From 3bed5e7210464f87f6b2c1b0295cb1e7adb7d2c6 Mon Sep 17 00:00:00 2001
From: Tim Young <tim.young@lightsys.org>
Date: Mon, 31 Jul 2017 11:26:49 -0500
Subject: [PATCH] prep for encrypting xml

---
 EduNetworkBuilder/EduNetworkBuilder.csproj    |   2 +
 .../TrippleDESDocumentEncryption.cs           | 122 ++++++++++++++++++
 2 files changed, 124 insertions(+)
 create mode 100644 EduNetworkBuilder/TrippleDESDocumentEncryption.cs

diff --git a/EduNetworkBuilder/EduNetworkBuilder.csproj b/EduNetworkBuilder/EduNetworkBuilder.csproj
index 5864e97..f018215 100644
--- a/EduNetworkBuilder/EduNetworkBuilder.csproj
+++ b/EduNetworkBuilder/EduNetworkBuilder.csproj
@@ -72,6 +72,7 @@
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Core" />
+    <Reference Include="System.Security" />
     <Reference Include="System.Xml.Linq" />
     <Reference Include="System.Data.DataSetExtensions" />
     <Reference Include="Microsoft.CSharp" />
@@ -175,6 +176,7 @@
       <DependentUpon>RTFWindow.cs</DependentUpon>
     </Compile>
     <Compile Include="SchoolworkClass.cs" />
+    <Compile Include="TrippleDESDocumentEncryption.cs" />
     <Compile Include="VLANConfig.cs">
       <SubType>Form</SubType>
     </Compile>
diff --git a/EduNetworkBuilder/TrippleDESDocumentEncryption.cs b/EduNetworkBuilder/TrippleDESDocumentEncryption.cs
new file mode 100644
index 0000000..2544d54
--- /dev/null
+++ b/EduNetworkBuilder/TrippleDESDocumentEncryption.cs
@@ -0,0 +1,122 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Security.Cryptography;
+using System.Security.Cryptography.Xml;
+using System.Xml;
+
+namespace EduNetworkBuilder
+{
+    /// <summary>
+    /// Copied from https://msdn.microsoft.com/en-us/library/system.security.cryptography.xml.encryptedxml(v=vs.110).aspx
+    /// </summary>
+    class TrippleDESDocumentEncryption
+    {
+        protected XmlDocument docValue;
+        protected TripleDES algValue;
+
+        public TrippleDESDocumentEncryption(XmlDocument Doc, TripleDES Key)
+        {
+            if (Doc != null)
+            {
+                docValue = Doc;
+            }
+            else
+            {
+                throw new ArgumentNullException("Doc");
+            }
+
+            if (Key != null)
+            {
+
+                algValue = Key;
+            }
+            else
+            {
+                throw new ArgumentNullException("Key");
+            }
+        }
+
+        public XmlDocument Doc { set { docValue = value; } get { return docValue; } }
+        public TripleDES Alg { set { algValue = value; } get { return algValue; } }
+
+        public void Clear()
+        {
+            if (algValue != null)
+            {
+                algValue.Clear();
+            }
+            else
+            {
+                throw new Exception("No TripleDES key was found to clear.");
+            }
+        }
+
+        public void Encrypt(string Element)
+        {
+            // Find the element by name and create a new
+            // XmlElement object.
+            XmlElement inputElement = docValue.GetElementsByTagName(Element)[0] as XmlElement;
+
+            // If the element was not found, throw an exception.
+            if (inputElement == null)
+            {
+                throw new Exception("The element was not found.");
+            }
+
+            // Create a new EncryptedXml object.
+            EncryptedXml exml = new EncryptedXml(docValue);
+
+            // Encrypt the element using the symmetric key.
+            byte[] rgbOutput = exml.EncryptData(inputElement, algValue, false);
+
+            // Create an EncryptedData object and populate it.
+            EncryptedData ed = new EncryptedData();
+
+            // Specify the namespace URI for XML encryption elements.
+            ed.Type = EncryptedXml.XmlEncElementUrl;
+
+            // Specify the namespace URI for the TrippleDES algorithm.
+            ed.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncTripleDESUrl);
+
+            // Create a CipherData element.
+            ed.CipherData = new CipherData();
+
+            // Set the CipherData element to the value of the encrypted XML element.
+            ed.CipherData.CipherValue = rgbOutput;
+
+            // Replace the plaintext XML elemnt with an EncryptedData element.
+            EncryptedXml.ReplaceElement(inputElement, ed, false);
+        }
+
+        public void Decrypt()
+        {
+
+            // XmlElement object.
+            XmlElement encryptedElement = docValue.GetElementsByTagName("EncryptedData")[0] as XmlElement;
+
+            // If the EncryptedData element was not found, throw an exception.
+            if (encryptedElement == null)
+            {
+                throw new Exception("The EncryptedData element was not found.");
+            }
+
+            // Create an EncryptedData object and populate it.
+            EncryptedData ed = new EncryptedData();
+            ed.LoadXml(encryptedElement);
+
+            // Create a new EncryptedXml object.
+            EncryptedXml exml = new EncryptedXml();
+
+            // Decrypt the element using the symmetric key.
+            byte[] rgbOutput = exml.DecryptData(ed, algValue);
+
+            // Replace the encryptedData element with the plaintext XML elemnt.
+            exml.ReplaceData(encryptedElement, rgbOutput);
+
+        }
+
+    }
+}