# OnlyOTP - An OTP generation, storage, and validation solution

![OnlyOTP Logo](https://raw.githubusercontent.com/OnlyOTP/OnlyOtpAssets/master/images/facebook_profile_image.png align="left")

## 1\. Install Nuget Package.

Install Nuget Package [https://www.nuget.org/packages/OnlyOTP](https://www.nuget.org/packages/OnlyOTP)

## 2\. Generate OTP

```CSharp
var otpProvider = new Otp();
//Generates 6 digit OTP by default
var otp = otpProvider.GenerateOtp();
```

## Advanced Options

## Generate OTP with specified length

```CSharp
var otpWithSpecifiedLength = otpProvider.GenerateOtp(new OtpOptions { Length = 10 });
```

## Generate OTP and Store In-Memory

### Install InMemory OTP Storage Nuget

Install additional Nuget Package [https://www.nuget.org/packages/OnlyOtp.Storage.InMemory](https://www.nuget.org/packages/OnlyOtp.Storage.InMemory)

### Instantiate `Otp` with `InMemoryOtpStorage`

```CSharp
public void SomeMethod()
{
    // Pass InMemoryOtpStorage to Otp Provider.
    var otpProvider = new Otp(new InMemoryOtpStorage());

    // Returns OTP and OTP Verification Token
    // Save this token to retreive generated OTP later

    (string myOtp, string myToken) = otpProvider.GenerateAndStoreOtp();
}
public void SomeOtherMethod(string otpEnteredByUser)
{
    // Match the stored OTP with OTP entered by user
    var isMatched = otpProvider.IsOtpMached(otpEnteredByUser, myToken);
}
```

## Generate OTP and Store it in SQL Server

### Install InMemory OTP Storage Nuget

Install additional Nuget Package [https://www.nuget.org/packages/OnlyOtp.Storage.SqlServer](https://www.nuget.org/packages/OnlyOtp.Storage.SqlServer)

### Create table and schema

`SqlServerOtpStorage` uses an `Sql Server` to store OTPs. Use this script to generate necessary table and schema.

```sql
GO
CREATE SCHEMA [OnlyOtp]
GO
CREATE TABLE [OnlyOtp].[Otp](
	[Id] [nvarchar](100) NOT NULL,
	[Value] [nvarchar](100) NOT NULL,
 CONSTRAINT [PK_Otp] PRIMARY KEY CLUSTERED 
(
	[Id] ASC
)) ON [PRIMARY]
GO
```

### Create `DbContext`

#### In an `ASP.NET Core` application

If you're using `ASP.NET Core`, you can use `Dependency Injection` to set-up `DbContext` used by `OnlyOtp`.

```csharp
public void ConfigureServices(IServiceCollection services)
{
    ...
    services.AddDbContext<OnlyOtpContext>(options =>
    {        
        options.UseSqlServer(@"Data Source=DATABASE_SERVER_NAME;Initial Catalog=DATABASE_NAME;Integrated Security=True;");
    });
    ...
}
```

And in `Controller` or any other class, inject this `DbContext`:

```csharp
public class HelloController : Controller
{
    private readonly OnlyOtpContext _onlyOtpContext;

    public HelloController(OnlyOtpContext onlyOtpContext)
    {
        _onlyOtpContext = onlyOtpContext;
    }
    
}
```

#### In any other application

You can instantiate the `DbContext` manually.

```csharp
var options = new DbContextOptionsBuilder<OnlyOtpContext>()
                .UseSqlServer(@"Data Source=DATABASE_SERVER_NAME;Initial Catalog=DATABASE_NAME;Integrated Security=True;")
                .Options;
var dbContext = new OnlyOtpContext(options);
```

### Use `Otp` with `SqlServerOtpStorage`

```csharp
public void SomeMethod()
{
    // Pass SqlServerOtpStorage to Otp Provider.
    var otpProvider = new Otp(new SqlServerOtpStorage(_onlyOtpContext));
    // Get OTP token and generated OTP
    (string otp, string token) = otpProvider.GenerateAndStoreOtp();
    //Save this token to retreive generated OTP later
    ...
}
public void SomeOtherActionMethod(string otpEnteredByUser)
{
    ...
    // Match the stored OTP with OTP entered by user
    bool isOtpMatched = otpProvider.IsOtpMached(otpEnteredByUser, token);
    ...
}
```