SharePoint 2007 Document Encryption

Since releasing the new Advanced SharePoint Development course, I have been working on various items to add to it!  One of them is using Enterprise Library with SharePoint Event Handlers to implment document encryption!  Here is the lab!

Module #15: SharePoint Event Handlers Lab #3

 

 

Course:           Advanced SharePoint Development

Estimated Time to Complete:  45 minutes

Objectives:

·        Create an Event Handler feature that encrypts documents

Operating Notes:  none

Deliverables:

·        None

 

Overview:         SharePoint has exposed several events that we can tie into with our own code.  Let’s see how to do this!

Exercise 1 – Create a new SharePoint Event Handler

Purpose:         Create and register an event handler for SharePoint events

Result:           
A new event handler

Task 1 – Create a new Visual Studio Class Library

  1. Open Visual Studio, select New->Project
  2. Select Class Library from the project templates
  3. Name the project EncryptDocumentEventReceiver
  4. For location, c:asp
  5. Add a reference to
    • Microsoft.SharePoint.dll
    • Microsoft.Practices.EnterpriseLibrary.Common
    • Microsoft.Practices.EnterpriseLibrary.Security
    • Microsoft.Practices.EnterpriseLibrary.Security.Cryptography
  6. Add a using statement to
    • Micorosft.SharePoint
    • Microsoft.Practices.EnterpriseLibrary.Common;
    • Microsoft.Practices.EnterpriseLibrary.Common.Configuration;
    • Microsoft.Practices.EnterpriseLibrary.Security;
    • Microsoft.Practices.EnterpriseLibrary.Security.Configuration;
    • Microsoft.Practices.EnterpriseLibrary.Security.Cryptography;
  7. Rename class1 to EncryptDocument
  8. Make EncryptDocument inherit from SPItemEventReceiver
  9. Add the following methods:

private void Encrypt(SPItemEventProperties properties)

        {

            //get the file, encrypt it

            SPFile file = properties.ListItem.File;

            byte[] bytes = file.OpenBinary();

 

            //encrypt the file

            IConfigurationSource source = new SystemConfigurationSource();

            SymmetricCryptoProviderFactory factory = new SymmetricCryptoProviderFactory(source);

            ISymmetricCryptoProvider provider = factory.CreateDefault();

 

            byte[] encryptedByteArray = provider.Encrypt(bytes);

            string encryptedText = Convert.ToBase64String(encryptedByteArray);

 

            file.SaveBinary(encryptedByteArray);

            file.Update();    

        }

 

        private void Decrypt(SPItemEventProperties properties)

        {

            //get the file, encrypt it

            SPFile file = properties.ListItem.File;

            byte[] bytes = file.OpenBinary();

 

            //encrypt the file

            IConfigurationSource source = new SystemConfigurationSource();

            SymmetricCryptoProviderFactory factory = new SymmetricCryptoProviderFactory(source);

            ISymmetricCryptoProvider provider = factory.CreateDefault();

 

            byte[] decryptedByteArray = provider.Decrypt(bytes);

            string decryptedText = Convert.ToBase64String(decryptedByteArray);

 

            file.SaveBinary(decryptedByteArray);

            file.Update();           

        }

 

        public override void ItemCheckedOut(SPItemEventProperties properties)

        {

            Decrypt(properties);

 

            base.ItemCheckedOut(properties);

        }

 

        public override void ItemCheckedIn(SPItemEventProperties properties)

        {

            Encrypt(properties);

 

            base.ItemCheckedIn(properties);

        }

       

        public override void ItemAdded(SPItemEventProperties properties)

        {

            Encrypt(properties);

 

            base.ItemAdded(properties);

        }       

 

  1. Right Click the project, select Properties
  2. Select the Signing tab
  3. Click “Sign the assembly”
  4. Select <New…>, type EncryptDocumentEventReceiver.snk
  5. Uncheck “Password…”
  6. Build the project, Press Ctrl-Shift-B
  7. Copy the C:ASPEncryptDocumentEventReceiverEncryptDocumentEventReceiverinDebugEncryptDocumentEventReceiver.dll to the c:windowsassembly directory (this installs the assembly in the gac)

Task 2 – Extend the web.config file

  1. Open Enterprise Library console
  2. Click the open button, browse to the c:inetpubwwwrootwssvirtualdirectories100web.config file
  3. Click Open
  4. Right click the “C:inetpub…” node, select New->Cryptography Application Block
  5. Right click the Symmetric Provider node, select New->Symmetric Algorithm Provider
  6. Select TripleDESCryptoServiceProvider, Click Ok
  7. In the Cryptographic key wizard, Click Next
  8. Click Generate
  9. Click Next
  10. Name the key “EncryptIt.key”, Click Save
  11. Click Next
  12. Select Machine mode, Click Finish
  13. Click the Cryptography Application Block node
  14. For DefaultSymmetricCryptoProvider, select TripleDESCryptoServiceProvider

Task 3 – Create a console application to register the event handler

  1. In Visual Studio, click Add->New->Project
  2. Select a Windows Console Application
  3. Modify the Main method to this:


static void Main(string[] args)

        {

            try

            {

                SPSite site = new SPSite("http://localhost:100");

                SPWeb web = site.OpenWeb();

 

                SPEventReceiverDefinitionCollection receivers = web.EventReceivers;               

                SPEventReceiverDefinition newRecevier = receivers.Add();

                newRecevier.Name = "EncryptDocumentItemAdded";

                newRecevier.Assembly = "EncryptDocumentEventReceiver, Version=1.0.0.0, Culture=neutral,PublicKeyToken=3041621ef2536dab";

                newRecevier.Class = "EncryptDocumentEventReceiver.EncryptDocument";

                newRecevier.Type = SPEventReceiverType.ItemAdded;

                newRecevier.Update();

 

                newRecevier = receivers.Add();

                newRecevier.Name = "EncryptDocumentItemCheckedOut";

                newRecevier.Assembly = "EncryptDocumentEventReceiver, Version=1.0.0.0, Culture=neutral,PublicKeyToken=3041621ef2536dab";

                newRecevier.Class = "EncryptDocumentEventReceiver.EncryptDocument";

                newRecevier.Type = SPEventReceiverType.ItemCheckedOut;

                newRecevier.Update();

 

                newRecevier = receivers.Add();

                newRecevier.Name = "EncryptDocumentItemCheckedIn";

                newRecevier.Assembly = "EncryptDocumentEventReceiver, Version=1.0.0.0, Culture=neutral,PublicKeyToken=3041621ef2536dab";

                newRecevier.Class = "EncryptDocumentEventReceiver.EncryptDocument";

                newRecevier.Type = SPEventReceiverType.ItemCheckedIn;

                newRecevier.Update();               

            }

            catch (Exception ex)

            {

                Console.Write(ex.Message);

            }

        }

 

 

  1. Compile the project (Ctrl-Shift-B)
  2. Run the Console Project
  3. Reset IIS
  4. Open the http://localhost:100 site
  5. Create a text document, upload it to the document library
  6. Open the document, notice it is encrypted
  7. Check out the document
  8. Open the document, it is now decrypted!

 

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