Thread-CurrentPrincipal

    // Get and set thread's current principal (for role based security).
    // 获取并设置线程的当前主体（用于基于角色的安全性）。

        public static IPrincipal CurrentPrincipal
        {
            [System.Security.SecuritySafeCritical]  // auto-generated
            get
            {
                lock (CurrentThread)
                {
                    IPrincipal principal = (IPrincipal)
                        CallContext.Principal;
                    if (principal == null)
                    {
                        principal = GetDomain().GetThreadPrincipal();
                        CallContext.Principal = principal;
                    }
                    return principal;
                }
            }
 
            [System.Security.SecuritySafeCritical]  // auto-generated
            [SecurityPermissionAttribute(SecurityAction.Demand, Flags=SecurityPermissionFlag.ControlPrincipal)]
            set
            {
                CallContext.Principal = value;
            }
        }

CurrentPrincipal是静态属性，首先看下，Principal 

using System.Runtime.InteropServices;   
namespace System.Security.Principal
    [System.Runtime.InteropServices.ComVisible(true)]
    public interface IPrincipal {
        // Retrieve the identity object
        IIdentity Identity { get; }
 
        // Perform a check for a specific role
        bool IsInRole (string role);
    }

是在namespace System.Security.Principal下的，属于安全方面的。怎么做到安全呢？就是加上自定义名称，和认证类型，保证该线程是自己发起的，如下代码所示：

        string[] rolesArray = { "managers", "executives" };
        try
        {
            // Set the principal to a new generic principal.
            Thread.CurrentPrincipal =
                new GenericPrincipal(new GenericIdentity(
                "Bob", "Passport"), rolesArray);
        }
        catch (SecurityException secureException)
        {
            Console.WriteLine("{0}: Permission to set Principal " +
                "is denied.", secureException.GetType().Name);
        }

        IPrincipal threadPrincipal = Thread.CurrentPrincipal;
        Console.WriteLine("Name: {0}\nIsAuthenticated: {1}" +
            "\nAuthenticationType: {2}",
            threadPrincipal.Identity.Name,
            threadPrincipal.Identity.IsAuthenticated,
            threadPrincipal.Identity.AuthenticationType);

输出结果是

Name: Bob
IsAuthenticated: True
AuthenticationType: Passport
True