This documentation is archived and is not being maintained.

ProtectedData.Protect Method

Updated: August 2010

Protects the data in a specified byte array and returns a byte array containing the encrypted data.

Namespace:  System.Security.Cryptography
Assembly:  System.Security (in System.Security.dll)

'Declaration
Public Shared Function Protect ( _
	userData As Byte(), _
	optionalEntropy As Byte(), _
	scope As DataProtectionScope _
) As Byte()
'Usage
Dim userData As Byte()
Dim optionalEntropy As Byte()
Dim scope As DataProtectionScope 
Dim returnValue As Byte()

returnValue = ProtectedData.Protect(userData, _
	optionalEntropy, scope)

Parameters

userData
Type: System.Byte()

A byte array containing data to protect.

optionalEntropy
Type: System.Byte()

An optional additional byte array used to increase the complexity of the encryption, or Nothing for no additional complexity.

scope
Type: System.Security.Cryptography.DataProtectionScope

One of the DataProtectionScope values.

Return Value

Type: System.Byte()
A byte array representing the encrypted data.

ExceptionCondition
ArgumentNullException

The userData parameter is Nothing.

CryptographicException

The cryptographic protection failed.

PlatformNotSupportedException

The operating system does not support this method.

OutOfMemoryException

The system ran out of memory while encrypting the data.

This method can be used to protect data such as passwords, keys, or connection strings. The optionalEntropy parameter enables you to use additional information to protect the data; specify Nothing for no additional complexity. This information must also be used when unprotecting the data using the Unprotect method.

NoteNote:

If you use this method during impersonation, you may receive the following error: "Key not valid for use in specified state." This error can be prevented by loading the profile of the user you want to impersonate, before calling the method.

The following code example shows how to use data protection.

Imports System
Imports System.Security.Cryptography



Public Class DataProtectionSample
    ' Create byte array for additional entropy when using Protect method. 
    Private Shared s_aditionalEntropy As Byte() = {9, 8, 7, 6, 5}


    Public Shared Sub Main()
        ' Create a simple byte array containing data to be encrypted. 
        Dim secret As Byte() = {0, 1, 2, 3, 4, 1, 2, 3, 4}

        'Encrypt the data. 
        Dim encryptedSecret As Byte() = Protect(secret)
        Console.WriteLine("The encrypted byte array is:")
        PrintValues(encryptedSecret)

        ' Decrypt the data and store in a byte array. 
        Dim originalData As Byte() = Unprotect(encryptedSecret)
        Console.WriteLine("{0}The original data is:", Environment.NewLine)
        PrintValues(originalData)

    End Sub 


    Public Shared Function Protect(ByVal data() As Byte) As Byte()
        Try 
            ' Encrypt the data using DataProtectionScope.CurrentUser. The result can be decrypted 
            '  only by the same current user. 
            Return ProtectedData.Protect(data, s_aditionalEntropy, DataProtectionScope.CurrentUser)
        Catch e As CryptographicException
            Console.WriteLine("Data was not encrypted. An error occurred.")
            Console.WriteLine(e.ToString())
            Return Nothing 
        End Try 

    End Function 


    Public Shared Function Unprotect(ByVal data() As Byte) As Byte()
        Try 
            'Decrypt the data using DataProtectionScope.CurrentUser. 
            Return ProtectedData.Unprotect(data, s_aditionalEntropy, DataProtectionScope.CurrentUser)
        Catch e As CryptographicException
            Console.WriteLine("Data was not decrypted. An error occurred.")
            Console.WriteLine(e.ToString())
            Return Nothing 
        End Try 

    End Function 


    Public Shared Sub PrintValues(ByVal myArr() As [Byte])
        Dim i As [Byte]
        For Each i In myArr
            Console.Write(vbTab + "{0}", i)
        Next i
        Console.WriteLine()

    End Sub 
End Class

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0

Date

History

Reason

August 2010

Added information about the optionalEntropy parameter.

Customer feedback.

Show: