npm package: @taichi-yi/jsotp
Description: Javascript One-Time Password module.
Author: lancegin
Latest version: 1.1.1

# jsotp

`jsotp` is a node module to generate and verify one-time passwords that were used to implement 2FA and MFA authentication method in web applications and other login-required systems.

The module was implement based on [RFC4226](https://tools.ietf.org/html/rfc4226) (HOTP: An HMAC-Based One-Time Password Algorithm) and [RFC6238](https://tools.ietf.org/html/rfc6238) (TOTP: Time-Based One-Time Password Algorithm)

### Example

![](http://wx4.sinaimg.cn/large/89243dfbgy1fh3bz5e8bkj20rs0go460.jpg)

### Feature

* Generate random base32 encoded string
* Generate a `otpauth url` with the b32 encoded string
* Create a HOTP object with verification
* Verify a HOTP token
* Create a TOTP object with verification
* Verify a TOTP token

### Installation

```shell
npm install jsotp
```

### Module

All modules support:

```javascript
const jsotp = require('jsotp');
```

### Usage

#### Time-based OTPs

```javascript
// import
const jsotp = require('jsotp');

// Create TOTP object
const totp = jsotp.TOTP('BASE32ENCODEDSECRET');
totp.now(); // => 432143
totp.prev(); // => 666666

// Verify for current time
totp.verify(432143); // => true

// Verify after 30s
totp.verify(432143); // => false
```

#### Counter-based OTPs

```javascript
// import
const jsotp = require('jsotp');

// Create HOTP object
const hotp = jsotp.HOTP('BASE32ENCODEDSECRET');
hotp.at(0); // => 432143
hotp.at(1); // => 231434
hotp.at(2132); // => 242432

// Verify with a counter
hotp.verify(242432, 2132); // => true
hotp.verify(242432, 2133); // => false
```

#### Generate random base32 encoded secret

```javascript
// import
const jsotp = require('jsotp');

// Generate
const b32_secret = jsotp.Base32.random_gen();
```

### Api

#### • [jsotp.Base32.random_gen(length)](https://github.com/LanceGin/jsotp/blob/master/src/base32.js#L32)

param: length
type: int
default: 16
return: String
desc: the length of random base32 encoded string.

#### • [jsotp.TOTP(secret)](https://github.com/LanceGin/jsotp/blob/master/src/jsotp.js#L48)

param: secret
type: string
return: TOTP
desc: generate TOTP instance.

#### • [jsotp.TOTP.now()](https://github.com/LanceGin/jsotp/blob/master/src/totp.js#L38)

return: String
desc: get the one-time password with previous time.

#### • [jsotp.TOTP.prev()](https://github.com/LanceGin/jsotp/blob/master/src/totp.js#L46)

return: String
desc: get the one-time password with current time.

#### • [jsotp.TOTP.verify(totp)](https://github.com/LanceGin/jsotp/blob/master/src/totp.js#L70)

param: totp
type: string
return: Boolean
desc: verify the totp code.

#### • [jsotp.TOTP.url_gen(issuer)](https://github.com/LanceGin/jsotp/blob/master/src/totp.js#L94)

param: issuer
type: string
return: string
desc: generate url with TOTP instance

#### • [jsotp.HOTP(secret)](https://github.com/LanceGin/jsotp/blob/master/src/jsotp.js#L47)

param: secret
type: string
return: HOTP
desc: generate HOTP instance.

#### • [jsotp.HOTP.at(counter)](https://github.com/LanceGin/jsotp/blob/master/src/hotp.js#L24)

param: counter
type: int
return: String
desc: generate one-time password with counter.

#### • [jsotp.HOTP.verify(hotp, count)](https://github.com/LanceGin/jsotp/blob/master/src/hotp.js#L50)

param: hotp
type: string
param: count
type: int
return: Boolean
desc: verify the hotp code.

#### • [jsotp.HOTP.url_gen(issuer)](https://github.com/LanceGin/jsotp/blob/master/src/hotp.js#L69)

param: issuer
type: string
return: string
desc: generate url with HOTP instance

### Contribute

* Clone repo and install dependencies

```shell
git clone git@github.com:LanceGin/jsotp.git
npm install
```

* Contribute the code in `src/`, and run command below to build the es6 code to es2015. That will create a local directory named `lib/`.

```shell
npm run build
```

* Unit test

```shell
npm test
```

### [中文文档](docs/README_zh.md)