bigint-mod-arith/master/dist/bigint-mod-arith-latest.browser.mod.min.js) or just hotlink to it:
```html
<script type="module" src="https://raw.githubusercontent.com/juanelas/bigint-mod-arith/master/dist/bigint-mod-arith-latest.browser.mod.min.js"></script>
```

## Usage examples

```javascript
const modArith = require('bigint-mod-arith');

let a = BigInt(5); // more linter friendly
let b = 2n; // stage 3 short syntax for BigInt
let n = 19n;

console.log(modArith.modPow(a, b, n)); // prints 13

console.log(modArith.modInv(2n, 5n)); // prints 3

console.log(modArith.modInv(3n, 5n)); // prints 2
```

# bigint-mod-arith JS Doc

{{>main}}

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