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File.Encrypt Method

Note: This method is new in the .NET Framework version 2.0.

Encrypts a file so that only the account used to encrypt the file can decrypt it.

Namespace: System.IO
Assembly: mscorlib (in mscorlib.dll)

public static void Encrypt (
	string path
public static void Encrypt (
	String path
public static function Encrypt (
	path : String



A path that describes a file to encrypt.

Exception typeCondition


The path parameter is a zero-length string, contains only white space, or contains one or more invalid characters as defined by InvalidPathChars.


The path parameter is a null reference (Nothing in Visual Basic).


An invalid drive was specified.


The file described by the path parameter could not be found.


An I/O error occurred while opening the file.


The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.


The current operating system is not Microsoft Windows NT or later.


The file system is not NTFS.


The path parameter specified a file that is read-only.


This operation is not supported on the current platform.


The path parameter specified a directory.


The caller does not have the required permission.

The Encrypt method allows you to encrypt a file so that only the account used to call this method can decrypt it. Use the Decrypt method to decrypt a file encrypted by the Encrypt method.

The Encrypt method requires exclusive access to the file being encrypted, and will fail if another process is using the file.

Both the Encrypt method and the Decrypt method use the cryptographic service provider (CSP) installed on the computer and the file encryption keys of the process calling the method.

The current file system must be formatted as NTFS and the current operating system must be Microsoft Windows NT or later.

The following code example uses the Encrypt method and the Decrypt method to encrypt and then decrypt a file.

using System;
using System.IO;
using System.Security.AccessControl;

namespace FileSystemExample
    class FileExample
        public static void Main()
                string FileName = "test.xml";

                Console.WriteLine("Enceypt " + FileName);

                // Encrypt the file.

                Console.WriteLine("Decrypt " + FileName);

                // Decrypt the file.

            catch (Exception e)


        // Encrypt a file.
        public static void AddEncryption(string FileName)



        // Decrypt a file.
        public static void RemoveEncryption(string FileName)

  • FileIOPermission  for permission to read and write to the file described by the path parameter. Associated enumerations: Read, Write Security action: Demand.

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0