B4X

Encrypting and Decrypting Content

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Demonstrates how to encrypt and decrypt the content of an XML node using 128-bit CBC AES encryption.

The input XML, available at http://www.chilkatsoft.com/data/fox.xml, is this:

<root>
    <fox1>The quick brown fox jumps over the lazy dog</fox1>
    <fox2>The quick brown fox jumps over the lazy dog
        <child1>ABC</child1>
        <child2>XYZ</child2>
    </fox2>
</root>

B4X

Dim success As Boolean = False

Dim xml As ChilkatXml
xml.Initialize

'  The sample input XML is available at http://www.chilkatsoft.com/data/fox.xml
success = xml.LoadXmlFile("fox.xml")
If success <> True Then
    Log(xml.LastErrorText)
    Return
End If


'  Navigate to the "fox1" node, which is the 1st child:
success = xml.FirstChild2

'  Encrypt the content:
success = xml.EncryptContent("myPassword")

'  Navigate back to the root:
xml.GetRoot2

'  Examine the new XML document:
Log(xml.GetXml)

'  This is the XML w/ the encrypted content:
'  <root>
'      <fox1>1hTtf7XmO+78H+OIr5eWHIuXxP78KPeYrZbsD0HX4negO9ZRqYMBY4s46sPNp+Q+
'      </fox1>
'      <fox2>The quick brown fox jumps over the lazy dog
'          <child1>ABC</child1>
'          <child2>XYZ</child2>
'      </fox2>
'  </root>

'  Now decrypt and show that the original content was restored:
success = xml.FirstChild2
success = xml.DecryptContent("myPassword")
xml.GetRoot2
Log(xml.GetXml)

'  Now encrypt the content of the "fox2" node.
'  First navigate to the "fox2" child.
success = xml.FindChild2("fox2")
success = xml.EncryptContent("myPassword")
xml.GetRoot2
Log(xml.GetXml)

'  This is the XML w/ the "fox2" encrypted content:

'  <root>
'      <fox1>The quick brown fox jumps over the lazy dog</fox1>
'      <fox2>1hTtf7XmO+78H+OIr5eWHIuXxP78KPeYrZbsD0HX4negO9ZRqYMBY4s46sPNp+Q+
'  
'          <child1>ABC</child1>
'          <child2>XYZ</child2>
'      </fox2>
'  </root>

'  Notice that the *content* of the node is encrypted.  The child nodes are NOT encrypted.
'  This is intentional.  To encrypt the content + the subtrees rooted at a given node, 
'  one would call ZipTree to transform the content and subtrees
'  to Base64-encoded compressed content, and then call
'  EncryptContent to encrypt.

'  Finally, decrypt the "fox2" content:
success = xml.FindChild2("fox2")
success = xml.DecryptContent("myPassword")
xml.GetRoot2
Log(xml.GetXml)