> For the complete documentation index, see [llms.txt](https://developers.portos.sk/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers.portos.sk/authentication/authentication-schemes/hmac-authentication.md).

# HMAC Authentication

We have developed example projects that illustrate the implementation of HMAC authentication for communication with the PORTOS API.

## PHP

The source project and examples can be found in [ninedigit/nws4-php](https://github.com/ninedigit/nws4-php) GitHub project.

{% embed url="<https://github.com/ninedigit/nws4-php>" %}
The NWS4 implementation in PHP
{% endembed %}

## .NET C\#

The example project for C# can be found in [ninedigit/AspNetCore.Identity.NWS4.Examples](https://github.com/ninedigit/AspNetCore.Identity.NWS4.Examples) GitHub project.

{% embed url="<https://github.com/ninedigit/AspNetCore.Identity.NWS4.Examples>" %}
The NWS4 examples in C#
{% endembed %}

Examples are using the `NineDigit.NWS4` library, which can be found as NuGet package at [nuget.org](https://www.nuget.org/packages/NineDigit.NWS4).

{% embed url="<https://www.nuget.org/packages/NineDigit.NWS4>" %}
The NWS4 C# NuGet library&#x20;
{% endembed %}