FileInfo::Decrypt Method ()

.NET Framework (current version)

Decrypts a file that was encrypted by the current account using the Encrypt method.

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

Syntax

public:
[ComVisibleAttribute(false)]
void Decrypt()

Exceptions

Exception	Condition
DriveNotFoundException	An invalid drive was specified.
FileNotFoundException	The file described by the current FileInfo object could not be found.
IOException	An I/O error occurred while opening the file.
NotSupportedException	The file system is not NTFS.
PlatformNotSupportedException	The current operating system is not Microsoft Windows NT or later.
UnauthorizedAccessException	The file described by the current FileInfo object is read-only. -or- This operation is not supported on the current platform. -or- The caller does not have the required permission.

Remarks

The Decrypt method allows you to decrypt a file that was encrypted using the Encrypt method. The Decrypt method can decrypt only files that were encrypted using the current user account.

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.

Examples

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

C++

using namespace System;
using namespace System::IO;
using namespace System::Security::AccessControl;


	static void Addencryption(String^ fileName)
{
    // Create a new FileInfo object.
	FileInfo^ fInfo = gcnew FileInfo(fileName);
	if (!fInfo->Exists)
	{
		fInfo->Create();
	}
	// Add encryption.
    fInfo->Encrypt();

}


	static void Removeencryption(String^ fileName)
{
//    Create a new FileInfo object.
    FileInfo^ fInfo = gcnew FileInfo(fileName);
	if (!fInfo->Exists)
	{
		fInfo->Create();
	}
    // Remove encryption.
    fInfo->Decrypt();
}

int main()
{
	try
    {
		String^ fileName = "c:\\MyTest.txt";
        Console::WriteLine("Encrypt " + fileName);

        // Encrypt the file.

		Addencryption(fileName);
		Console::WriteLine("Decrypt " + fileName);

        // Decrypt the file.
        Removeencryption(fileName);
		Console::WriteLine("Done");
     }
     catch (IOException^ ex)
     {
		Console::WriteLine(ex->Message);
     }
}
//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//Encrypt c:\MyTest.txt
//Decrypt c:\MyTest.txt
//Done

Security

FileIOPermission

Associated enumerations: Read, Write

Security action: Demand.

For permission to read and write to the file described by the current FileInfo object.

Version Information

.NET Framework
Available since 2.0