Delphi Windows Single Sign-On (SSO) Library

A lightweight Delphi library for retrieving Windows user authentication information without requiring credentials. The library provides a reliable way to get the currently logged-in Windows user's details with automatic fallback mechanisms.

Features

• Multiple Authentication Methods: Uses Windows Security API with automatic fallback to Network API
• Zero User Interaction: Retrieves user information without prompting for credentials
• Flexible Fallback Modes: Choose between strict authentication or always returning a result
• Clean Interface Design: Simple, intuitive API with proper interface-based architecture
• Cross-Platform Support: Works with both Win32 and Win64 applications
• No External Dependencies: Uses only Windows system DLLs (secur32.dll, netapi32.dll)

Installation

1. Clone this repository or download the source files
2. Add the SSO units to your Delphi project
3. Ensure your project targets Windows (Win32 or Win64)

Quick Start

Simple Usage

The easiest way to get the current Windows user:

uses
  SSO.SingleSignOn;

procedure GetCurrentUser;
begin
  TSimpleSingleSignOn.CheckUser(
    procedure(UserInfo: IWindowsUserInfo)
    begin
      if UserInfo.UserFound then
        ShowMessage('Hello, ' + UserInfo.FullQualifiedUserName)
      else
        ShowMessage('Could not determine Windows user');
    end);
end;

Advanced Usage

For more control over the authentication process:

uses
  SSO.Interfaces,
  SSO.Windows;

procedure GetUserWithFallback;
var
  SSO: ISSOComposite;
  UserInfo: IWindowsUserInfo;
begin
  SSO := TSSOWindows.Create;
  
  // Choose fallback mode
  SSO.SetFallbackMode(TFallbackMode.AlwaysReturnSomething);
  
  // Get user info
  UserInfo := SSO.GetUserInfo;
  
  if UserInfo.UserFound then
  begin
    WriteLn('Username: ', UserInfo.Username);
    WriteLn('Domain: ', UserInfo.Domain);
    WriteLn('UPN: ', UserInfo.FullQualifiedUserName);
  end;
end;

API Reference

Main Interfaces

IWindowsUserInfo

Contains the authenticated user's information:

• Username: string - The user's login name
• Domain: string - The Windows domain name
• FullQualifiedUserName: string - Full UPN (user@domain or domain\user format)
• UserFound: Boolean - Indicates if user information was successfully retrieved

ISSOComposite

Main interface for authentication:

• SetFallbackMode(Mode: TFallbackMode) - Configure fallback behavior
• GetUPN: string - Get user principal name (raises exception if not found)
• GetUserInfo: IWindowsUserInfo - Get complete user information

Fallback Modes

• TFallbackMode.Minimal - Throws exception if primary methods fail (default)
• TFallbackMode.AlwaysReturnSomething - Falls back to environment variables if needed

Authentication Methods

The library attempts authentication in the following order:

1. Windows Security API (Secur32.dll)

   • Primary method using GetUserNameEx
   • Most reliable for domain-joined computers

2. Windows Network API (NetAPI32.dll)

   • Fallback method using NetWkstaUserGetInfo
   • Works when Security API is unavailable

3. Environment Variables (optional)

   • Only used when AlwaysReturnSomething mode is enabled
   • Reads from USERNAME and USERDOMAIN environment variables

Example Application

A complete example application is included in the Examples folder. To run it:

1. Open Examples/SingleSignOnExample.dproj in Delphi
2. Compile and run the application
3. Click "Get User Info" to see the current user's details

Requirements

• Delphi/RAD Studio (tested with recent versions)
• Windows operating system (Windows 7 or later)
• Target platform: Win32 or Win64

License

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

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Support

For issues, questions, or contributions, please use the GitHub issue tracker.

Commercial Support

This library is MIT licensed and free to use. For companies that depend on it commercially we offer support and maintenance agreements with guaranteed response times, and sponsored development of features you need. Contact us at gdksoftware.com/contact-us or open an issue to get in touch.