WCF UserName身份验证:我可以在自定义ServiceAuthorizationManager中获取用户名吗？

public class CustomServiceAuthorizationManager : ServiceAuthorizationManager
{
    protected override bool CheckAccessCore(OperationContext operationContext)
    {
        // 获取用户名
        string userName = GetUserName(operationContext);

        // 在这里进行授权处理
        // ...

        return true;
    }

    private string GetUserName(OperationContext operationContext)
    {
        // 获取ServiceSecurityContext
        ServiceSecurityContext securityContext = operationContext.ServiceSecurityContext;

        // 获取AuthorizationContext
        AuthorizationContext authorizationContext = securityContext.AuthorizationContext;

        // 获取用户名
        string userName = null;
        foreach (ClaimSet claimSet in authorizationContext.ClaimSets)
        {
            foreach (Claim claim in claimSet)
            {
                if (claim.Right == Rights.Identity && claim.Resource is SecurityIdentifier)
                {
                    userName = (claim.Resource as SecurityIdentifier).Translate(typeof(NTAccount)).Value;
                    break;
                }
            }
        }

        return userName;
    }
}