# Kotlin OTP

This library provides various [One-Time Password](https://en.wikipedia.org/wiki/One-time_password)
implementations in Kotlin Multiplatform.

## Features

* [HTOP](https://en.wikipedia.org/wiki/HMAC-based_one-time_password)
* [TOTP](https://en.wikipedia.org/wiki/Time-based_one-time_password)
* Multiplatform support
    * JVM
    * JavaScript
    * Native (Linux)

## Installation

Add the following to your `build.gradle.kts`.

```kotlin
repositories {
    maven("https://git.infendro.com/api/packages/Infendro/maven")
}

dependencies {
    implementation("com.infendro:otp:1.1.1")
}
```

## Usage

```kotlin
import com.infendro.hash.SHA1
import com.infendro.otp.SecretGenerator
import com.infendro.otp.TOTP
import kotlin.time.Clock.System.now
import kotlin.time.Duration.Companion.seconds

fun main() {
    // create a TOTP instance using SHA1, a length of 6, and a period of 30 seconds
    val totp = TOTP(
        function = SHA1,
        length = 6,
        period = 30.seconds,
    )

    // generate a secret using SHA1
    val secret = SecretGenerator.generate(SHA1)

    // generate an OTP
    val otp = totp.generate(secret, now())

    // verify an OTP
    totp.verify(secret, now(), otp)
}
```