To decrypt an XML document using a certificate

xml| decryption

Imports System
Imports System.Xml
Imports System.Security.Cryptography
Imports System.Security.Cryptography.Xml
Imports System.Security.Cryptography.X509Certificates
Public Class Form1

Private Sub Form1_Load (ByVal sender as System.Object, ByVal e as System.EventArgs) Handles MyBase.Load

        ' Create an XmlDocument object.
        Dim xmldoc as New XmlDocument ()
         ' Load an XML file into the XmlDocument object.
        xmldoc.preservewhitespace = True
         xmldoc.loadxml ("<test> You can use classes in the System.Security.Cryptography.Xml namespace to encrypt the elements in an XML document.) XML encryption is a standard way to exchange or store encrypted XML data without having to worry about data being easily read. For more information about the XML Encryption standard, see the WWW Federation (World Wide Web) specification on XML encryption, located on Http://www.w3.org/TR/xmldsig-core/. </test> ")

' Open ' X.509 ' current User ' store in read only mode.
Dim Store as New X509store (Storelocation.currentuser)
Store. Open (openflags.readonly)
' Place all certificates in a X509Certificate2Collection object.
Dim certcollection as X509Certificate2Collection = store. Certificates
Dim cert as X509Certificate2 = Nothing

' Loop through each certificate and find the certificate
' With the appropriate name.
Dim C as X509Certificate2
For each C in certcollection
' If c.subject = ' CN=MASZSB ' Then
Cert = C
MsgBox (cert. Subject)
' Exit for
' End If
Next C
' If cert is nothing Then
' Throw New cryptographicexception ("The X.509 certificate could not to be found.")
' End If

' Close the store.
Store. Close ()
' Encrypt the ' creditcard ' element.
Encrypt (xmldoc, "Test", cert)

' Save the XML document.
Xmldoc.save ("C:\OK.") XML ")
' Display the encrypted XML to the console.
MsgBox ("Encrypted XML:")
MsgBox (Xmldoc.outerxml)
Decrypt (xmldoc)
MsgBox (Xmldoc.outerxml)

End Sub ' Main

Sub Encrypt (ByVal Doc as XmlDocument, ByVal Elementtoencryptname as String, ByVal Cert as X509Certificate2)
' Check the arguments.
If Doc is nothing Then
Throw New ArgumentNullException ("Doc")
End If
If Elementtoencryptname is nothing Then
Throw New ArgumentNullException ("Elementtoencrypt")
End If
If Cert is nothing Then
Throw New ArgumentNullException ("Cert")
End If
''''''''''''''''''''''''''''''''''''''''''''''''
' Find the specified element in the XmlDocument
' Object and create a new Xmlelemnt object.
''''''''''''''''''''''''''''''''''''''''''''''''
Dim Elementtoencrypt as XmlElement = Doc.getelementsbytagname (Elementtoencryptname) (0)

' Throw an XmlException if the element is not found.
If Elementtoencrypt is nothing Then
Throw New xmlexception ("The specified element is not found")
End If

            ', ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' "'
            ' Create A new instance of the Encryptedxml class
            ' and use it to encrypt the XmlElement with the
            ' X.509 certificate.
            ', ' ', ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ""
            Dim eXml as New encryptedxml ()

            ' Encrypt the element.
            Dim edelement as EncryptedData = Exml.encrypt (Elementtoencrypt, Cert)
            ', ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' "'
            ' 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)
' Check the arguments.
If Doc is nothing Then
Throw New ArgumentNullException ("Doc")
End If

' Create a new Encryptedxml object.
Dim Exml as New encryptedxml (DOC)
' Decrypt the XML document.
Exml. Decryptdocument ()
End Sub

End Class

' Of course, you can also use the Loadxml method to decrypt a piece of text