using System; using System.IO; using System.Security.AccessControl; class MainClass { static void Main(string[] args) { FileStream stream; string fileName; fileName = Path.GetRandomFileName(); using (stream = new FileStream(fileName, FileMode.Create)) { // Do something. } SetRule(fileName, "Everyone", FileSystemRights.Read, AccessControlType.Deny); try { stream = new FileStream(fileName, FileMode.Create); } catch (Exception ex) { Console.WriteLine(ex.ToString()); } finally { stream.Close(); stream.Dispose(); } } static void AddRule(string filePath, string account, FileSystemRights rights, AccessControlType controlType) { FileSecurity fSecurity = File.GetAccessControl(filePath); fSecurity.AddAccessRule(new FileSystemAccessRule(account, rights, controlType)); File.SetAccessControl(filePath, fSecurity); } static void SetRule(string filePath, string account, FileSystemRights rights, AccessControlType controlType) { FileSecurity fSecurity = File.GetAccessControl(filePath); fSecurity.ResetAccessRule(new FileSystemAccessRule(account, rights, controlType)); File.SetAccessControl(filePath, fSecurity); } }