ProtectedConfigurationProvider Class

 

Is the base class to create providers for encrypting and decrypting protected-configuration data.

Namespace:   System.Configuration
Assembly:  System.Configuration (in System.Configuration.dll)


public abstract class ProtectedConfigurationProvider : ProviderBase

NameDescription
System_CAPS_protmethodProtectedConfigurationProvider()

Initializes a new instance of the ProtectedConfigurationProvider class using default settings.

NameDescription
System_CAPS_pubpropertyDescription

Gets a brief, friendly description suitable for display in administrative tools or other user interfaces (UIs).(Inherited from ProviderBase.)

System_CAPS_pubpropertyName

Gets the friendly name used to refer to the provider during configuration.(Inherited from ProviderBase.)

NameDescription
System_CAPS_pubmethodDecrypt(XmlNode)

Decrypts the passed XmlNode object from a configuration file.

System_CAPS_pubmethodEncrypt(XmlNode)

Encrypts the passed XmlNode object from a configuration file.

System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodInitialize(String, NameValueCollection)

Initializes the provider.(Inherited from ProviderBase.)

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

You can encrypt sections of a configuration file to protect sensitive information used by your application. This improves security by making it difficult for unauthorized access even if an attacker gains access to your configuration file.

The .NET Framework includes two protected configuration providers that can be used to encrypt sections of a configuration file. The RsaProtectedConfigurationProvider class uses the RSACryptoServiceProvider to encrypt configuration sections. The DpapiProtectedConfigurationProvider class uses the Windows Data Protection API (DPAPI) to encrypt configuration sections.

You might have a requirement to encrypt sensitive information using an algorithm other than the RSA or DPAPI providers. In this case, you can build your own custom protected-configuration provider. The ProtectedConfigurationProvider is an abstract base class that you must inherit from to create your own protected-configuration provider.

Whether you use a standard or a custom provider, you must ensure that it is configured with the add element in the providers section of the configProtectedData configuration section. (See next example.)

For details, see Implementing a Protected Configuration Provider.

System_CAPS_noteNote

When ASP.NET encounters encrypted configuration data, it performs decryption transparently using the configured provider. No action is required on your side other than making sure that you configure the required provider.

The following example shows how to implement a custom ProtectedConfigurationProvider.

To be able to configure this provider, as shown in the next configuration excerpt, you must install it in the Global Assembly Cache (GAC). Refer to Implementing a Protected Configuration Provider for more information.

using System;
using System.Xml;
using System.Security.Cryptography;
using System.IO;
using System.Text;
using System.Configuration.Provider;
using System.Collections.Specialized;
using System.Configuration;

namespace Samples.AspNet
{
    // Shows how to create a custom protected configuration
    // provider.
    public class TripleDESProtectedConfigurationProvider :
        ProtectedConfigurationProvider
    {

        private TripleDESCryptoServiceProvider des =
            new TripleDESCryptoServiceProvider();

        private string pKeyFilePath;
        private string pName;

        // Gets the path of the file
        // containing the key used to
        // encryption or decryption.
        public string KeyFilePath
        {
            get { return pKeyFilePath; }
        }


        // Gets the provider name.
        public override string Name
        {
            get { return pName; }
        }


        // Performs provider initialization.
        public override void Initialize(string name,
            NameValueCollection config)
        {
            pName = name;
            pKeyFilePath = config["keyContainerName"];
            ReadKey(KeyFilePath);
        }


        // Performs encryption.
        public override XmlNode Encrypt(XmlNode node)
        {
            string encryptedData = EncryptString(node.OuterXml);

            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.PreserveWhitespace = true;
            xmlDoc.LoadXml("<EncryptedData>" +
                encryptedData + "</EncryptedData>");

            return xmlDoc.DocumentElement;
        }

        // Performs decryption.
        public override XmlNode Decrypt(XmlNode encryptedNode)
        {
            string decryptedData =
                DecryptString(encryptedNode.InnerText);

            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.PreserveWhitespace = true;
            xmlDoc.LoadXml(decryptedData);

            return xmlDoc.DocumentElement;
        }

        // Encrypts a configuration section and returns 
        // the encrypted XML as a string.
        private string EncryptString(string encryptValue)
        {
            byte[] valBytes =
                Encoding.Unicode.GetBytes(encryptValue);

            ICryptoTransform transform = des.CreateEncryptor();

            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms,
                transform, CryptoStreamMode.Write);
            cs.Write(valBytes, 0, valBytes.Length);
            cs.FlushFinalBlock();
            byte[] returnBytes = ms.ToArray();
            cs.Close();

            return Convert.ToBase64String(returnBytes);
        }


        // Decrypts an encrypted configuration section and 
        // returns the unencrypted XML as a string.
        private string DecryptString(string encryptedValue)
        {
            byte[] valBytes =
                Convert.FromBase64String(encryptedValue);

            ICryptoTransform transform = des.CreateDecryptor();

            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms,
                transform, CryptoStreamMode.Write);
            cs.Write(valBytes, 0, valBytes.Length);
            cs.FlushFinalBlock();
            byte[] returnBytes = ms.ToArray();
            cs.Close();

            return Encoding.Unicode.GetString(returnBytes);
        }

        // Generates a new TripleDES key and vector and 
        // writes them to the supplied file path.
        public void CreateKey(string filePath)
        {
            des.GenerateKey();
            des.GenerateIV();

            StreamWriter sw = new StreamWriter(filePath, false);
            sw.WriteLine(ByteToHex(des.Key));
            sw.WriteLine(ByteToHex(des.IV));
            sw.Close();
        }


        // Reads in the TripleDES key and vector from 
        // the supplied file path and sets the Key 
        // and IV properties of the 
        // TripleDESCryptoServiceProvider.
        private void ReadKey(string filePath)
        {
            StreamReader sr = new StreamReader(filePath);
            string keyValue = sr.ReadLine();
            string ivValue = sr.ReadLine();
            des.Key = HexToByte(keyValue);
            des.IV = HexToByte(ivValue);
        }


        // Converts a byte array to a hexadecimal string.
        private string ByteToHex(byte[] byteArray)
        {
            string outString = "";

            foreach (Byte b in byteArray)
                outString += b.ToString("X2");

            return outString;
        }

        // Converts a hexadecimal string to a byte array.
        private byte[] HexToByte(string hexString)
        {
            byte[] returnBytes = new byte[hexString.Length / 2];
            for (int i = 0; i < returnBytes.Length; i++)
                returnBytes[i] =
                    Convert.ToByte(hexString.Substring(i * 2, 2), 16);
            return returnBytes;
        }

    }

}

The following example shows how to use the previous custom ProtectedConfigurationProvider.

using System;
using System.Configuration;
using Samples.AspNet.Configuration;

namespace Samples.AspNet.Configuration
{

    // Show how to use a custom protected configuration
    // provider.
    public class TestingProtectedConfigurationProvider
    {

        // Protect the connectionStrings section.
        private static void ProtectConfiguration()
        {

            // Get the application configuration file.
            System.Configuration.Configuration config =
                    ConfigurationManager.OpenExeConfiguration(
                    ConfigurationUserLevel.None);

            // Define the provider name.
            string provider =
                "TripleDESProtectedConfigurationProvider";

            // Get the section to protect.
            ConfigurationSection connStrings =
                config.ConnectionStrings;

            if (connStrings != null)
            {
                if (!connStrings.SectionInformation.IsProtected)
                {
                    if (!connStrings.ElementInformation.IsLocked)
                    {
                        // Protect the section.
                        connStrings.SectionInformation.ProtectSection(provider);

                        connStrings.SectionInformation.ForceSave = true;
                        config.Save(ConfigurationSaveMode.Full);

                        Console.WriteLine("Section {0} is now protected by {1}",
                            connStrings.SectionInformation.Name,
                            connStrings.SectionInformation.ProtectionProvider.Name);

                    }
                    else
                        Console.WriteLine(
                             "Can't protect, section {0} is locked",
                             connStrings.SectionInformation.Name);
                }
                else
                    Console.WriteLine(
                        "Section {0} is already protected by {1}",
                        connStrings.SectionInformation.Name,
                        connStrings.SectionInformation.ProtectionProvider.Name);

            }
            else
                Console.WriteLine("Can't get the section {0}",
                    connStrings.SectionInformation.Name);

        }

        // Unprotect the connectionStrings section.
        private static void UnProtectConfiguration()
        {

            // Get the application configuration file.
            System.Configuration.Configuration config =
                    ConfigurationManager.OpenExeConfiguration(
                    ConfigurationUserLevel.None);

            // Get the section to unprotect.
            ConfigurationSection connStrings =
                config.ConnectionStrings;

            if (connStrings != null)
            {
                if (connStrings.SectionInformation.IsProtected)
                {
                    if (!connStrings.ElementInformation.IsLocked)
                    {
                        // Unprotect the section.
                        connStrings.SectionInformation.UnprotectSection();

                        connStrings.SectionInformation.ForceSave = true;
                        config.Save(ConfigurationSaveMode.Full);

                        Console.WriteLine("Section {0} is now unprotected.",
                            connStrings.SectionInformation.Name);

                    }
                    else
                        Console.WriteLine(
                             "Can't unprotect, section {0} is locked",
                             connStrings.SectionInformation.Name);
                }
                else
                    Console.WriteLine(
                        "Section {0} is already unprotected.",
                        connStrings.SectionInformation.Name);

            }
            else
                Console.WriteLine("Can't get the section {0}",
                    connStrings.SectionInformation.Name);

        }


        public static void Main(string[] args)
        {

            string selection = string.Empty;

            if (args.Length == 0)
            {
                Console.WriteLine(
                    "Select createkey, protect or unprotect");
                return;
            }

            selection = args[0].ToLower();

            switch (selection)
            {

                // Create the key to use during 
                // encryption/decryption.
                case "createkey":
                    string keyContainer = 
                        "pcKey.txt";

                    // Instantiate the custom provider.
                    TripleDESProtectedConfigurationProvider 
                        provider =
                        new TripleDESProtectedConfigurationProvider();

                    // Create the encryption/decryption key.
                    provider.CreateKey(keyContainer);

                    Console.WriteLine(
                        "New TripleDES key created in {0}",
                        keyContainer);
                    break;

                case "protect":
                    ProtectConfiguration();
                    break;

                case "unprotect":
                    UnProtectConfiguration();
                    break;

                default:
                    Console.WriteLine("Unknown selection");
                    break;
            }

            Console.Read();

        }


    }

}

The following is an excerpt of the configuration file used by the above examples.

<?xml version="1.0" encoding="utf-8" ?>
<configuration>

  <configProtectedData >
    <providers>
      <clear />
      <add keyContainerName="pcKey.txt" 
        name="TripleDESProtectedConfigurationProvider"
type="Samples.Aspnet.TripleDESProtectedConfigurationProvider, protectedconfigurationproviderlib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=79e01ae0f5cfc66f, processorArchitecture=MSIL" />
    </providers>

  </configProtectedData >

  <connectionStrings>
    <add name="NorthwindConnectionString" 
      connectionString="Data Source=webnetue2;Initial Catalog=Northwind;User ID=aspnet_test;Password=test"
providerName="System.Data.SqlClient" />
  </connectionStrings>

</configuration>

.NET Framework
Available since 2.0

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

Return to top
Show: