What is the idea behind IIdentity and IPrincipal in .NET

Question

So, what is the purpose for existence of both IIdentity and IPrincipal, and not some IIdentityMergedWithPrincipal? When is it not enough t

Answer 1

public class HBPrincipal : IPrincipal
{
     private HBIdentity _identity;

     public HBPrincipal(HBIdentity identity)
    {
        _identity = identity;
    }

    public IIdentity Identity
    {
        get
        {
            return _identity;
        }
    }

    public bool IsInRole(string role)
    {
        // TODO implement roles
        return false;
    }
}