System.Net.Security.IdentityValidator Class

Represents a class that validates the identity of a remote client during an authentication process.

Overview

The IdentityValidator class is part of the System.Net.Security namespace and is used to define custom logic for validating the identity of a remote client. This is particularly useful in scenarios where standard identity validation mechanisms are insufficient or when specific security policies need to be enforced.

This class allows developers to implement their own validation algorithms, such as checking against a list of approved identities, validating specific attributes of the identity, or performing contextual checks based on the connection or application state.

Syntax


public abstract class IdentityValidator

This is an abstract class and cannot be instantiated directly. You must derive from this class to implement your custom identity validation logic.

Requirements

Assembly	DLL
System.Net.Security.dll

Namespace
System.Net.Security

Remarks

When implementing a derived class, you will typically override the Validate method. This method receives the identity of the remote client and is responsible for determining if the identity is valid.

The IdentityValidator can be used in conjunction with classes like SslStream or other authentication protocols that require identity verification.

Members

Methods

Name	Description
Validate(IIdentity)	Abstract method to be implemented by derived classes. Validates the provided `IIdentity` object.

Example

The following example demonstrates how to create a simple custom IdentityValidator that only allows a specific username to connect.


using System;
using System.Net.Security;
using System.Security.Principal;

// Define a custom identity validator
public class SpecificUserValidator : IdentityValidator
{
    private readonly string _allowedUserName;

    public SpecificUserValidator(string allowedUserName)
    {
        _allowedUserName = allowedUserName ?? throw new ArgumentNullException(nameof(allowedUserName));
    }

    // Override the abstract Validate method
    public override void Validate(IIdentity identity)
    {
        if (identity == null)
        {
            throw new ArgumentNullException(nameof(identity));
        }

        Console.WriteLine($"Validating identity: {identity.Name} (Authentication Type: {identity.AuthenticationType})");

        // Check if the authenticated user's name matches the allowed user name
        if (!identity.IsAuthenticated || !identity.Name.Equals(_allowedUserName, StringComparison.OrdinalIgnoreCase))
        {
            throw new IdentityNotValidException($"Identity '{identity.Name}' is not authorized.");
        }

        Console.WriteLine($"Identity '{identity.Name}' is valid.");
    }
}

// Example of how to use the custom validator (conceptual)
public class ExampleUsage
{
    public static void Main(string[] args)
    {
        // Imagine this is obtained from an authentication process
        IIdentity validIdentity = new GenericIdentity("AuthorizedUser", "Basic");
        IIdentity invalidIdentity = new GenericIdentity("UnauthorizedUser", "Basic");
        IIdentity unauthenticatedIdentity = new GenericIdentity(""); // Not authenticated

        // Create an instance of our custom validator
        var validator = new SpecificUserValidator("AuthorizedUser");

        try
        {
            Console.WriteLine("Attempting to validate a valid identity:");
            validator.Validate(validIdentity);
            Console.WriteLine("Validation succeeded.\n");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Validation failed: {ex.Message}\n");
        }

        try
        {
            Console.WriteLine("Attempting to validate an invalid identity:");
            validator.Validate(invalidIdentity);
            Console.WriteLine("Validation succeeded.\n");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Validation failed: {ex.Message}\n");
        }

        try
        {
            Console.WriteLine("Attempting to validate an unauthenticated identity:");
            validator.Validate(unauthenticatedIdentity);
            Console.WriteLine("Validation succeeded.\n");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Validation failed: {ex.Message}\n");
        }
    }
}

// Custom exception for validation failures
public class IdentityNotValidException : Exception
{
    public IdentityNotValidException(string message) : base(message) { }
}

Note: This example is a simplified illustration. In a real-world application, you would integrate this validator with your network stream or authentication handler.