ProtectedConfigurationProvider Class
Assembly: System.Configuration (in system.configuration.dll)
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, which uses the RSACryptoServiceProvider to encrypt configuration sections, and the DPAPIProtectedConfigurationProvider, which uses the Windows Data Protection API (DPAPI) to encrypt configuration sections.
You may 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.
Note |
|---|
| 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. |
| Topic | Location |
|---|---|
| Implementing a Protected Configuration Provider | Building ASP .NET Web Applications |
| Implementing a Protected Configuration Provider | Building ASP .NET Web Applications |
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.
Imports System Imports System.Xml Imports System.Security.Cryptography Imports System.IO Imports System.Text Imports System.Configuration.Provider Imports System.Collections.Specialized Imports System.Configuration ' Show how to use the ProtectedConfigurationProvider ' to create a custom protected configuration ' provider. Public Class TripleDESProtectedConfigurationProvider Inherits ProtectedConfigurationProvider Private des _ As New TripleDESCryptoServiceProvider() Private pKeyFilePath As String Private pName As String ' Gets the path of the file ' containing the key used to ' encrypt/decrypt. Public ReadOnly Property KeyFilePath() As String Get Return pKeyFilePath End Get End Property ' Gets the provider name. Public Overrides ReadOnly Property Name() As String Get Return pName End Get End Property ' Performs provider initialization. Public Overrides Sub Initialize( _ ByVal name As String, _ ByVal config As NameValueCollection) pName = name pKeyFilePath = config("keyContainerName") ReadKey(KeyFilePath) End Sub 'Initialize ' Performs encryption. Public Overrides Function Encrypt( _ ByVal node As XmlNode) As XmlNode Dim encryptedData As String = _ EncryptString(node.OuterXml) Dim xmlDoc As New XmlDocument() xmlDoc.PreserveWhitespace = True xmlDoc.LoadXml( _ ("<EncryptedData>" + encryptedData + _ "</EncryptedData>")) Return xmlDoc.DocumentElement End Function 'Encrypt ' Performs decryption. Public Overrides Function Decrypt( _ ByVal encryptedNode As XmlNode) As XmlNode Dim decryptedData As String = _ DecryptString(encryptedNode.InnerText) Dim xmlDoc As New XmlDocument() xmlDoc.PreserveWhitespace = True xmlDoc.LoadXml(decryptedData) Return xmlDoc.DocumentElement End Function 'Decrypt ' Encrypts a configuration section and returns ' the encrypted XML as a string. Private Function EncryptString( _ ByVal encryptValue As String) As String Dim valBytes As Byte() = _ Encoding.Unicode.GetBytes(encryptValue) Dim transform As ICryptoTransform = _ des.CreateEncryptor() Dim ms As New MemoryStream() Dim cs As New CryptoStream(ms, _ transform, CryptoStreamMode.Write) cs.Write(valBytes, 0, valBytes.Length) cs.FlushFinalBlock() Dim returnBytes As Byte() = ms.ToArray() cs.Close() Return Convert.ToBase64String(returnBytes) End Function 'EncryptString ' Decrypts an encrypted configuration section and ' returns the unencrypted XML as a string. Private Function DecryptString( _ ByVal encryptedValue As String) As String Dim valBytes As Byte() = _ Convert.FromBase64String(encryptedValue) Dim transform As ICryptoTransform = _ des.CreateDecryptor() Dim ms As New MemoryStream() Dim cs As New CryptoStream(ms, _ transform, CryptoStreamMode.Write) cs.Write(valBytes, 0, valBytes.Length) cs.FlushFinalBlock() Dim returnBytes As Byte() = ms.ToArray() cs.Close() Return Encoding.Unicode.GetString(returnBytes) End Function 'DecryptString ' Generates a new TripleDES key and vector and ' writes them to the supplied file path. Public Sub CreateKey(filePath As String) des.GenerateKey() des.GenerateIV() Dim sw As New StreamWriter(filePath, False) sw.WriteLine(ByteToHex(des.Key)) sw.WriteLine(ByteToHex(des.IV)) sw.Close() End Sub 'CreateKey ' Reads in the TripleDES key and vector from ' the supplied file path and sets the Key ' and IV properties of the ' TripleDESCryptoServiceProvider. Private Sub ReadKey(filePath As String) Dim sr As New StreamReader(filePath) Dim keyValue As String = sr.ReadLine() Dim ivValue As String = sr.ReadLine() des.Key = HexToByte(keyValue) des.IV = HexToByte(ivValue) End Sub 'ReadKey ' Converts a byte array to a hexadecimal string. Private Function ByteToHex( _ ByVal byteArray() As Byte) As String Dim outString As String = "" Dim b As [Byte] For Each b In byteArray outString += b.ToString("X2") Next b Return outString End Function 'ByteToHex ' Converts a hexadecimal string to a byte array. Private Function HexToByte(hexString As String) As Byte() Dim returnBytes(hexString.Length / 2) As Byte Dim i As Integer For i = 0 To returnBytes.Length - 1 returnBytes(i) = _ Convert.ToByte(hexString.Substring(i * 2, 2), 16) Next i Return returnBytes End Function 'HexToByte End Class 'TripleDESProtectedConfigurationProvider
The following example shows how to use the previous custom ProtectedConfigurationProvider.
Imports System Imports System.Xml Imports System.Security.Cryptography Imports System.IO Imports System.Text Imports System.Configuration.Provider Imports System.Collections.Specialized Imports System.Configuration ' Show how to use the ProtectedConfigurationProvider ' to create a custom protected configuration ' provider. Public Class TripleDESProtectedConfigurationProvider Inherits ProtectedConfigurationProvider Private des _ As New TripleDESCryptoServiceProvider() Private pKeyFilePath As String Private pName As String ' Gets the path of the file ' containing the key used to ' encrypt/decrypt. Public ReadOnly Property KeyFilePath() As String Get Return pKeyFilePath End Get End Property ' Gets the provider name. Public Overrides ReadOnly Property Name() As String Get Return pName End Get End Property ' Performs provider initialization. Public Overrides Sub Initialize( _ ByVal name As String, _ ByVal config As NameValueCollection) pName = name pKeyFilePath = config("keyContainerName") ReadKey(KeyFilePath) End Sub 'Initialize ' Performs encryption. Public Overrides Function Encrypt( _ ByVal node As XmlNode) As XmlNode Dim encryptedData As String = _ EncryptString(node.OuterXml) Dim xmlDoc As New XmlDocument() xmlDoc.PreserveWhitespace = True xmlDoc.LoadXml( _ ("<EncryptedData>" + encryptedData + _ "</EncryptedData>")) Return xmlDoc.DocumentElement End Function 'Encrypt ' Performs decryption. Public Overrides Function Decrypt( _ ByVal encryptedNode As XmlNode) As XmlNode Dim decryptedData As String = _ DecryptString(encryptedNode.InnerText) Dim xmlDoc As New XmlDocument() xmlDoc.PreserveWhitespace = True xmlDoc.LoadXml(decryptedData) Return xmlDoc.DocumentElement End Function 'Decrypt ' Encrypts a configuration section and returns ' the encrypted XML as a string. Private Function EncryptString( _ ByVal encryptValue As String) As String Dim valBytes As Byte() = _ Encoding.Unicode.GetBytes(encryptValue) Dim transform As ICryptoTransform = _ des.CreateEncryptor() Dim ms As New MemoryStream() Dim cs As New CryptoStream(ms, _ transform, CryptoStreamMode.Write) cs.Write(valBytes, 0, valBytes.Length) cs.FlushFinalBlock() Dim returnBytes As Byte() = ms.ToArray() cs.Close() Return Convert.ToBase64String(returnBytes) End Function 'EncryptString ' Decrypts an encrypted configuration section and ' returns the unencrypted XML as a string. Private Function DecryptString( _ ByVal encryptedValue As String) As String Dim valBytes As Byte() = _ Convert.FromBase64String(encryptedValue) Dim transform As ICryptoTransform = _ des.CreateDecryptor() Dim ms As New MemoryStream() Dim cs As New CryptoStream(ms, _ transform, CryptoStreamMode.Write) cs.Write(valBytes, 0, valBytes.Length) cs.FlushFinalBlock() Dim returnBytes As Byte() = ms.ToArray() cs.Close() Return Encoding.Unicode.GetString(returnBytes) End Function 'DecryptString ' Generates a new TripleDES key and vector and ' writes them to the supplied file path. Public Sub CreateKey(filePath As String) des.GenerateKey() des.GenerateIV() Dim sw As New StreamWriter(filePath, False) sw.WriteLine(ByteToHex(des.Key)) sw.WriteLine(ByteToHex(des.IV)) sw.Close() End Sub 'CreateKey ' Reads in the TripleDES key and vector from ' the supplied file path and sets the Key ' and IV properties of the ' TripleDESCryptoServiceProvider. Private Sub ReadKey(filePath As String) Dim sr As New StreamReader(filePath) Dim keyValue As String = sr.ReadLine() Dim ivValue As String = sr.ReadLine() des.Key = HexToByte(keyValue) des.IV = HexToByte(ivValue) End Sub 'ReadKey ' Converts a byte array to a hexadecimal string. Private Function ByteToHex( _ ByVal byteArray() As Byte) As String Dim outString As String = "" Dim b As [Byte] For Each b In byteArray outString += b.ToString("X2") Next b Return outString End Function 'ByteToHex ' Converts a hexadecimal string to a byte array. Private Function HexToByte(hexString As String) As Byte() Dim returnBytes(hexString.Length / 2) As Byte Dim i As Integer For i = 0 To returnBytes.Length - 1 returnBytes(i) = _ Convert.ToByte(hexString.Substring(i * 2, 2), 16) Next i Return returnBytes End Function 'HexToByte End Class 'TripleDESProtectedConfigurationProvider
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.Configuration.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>
System.Configuration.Provider.ProviderBase
System.Configuration.ProtectedConfigurationProvider
System.Configuration.DpapiProtectedConfigurationProvider
System.Configuration.RsaProtectedConfigurationProvider
Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
Reference
ProtectedConfigurationProvider MembersSystem.Configuration Namespace
ProtectedConfigurationProviderCollection
ProtectedConfiguration Class
ProtectedConfigurationSection
DpapiProtectedConfigurationProvider Class
RSAProtectedConfigurationProvider
Note