# CRYSTALS-KYBER JavaScript

<p align="center">
  <img src="./kyber.png"/>
</p>

**CRYSTALS-KYBER** is a post-quantum key exchange protocol.

This protocol is used to securely establish symmetric keys between two parties. 

This JavaScript implementation is intended for client-side web browser applications and server-side backends in Node.js frameworks.

Most of this code was translated from a Go implementation of Kyber which can be found [here](https://github.com/symbolicsoft/kyber-k2so).

Original code (written in C) can be found [here](https://github.com/pq-crystals/kyber).

Kyber comes in 512, 768, 1024 security strengths.

This code is the most up to date version based off the [NIST PQC Round 3 Submissions](https://csrc.nist.gov/projects/post-quantum-cryptography/round-3-submissions).

## Functionality

**KYBER** will securely distribute a 256 bit symmetric key between two parties. To safely transmit data over a channel using the key, an AEAD is advised (such as AES-256-GCM).

The exchange can be visualised below:

![](./diagram.svg)

## Usage
Using Node.js (v16.17.0) or React:
```bash
npm install crystals-kyber
```
Import the module at the top of your js file.
```js
const kyber = require('crystals-kyber');
```
To use in your code (768 can be replaced with 512 or 1024).
```js
// To generate a public and private key pair (pk, sk)
let pk_sk = kyber.KeyGen768();
let pk = pk_sk[0];
let sk = pk_sk[1];

// To generate a random 256 bit symmetric key (ss) and its encapsulation (c)
let c_ss = kyber.Encrypt768(pk);
let c = c_ss[0];
let ss1 = c_ss[1];

// To decapsulate and obtain the same symmetric key
let ss2 = kyber.Decrypt768(c,sk);

// Test function with KATs
kyber.Test768();
```
## Running Tests
Output from function `kyber.Test768()` that tests compatibility with the C implementation based on run cases in `PQCkemKAT_2400.rsp`.
```
Test run [ 0 ] success
Test run [ 1 ] success
Test run [ 2 ] success
Test run [ 3 ] success
Test run [ 4 ] success
Test run [ 5 ] success
          .
          .
          .
Test run [ 95 ] success
Test run [ 96 ] success
Test run [ 97 ] success
Test run [ 98 ] success
Test run [ 99 ] success
 
All test runs successful.

ss1 <Buffer cd c4 7d 83 2b 49 5d 82 3c 08 34 ea 12 f0 4a 8f 5c 4c d6 19 b1 79 85 71 d6 b2 a7 c9 3f ac cc d1>
ss2 <Buffer cd c4 7d 83 2b 49 5d 82 3c 08 34 ea 12 f0 4a 8f 5c 4c d6 19 b1 79 85 71 d6 b2 a7 c9 3f ac cc d1>
1
```

## Further Information
More details about CRYSTALS-KYBER, lattice-based cryptography and a real-life use of this algorithm can be
read here [Active Implementation of Post-Quantum End-to-End Encryption](https://eprint.iacr.org/2021/356.pdf) [20 Apr 2021].