CasSystem.Client 2.0.0

.NET CAS Client

A .NET library for seamless integration with One System CAS (Central Authentication Service) SSO servers. Targets .NET 8 and works with ASP.NET Core 8.

Features

• 🔐 Secure SSO Authentication — JWT token-based authentication
• 🛡️ HMAC Signature Validation — Request signing with SHA-256
• 👥 Role-Based Access Control — ASP.NET Core middleware for role protection
• ⚡ Async/Await — Fully asynchronous API
• 💉 Dependency Injection — Built-in service registration extensions
• 🔄 Thread-Safe Caching — ConcurrentDictionary token cache

Requirements

• .NET 8 SDK (the package targets net8.0).
• An ASP.NET Core (web) host — the package references the Microsoft.AspNetCore.App shared framework for HttpContext, IServiceCollection, and the middleware.

Installation

NuGet

dotnet add package CasSystem.Client

Package Manager

Install-Package CasSystem.Client

How it works

1. Browser SSO — send the user to GetLoginUrl(), which builds GET {ServerUrl}/sso/login?client_id={ClientId}. The One System CAS server authenticates the user and 302-redirects the browser back to the registered callback_url with ?token={JWT} appended.
2. Server-to-server validation — call ValidateTokenAsync(token), which POSTs to {ServerUrl}/api/validate-token with { token, client_id, client_secret }. On success the server returns 200 { valid: true, user: { id, username, email }, expires_at }. The token is single-use — validate it exactly once, then create your own session.
3. Service-to-service issuance — GenerateSSOTokenAsync(username) POSTs to {ServerUrl}/api/sso/token with { client_id, client_secret, username } to mint a token for a user (the caller must be IP-whitelisted on the CAS server).

Quick Start

1. Configure in Program.cs

using CasSystem.Client;

var builder = WebApplication.CreateBuilder(args);

// Register CAS client
builder.Services.AddCasClient(new CasConfig
{
    ServerUrl = "https://your-cas-server.com",
    ClientId = "your_client_id",
    ClientSecret = "your_client_secret",
    CallbackUrl = "https://your-app.com/cas/callback",
});

builder.Services.AddSession();

var app = builder.Build();

app.UseSession();
app.UseMiddleware<CasAuthMiddleware>();

app.MapGet("/dashboard", (HttpContext ctx) =>
{
    var user = ctx.Items["cas_user"] as Dictionary<string, object>;
    return Results.Json(new { user });
});

app.Run();

2. Manual Authentication

using CasSystem.Client;

var config = new CasConfig
{
    ServerUrl = "https://your-cas-server.com",
    ClientId = "your_client_id",
    ClientSecret = "your_client_secret",
};
var cas = new CasClient(config);

// Generate login URL
var loginUrl = cas.GetLoginUrl("https://your-app.com/dashboard");

// Validate token
var user = await cas.ValidateTokenAsync(token);
if (user != null)
{
    var username = user["username"].ToString();
}

// Role checks
bool isAdmin = CasClient.UserHasRole(user, "admin");

// Logout
await cas.LogoutAsync(token);

3. Controller Usage

[ApiController]
[Route("api/[controller]")]
public class DashboardController : ControllerBase
{
    private readonly CasClient _cas;
    public DashboardController(CasClient cas) => _cas = cas;

    [HttpGet]
    public IActionResult Index()
    {
        var user = HttpContext.Items["cas_user"] as Dictionary<string, object>;
        if (user == null) return Unauthorized();
        return Ok(new { user });
    }
}

API Reference

License

MIT