Aegis - Robust and Flexible .NET Licensing Solution

Aegis is a comprehensive and versatile licensing library for .NET applications, empowering developers to implement various licensing models with ease. It offers strong security features, offline validation, and seamless integration with your existing applications.

Features

• Diverse Licensing Models:
  • Standard License: A basic license model for single-user applications.
  • Trial License: A time-limited license for evaluation purposes, with a defined trial period.
  • Node-Locked License: Licenses tied to specific hardware, preventing unauthorized usage on different machines.
  • Subscription License: Licenses valid for a specific duration, suitable for subscription-based services.
  • Floating License: Licenses managed on a server, allowing concurrent usage by a limited number of users within an organization.
  • Concurrent License: Licenses that allow a maximum number of simultaneous users, ideal for applications with shared access.
• Strong Security: Utilizes RSA encryption, digital signatures, and checksum verification to protect your licenses from tampering and unauthorized modifications.
• License Validation: Offers both online and offline license validation modes, ensuring flexibility even in scenarios without internet connectivity.
• Custom Validation Rules: Define and apply custom validation rules using IValidationRule and IValidationRuleGroup for tailored license requirements.
• Easy Integration: Provides a simple and intuitive API for generating, saving, loading, validating, and managing licenses within your .NET applications.
• Ease of Use: Provides a fluent API for building and managing licenses, simplifying integration into existing projects.
• Built-in Exceptions: Includes a set of exceptions for common licensing scenarios, simplifying error handling.

Aegis.Server - Backend for Floating and Concurrent Licenses

Aegis.Server is a lightweight backend service designed to handle floating and concurrent license management. It provides a foundation for building your own licensing server, offering functionalities like:

• License Generation and Validation: Generate, validate, activate, and revoke licenses securely.
• User Authentication: Securely register and authenticate users for accessing license-related operations.
• Heartbeat Monitoring: Track active concurrent license usage and automatically disconnect idle users.

You can integrate Aegis.Server into your preferred web framework or create a custom implementation based on your specific needs. Aegis.Server provides the core logic for license management, while allowing you to choose how you want to expose the functionality.

Aegis.Server.AspNetCore

A sample implementation of Aegis.Server using ASP.NET Core is available in the Aegis.Server.AspNetCore project. This implementation showcases how to integrate Aegis.Server into an ASP.NET Core application, providing ready-to-use controllers and middlewares for:

• RESTful API Endpoints: Access license management functionalities through a well-defined API.
• Authentication and Authorization: Secure access to API endpoints using JWT and API keys.
• Rate Limiting: Control the rate of requests to the server.
• Swagger Documentation: Explore the API endpoints using the interactive Swagger UI.

The Aegis.Server.AspNetCore project can be used as a starting point for building your own licensing server, or you can adapt the provided code to your specific needs.

Getting Started

Aegis NuGet Package

1. Install the Aegis NuGet package:

   Install-Package Aegis
   

2. Generate Licensing Secrets:

   // Replace "your-secret-key" and "C:\Path\To\signature.bin" with your desired secret key and save path.
   var signature = LicenseUtils.GenerateLicensingSecrets("your-secret-key", @"C:\Path\To\signature.bin", "your-server-api-key"); 

   This will generate a new RSA key pair and an encryption key. The public key, private key, and encryption key are encrypted with AES using your provided secret key and saved to the specified file path (signature.bin in this example).

3. Load Licensing Secrets:

   // Load the secret keys from the signature file
   var signature = LicenseUtils.LoadLicensingSecrets("your-secret-key", @"C:\Path\To\signature.bin");

   Use the same secret key to decrypt and load the licensing secrets from the file you created in step 2.

   Alternatively, you can:

   • Load directly from the configuration section:

   var signature = LicenseUtils.LoadLicensingSecrets(config.GetSection("LicensingSecrets"))

   • Add the keys to your User Secrets and they will be retrieved automatically.

4. Generate and Save a License (Examples for each license type):

   Standard License:

   using Aegis;
   
   var license = LicenseGenerator.GenerateStandardLicense("John Doe")
       .WithLicenseKey("SD2D-35G9-1502-X3DG-16VI-ELN2")
       .WithIssuer("Aegis Software")
       .WithFeature("Feature1", true)
       .WithFeature("Feature2", false)
       .WithExpiryDate(DateTime.UtcNow.AddDays(30))
       .SaveLicense(@"C:\Path\To\license.bin"); 

   Trial License:

   var license = LicenseGenerator.GenerateTrialLicense(TimeSpan.FromDays(14))
       .WithIssuer("Aegis Software")
       .WithFeature("AllFeatures", true) 
       .SaveLicense(@"C:\Path\To\trial_license.bin");

   Node-Locked License:

   var license = LicenseGenerator.GenerateNodeLockedLicense(HardwareUtils.GetHardwareId()) 
       .WithIssuer("Aegis Software")
       .WithExpiryDate(DateTime.UtcNow.AddYears(1))
       .SaveLicense(@"C:\Path\To\nodelocked_license.bin");

   Subscription License:

   var license = LicenseGenerator.GenerateSubscriptionLicense("Jane Smith", TimeSpan.FromDays(365))
       .WithIssuer("Aegis Software")
       .WithFeature("PremiumFeatures", true) 
       .SaveLicense(@"C:\Path\To\subscription_license.bin");

   Floating License:

   var license = LicenseGenerator.GenerateFloatingLicense("Acme Corp", 20) // 20 concurrent users allowed
       .WithIssuer("Aegis Software")
       .SaveLicense(@"C:\Path\To\floating_license.bin");

   Concurrent License:

   var license = LicenseGenerator.GenerateConcurrentLicense("Tech Solutions", 5) // 5 concurrent users allowed
       .WithIssuer("Aegis Software")
       .WithExpiryDate(DateTime.UtcNow.AddYears(1))
       .SaveLicense(@"C:\Path\To\concurrent_license.bin");

5. Load and Validate a License:

   try
   {
       var loadedLicense = await LicenseManager.LoadLicenseAsync(@"C:\Path\To\license.bin"); 
   
       // License loaded successfully, you can access its properties:
       Console.WriteLine("License Type: " + loadedLicense.Type);
       Console.WriteLine("Expiration Date: " + loadedLicense.ExpirationDate);
       // ...
   }
   catch (LicenseValidationException ex)
   {
       // Handle license validation errors (e.g., expired, invalid signature, etc.)
       Console.WriteLine("License Validation Error: " + ex.Message);
   }
   catch (Exception ex)
   {
       // Handle other errors (e.g., file not found, invalid format, etc.)
       Console.WriteLine("Error Loading License: " + ex.Message);
   } 

6. Check Feature Status:

   if (LicenseManager.IsFeatureEnabled("Feature1"))
   {
       // Allow access to Feature1
   }
   else
   {
       // Feature1 is not enabled, handle accordingly (e.g., disable UI elements, show a message)
   }
   
   // Or throw an exception if the feature is not allowed:
   LicenseManager.ThrowIfNotAllowed("Feature1"); 

Aegis.Server NuGet Package

1. Install the Aegis.Server NuGet package:

   Install-Package Aegis.Server
   

2. Integrate Aegis.Server into an ASP.NET Core application:

   // In your Startup.cs file:
   services.AddAegisServer();

3. Inherit your DbContext from AegisDbContext class:

   using Aegis.Server.Data;
   
   public class ApplicationDbContext(DbContextOptions<AegisDbContext> options) : AegisDbContext(options)
   {
       // ...
   }

4. Inject LicenseService in your Controller:

   using Aegis.Server.Services;
   
   public class LicensesController(LicenseService licenseService)
   {
       // ...
   }

Aegis.Server.AspNetCore Sample Implementation

1. Clone the Aegis repository and acquire Aegis.Server.AspNetCore from Samples directory:

   git clone https://github.com/LSXPrime/Aegis.git
   

2. Configure the database connection:

   • Open the appsettings.json file in the Aegis.Server.AspNetCore project.
   • Modify the DefaultConnection connection string to point to your SQLite database file. For example:

     "ConnectionStrings": {
       "DefaultConnection": "Data Source=C:\\Path\\To\\Your\\Database\\Aegis.db"
     }

3. Set the JWT settings:

   • In appsettings.json, configure the JwtSettings section with your secret key, salt, and token expiration settings:

     "JwtSettings": {
       "Secret": "your_jwt_secret_key",
       "Salt": "your_password_salt",
       "AccessTokenExpirationInDays": 1,
       "RefreshTokenExpirationInDays": 7
     }

   • Security Considerations: Use strong and unique values for your JWT secret key and password salt. Keep them confidential and do not expose them in client-side code.

4. Build and run the server:

   dotnet build
   dotnet run --project Aegis.Server.AspNetCore
   

5. Deployment:

   • You can deploy Aegis.Server to various environments, such as:
     • Azure App Service: Create an App Service in Azure and deploy your application.
     • Docker Container: Create a Docker image of your application and run it in a containerized environment.
     • Self-Hosted: Deploy your application to a server that you manage.

Concurrent and Floating License Activation

1. Activate a license from your client application:

   LicenseManager.SetServerBaseEndpoint("https://your-aegis-server-url");
   await LicenseManager.LoadLicenseAsync("path\to\license.bin", ValidationMode.Online); 

   Replace "https://your-aegis-server-url" with the actual URL of your Aegis.Server.AspNetCore deployment. The LoadLicenseAsync function will now perform online validation against the server.

2. Heartbeat Handling: For concurrent licenses, Aegis.Server automatically handles heartbeat requests sent from client applications. The client library should periodically send heartbeat requests to the server to maintain an active connection. You can configure the heartbeat interval using the LicenseManager.SetHeartbeatInterval() method.

3. Idle User Disconnection: Aegis.Server monitors heartbeats and will automatically disconnect users if a heartbeat is not received within a specified timeout period.

Custom Validation Rules

Aegis allows you to implement custom validation rules to enforce specific licensing requirements beyond the built-in validation logic. This provides greater flexibility and control over your licensing system.

1. Implementing a Custom Rule

   To create a custom validation rule, implement the IValidationRule interface:

   using Aegis.Interfaces;
   using Aegis.Models;
   using Aegis.Models.Utils;
   
   public class MyCustomRule : IValidationRule
   {
       public LicenseValidationResult<T> Validate<T>(T license, Dictionary<string, string?>? parameters) where T : BaseLicense
       {
           // Your custom validation logic here.
           // Access license properties, parameters, external resources, etc.
   
           if (/* Validation succeeds */)
           {
               return new LicenseValidationResult<T>(true, license);
           }
           else
           {
               // Provide an appropriate exception for validation failures.
               return new LicenseValidationResult<T>(false, null, new LicenseValidationException("Custom validation failed.")); 
           }
       }
   }

2. Registering the Rule

   Once you have implemented your custom rule, register it with the LicenseValidator:

   LicenseValidator.AddValidationRule(new MyCustomRule());

3. Example: Advanced Hardware Validation for Node-Locked Licenses

   This example demonstrates a more robust hardware validation for node-locked licenses, considering multiple hardware factors.

   using Aegis.Interfaces;
   using Aegis.Models;
   using Aegis.Models.Utils;
   using Aegis.Utilities;
   
   public class AdvancedHardwareRule : IValidationRule
   {
       public LicenseValidationResult<T> Validate<T>(T license, Dictionary<string, string?>? parameters) where T : BaseLicense
       {
           if (license is not NodeLockedLicense nodeLockedLicense)
               return new LicenseValidationResult<T>(true, license);
   
           // Implement your logic to combine and validate multiple hardware factors
           // You can use HardwareUtils.GetHardwareId() as a starting point and add
           // more specific checks for CPU ID, motherboard serial number, etc.
           string combinedHardwareId = GenerateCombinedHardwareId();
   
           if (combinedHardwareId != nodeLockedLicense.HardwareId)
           {
               return new LicenseValidationResult<T>(false, null, new HardwareMismatchException("Hardware mismatch detected."));
           }
   
           return new LicenseValidationResult<T>(true, license);
       }
   
       // Replace with your actual implementation to generate a combined hardware ID.
       private string GenerateCombinedHardwareId()
       {
           // ... your logic to combine multiple hardware factors ...
           return ""; // Replace with the generated combined ID
       }
   }

   Usage:

   LicenseValidator.AddValidationRule(new AdvancedHardwareRule());
   
   // ... during license loading ...
   var license = await LicenseManager.LoadLicenseAsync("license.bin"); 

   This example showcases how you can create a custom rule to enhance the security of your node-locked licenses by validating against multiple hardware identifiers.

   You can adapt this example and implement your own logic for combining and validating different hardware factors to suit your specific needs. Remember to provide clear documentation and error messages within your custom rules to make them easy to understand and maintain.

Custom Hardware Identification

By default, Aegis uses a DefaultHardwareIdentifier that combines Machine Name, User Name, OS Version, and MAC Address. To implement a custom hardware identifier:

1. Create a class that implements IHardwareIdentifier:

   using Aegis.Interfaces;
   
   public class MyCustomHardwareIdentifier : IHardwareIdentifier
   {
       public string GetHardwareIdentifier()
       {
           // Your custom logic to retrieve the hardware identifier.
           // Example: CPU ID, Motherboard serial number, etc.
           return "..."; 
       }
   
       public bool ValidateHardwareIdentifier(string hardwareIdentifier)
       {
           // Your custom logic to validate the hardware identifier.
           return GetHardwareIdentifier() == hardwareIdentifier;
       }
   }

2. Set the custom identifier:

   LicenseManager.SetHardwareIdentifier(new MyCustomHardwareIdentifier());

Custom Serialization

Aegis uses a JsonLicenseSerializer by default. To implement a custom serializer:

1. Create a class that implements ILicenseSerializer:

   using Aegis.Interfaces;
   using Aegis.Models;
   
   public class MyCustomSerializer : ILicenseSerializer
   {
       public string Serialize(BaseLicense license)
       {
           // Your custom serialization logic.
           // Example: XML serialization, binary serialization, etc.
           return "...";
       }
   
       public BaseLicense? Deserialize(string data)
       {
           // Your custom deserialization logic.
           return ...;
       }
   }

2. Set the custom serializer:

   LicenseManager.SetSerializer(new MyCustomSerializer());

Disabling Built-in Validation

You can disable Aegis's built-in validation logic if you want to rely solely on your custom validation rules or have a different validation process.

LicenseManager.SetBuiltInValidation(false); 

This will prevent LicenseManager from performing its default validation checks for license type, expiry date, and other built-in criteria. You will be responsible for implementing all necessary validation logic in your custom rules or through other means.

Architecture

Aegis Licensing System Architecture:

The Aegis licensing system comprises two main components: the Aegis client library (integrated into your .NET application) and the Aegis.Server backend service.

Client-Side:

• License Generation: Licenses are generated using the Aegis library, typically during the development or deployment process.
• License Storage: The generated license file is stored securely on the client machine (consider best practices for protecting this file).
• License Loading: The client application loads the license file using LicenseManager.LoadLicenseAsync().
• Validation:
  • Offline Validation: The license is validated locally using cryptographic signatures, checksums, and any registered custom validation rules.
  • Online Validation: For floating and concurrent licenses, the client library connects to the Aegis.Server.AspNetCore to validate the license and manage activations.
• Feature Access: The application checks for enabled features using LicenseManager.IsFeatureEnabled().
• Heartbeat (Concurrent Licenses): For concurrent licenses, the client library periodically sends heartbeat requests to the Aegis.Server.AspNetCore to maintain an active connection.

Server-Side:

• License Management: The Aegis.Server backend service manages licenses and activations.

• Heartbeat Monitor: A background service monitors heartbeat requests from clients and automatically disconnects inactive concurrent users.

• ASP.NET Core Sample Implementation: A sample ASP.NET Core application is available in the Aegis.Server.AspNetCore project and it offers.

  • API Endpoints: Aegis.Server.AspNetCore exposes RESTful API endpoints for license validation, activation, revocation, user authentication, and heartbeat monitoring.
  • Database: A SQL database is used to store license information, user data, activations, and other relevant data.
  • Authentication: Aegis.Server.AspNetCore uses JWT (JSON Web Tokens) for user authentication and authorization.
  • ApplicationDbContext: Aegis.Server.AspNetCore uses the ApplicationDbContext that inherits from AegisDbContext to store license information, user data, activations, and other relevant data.

Interaction:

• Client applications communicate with the Aegis.Server.AspNetCore using its API endpoints.
• For floating and concurrent licenses, the server tracks the number of active users and enforces license limits.
• The heartbeat mechanism ensures that the server has an up-to-date view of active concurrent users.

Troubleshooting

• License Validation Errors:

  • Ensure the license file is not corrupted or tampered with.
  • Check the system clock on the client machine to ensure it is accurate.
  • Verify the license key and any validation parameters (e.g., hardware ID, username) are correct.
  • If using online validation, ensure the server is reachable and the API key is configured correctly.

• Server Errors:

  • Check the server logs for any error messages.
  • Ensure the database connection string and JWT settings are configured correctly in the appsettings.json file.

• Concurrent License Issues:

  • If users are being disconnected unexpectedly, check the heartbeat interval and timeout settings on both the client and server.
  • Ensure that the server can handle the expected number of concurrent connections.

Contributing

Contributions to Aegis are welcome!

Guidelines:

1. Fork the repository on GitHub.
2. Create a new branch for your feature or bug fix.
3. Make your changes and ensure they follow the project's coding style.
4. Write tests to cover your changes.
5. Submit a pull request to the main repository.

License

This project is licensed under the MIT License - see the LICENSE file for details.