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EncryptionProperty Class

Represents the <EncryptionProperty> element used in XML encryption. This class cannot be inherited.

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

'Declaration
Public NotInheritable Class EncryptionProperty
'Usage
Dim instance As EncryptionProperty

The EncryptionProperty class encapsulates the <EncryptionProperty> element defined by the World Wide Web Consortium XML Encryption specification located at http://www.w3.org/TR/xmlenc-core/.

Use the EncryptionProperty class to provide additional encryption information related to the EncryptedData and EncryptedKey elements. For example, use this class to specify a time stamp.

The following code example encrypts and decrypts an XML document. This code example creates an EncryptionProperty object that contains custom information about the EncryptedKey element, and adds the EncryptionProperty object to the EncryptionPropertyCollection collection of the EncryptedXml class. Finally, this code example displays information about the EncryptionProperty object and the EncryptionPropertyCollection collection.

Imports System
Imports System.Xml
Imports System.Security.Cryptography
Imports System.Security.Cryptography.Xml



Module Program

    Sub Main(ByVal args() As String)

        ' Create an XmlDocument object. 
        Dim xmlDoc As New XmlDocument()

        ' Load an XML file into the XmlDocument object. 
        Try
            xmlDoc.PreserveWhitespace = True
            xmlDoc.Load("test.xml")
        Catch e As Exception
            Console.WriteLine(e.Message)
        End Try 

        ' Create a new RSA key.  This key will encrypt a symmetric key, 
        ' which will then be imbedded in the XML document.   
        Dim rsaKey As New RSACryptoServiceProvider()


        Try 
            ' Encrypt the "creditcard" element.
            Encrypt(xmlDoc, "creditcard", rsaKey, "rsaKey")

            ' Inspect the EncryptedKey element.
            InspectElement(xmlDoc)

            ' Decrypt the "creditcard" element.
            Decrypt(xmlDoc, rsaKey, "rsaKey")

        Catch e As Exception
            Console.WriteLine(e.Message)
        Finally 
            ' Clear the RSA key.
            rsaKey.Clear()
        End Try 

    End Sub 


    Sub Encrypt(ByVal Doc As XmlDocument, ByVal ElementToEncryptValue As String, ByVal Alg As RSA, ByVal KeyName As String)
        ' Check the arguments.   
        If Doc Is Nothing Then 
            Throw New ArgumentNullException("Doc")
        End If 
        If ElementToEncryptValue Is Nothing Then 
            Throw New ArgumentNullException("ElementToEncrypt")
        End If 
        If Alg Is Nothing Then 
            Throw New ArgumentNullException("Alg")
        End If 
        '''''''''''''''''''''''''''''''''''''''''''''''''' 
        ' Find the specified element in the XmlDocument 
        ' object and create a new XmlElemnt object. 
        '''''''''''''''''''''''''''''''''''''''''''''''''' 
        Dim elementToEncrypt As XmlElement = Doc.GetElementsByTagName(ElementToEncryptValue)(0)

        ' Throw an XmlException if the element was not found. 
        If elementToEncrypt Is Nothing Then 
            Throw New XmlException("The specified element was not found")
        End If 

        '''''''''''''''''''''''''''''''''''''''''''''''''' 
        ' Create a new instance of the EncryptedXml class  
        ' and use it to encrypt the XmlElement with the  
        ' a new random symmetric key. 
        '''''''''''''''''''''''''''''''''''''''''''''''''' 
        ' Create a 256 bit Rijndael key. 
        Dim sessionKey As New RijndaelManaged()
        sessionKey.KeySize = 256

        Dim eXml As New EncryptedXml()

        Dim encryptedElement As Byte() = eXml.EncryptData(elementToEncrypt, sessionKey, False)

        '''''''''''''''''''''''''''''''''''''''''''''''''' 
        ' Construct an EncryptedData object and populate 
        ' it with the desired encryption information. 
        '''''''''''''''''''''''''''''''''''''''''''''''''' 

        Dim edElement As New EncryptedData()
        edElement.Type = EncryptedXml.XmlEncElementUrl

        ' Create an EncryptionMethod element so that the  
        ' receiver knows which algorithm to use for decryption.
        edElement.EncryptionMethod = New EncryptionMethod(EncryptedXml.XmlEncAES256Url)

        ' Encrypt the session key and add it to an EncryptedKey element. 
        Dim ek As New EncryptedKey()

        Dim encryptedKey As Byte() = EncryptedXml.EncryptKey(sessionKey.Key, Alg, False)

        ek.CipherData = New CipherData(encryptedKey)

        ek.EncryptionMethod = New EncryptionMethod(EncryptedXml.XmlEncRSA15Url)

        ' Save some more information about the key using 
        ' the EncryptionProperty element.  In this example, 
        ' we will save the value "LibVersion1".  You can save 
        ' anything you want here. 
        ' Create a new "EncryptionProperty" XmlElement object.  
        Dim element As XmlElement = New XmlDocument().CreateElement("EncryptionProperty", EncryptedXml.XmlEncNamespaceUrl)

        ' Set the value of the EncryptionProperty" XmlElement object.
        element.InnerText = "LibVersion1" 

        ' Create the EncryptionProperty object using the XmlElement object.  
        Dim encProp As New EncryptionProperty(element)

        ' Add the EncryptionProperty object to the EncryptedData object.
        edElement.AddProperty(encProp)

        ' Set the KeyInfo element to specify the 
        ' name of the RSA key. 
        ' Create a new KeyInfo element.
        edElement.KeyInfo = New KeyInfo()

        ' Create a new KeyInfoName element. 
        Dim kin As New KeyInfoName()

        ' Specify a name for the key.
        kin.Value = KeyName

        ' Add the KeyInfoName element to the  
        ' EncryptedKey object.
        ek.KeyInfo.AddClause(kin)

        ' Add the encrypted key to the  
        ' EncryptedData object.
        edElement.KeyInfo.AddClause(New KeyInfoEncryptedKey(ek))

        ' Add the encrypted element data to the  
        ' EncryptedData object.
        edElement.CipherData.CipherValue = encryptedElement

        '''''''''''''''''''''''''''''''''''''''''''''''''' 
        ' Replace the element from the original XmlDocument 
        ' object with the EncryptedData element. 
        ''''''''''''''''''''''''''''''''''''''''''''''''''
        EncryptedXml.ReplaceElement(elementToEncrypt, edElement, False)

    End Sub 


    Sub Decrypt(ByVal Doc As XmlDocument, ByVal Alg As RSA, ByVal KeyName As String)
        ' Check the arguments.   
        If Doc Is Nothing Then 
            Throw New ArgumentNullException("Doc")
        End If 
        If Alg Is Nothing Then 
            Throw New ArgumentNullException("Alg")
        End If 
        If KeyName Is Nothing Then 
            Throw New ArgumentNullException("KeyName")
        End If 
        ' Create a new EncryptedXml object. 
        Dim exml As New EncryptedXml(Doc)

        ' Add a key-name mapping. 
        ' This method can only decrypt documents 
        ' that present the specified key name.
        exml.AddKeyNameMapping(KeyName, Alg)

        ' Decrypt the element.
        exml.DecryptDocument()

    End Sub 


    Sub InspectElement(ByVal Doc As XmlDocument)
        ' Get the EncryptedData element from the XMLDocument object. 
        Dim encryptedData As XmlElement = Doc.GetElementsByTagName("EncryptedData")(0)

        ' Create a new EncryptedData object. 
        Dim encData As New EncryptedData()

        ' Load the XML from the document to 
        ' initialize the EncryptedData object.
        encData.LoadXml(encryptedData)

        ' Display the properties. 
        ' Most values are Null by default.
        Console.WriteLine("EncryptedData.CipherData: " + encData.CipherData.GetXml().InnerXml)
        Console.WriteLine("EncryptedData.Encoding: " + encData.Encoding)
        Console.WriteLine("EncryptedData.EncryptionMethod: " + encData.EncryptionMethod.GetXml().InnerXml)

        Dim encPropCollection As EncryptionPropertyCollection = encData.EncryptionProperties

        Console.WriteLine("Number of elements in the EncryptionPropertyCollection: " + encPropCollection.Count.ToString())
        'encPropCollection. 
        Dim encProp As EncryptionProperty
        For Each encProp In encPropCollection
            Console.WriteLine("EncryptionProperty.ID: " + encProp.Id)
            Console.WriteLine("EncryptionProperty.PropertyElement: " + encProp.PropertyElement.InnerXml)
            Console.WriteLine("EncryptionProperty.Target: " + encProp.Target)
        Next encProp



        Console.WriteLine("EncryptedData.Id: " + encData.Id)
        Console.WriteLine("EncryptedData.KeyInfo: " + encData.KeyInfo.GetXml().InnerXml)
        Console.WriteLine("EncryptedData.MimeType: " + encData.MimeType)

    End Sub 
End Module

System.Object
  System.Security.Cryptography.Xml.EncryptionProperty

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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
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