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//------------------------------------------------------------------------------
// <copyright file="DpapiProtectedConfigurationProvider.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Configuration
{
using System.Collections.Specialized;
using System.Runtime.Serialization;
using System.Configuration.Provider;
using System.Xml;
using System.Text;
using System.Runtime.InteropServices;
using Microsoft.Win32;
using System.Security.Permissions;
using Microsoft.Win32.SafeHandles;
using System.Runtime.CompilerServices;
[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
public sealed class DpapiProtectedConfigurationProvider : ProtectedConfigurationProvider
{
public override XmlNode Decrypt(XmlNode encryptedNode)
{
if (encryptedNode.NodeType != XmlNodeType.Element ||
encryptedNode.Name != "EncryptedData") {
throw new ConfigurationErrorsException(SR.GetString(SR.DPAPI_bad_data));
}
XmlNode cipherNode = TraverseToChild(encryptedNode, "CipherData", false);
if (cipherNode == null)
throw new ConfigurationErrorsException(SR.GetString(SR.DPAPI_bad_data));
XmlNode cipherValue = TraverseToChild(cipherNode, "CipherValue", true);
if (cipherValue == null)
throw new ConfigurationErrorsException(SR.GetString(SR.DPAPI_bad_data));
string encText = cipherValue.InnerText;
if (encText == null)
throw new ConfigurationErrorsException(SR.GetString(SR.DPAPI_bad_data));
string decText = DecryptText(encText);
XmlDocument xmlDocument = new XmlDocument();
xmlDocument.PreserveWhitespace = true;
xmlDocument.LoadXml(decText);
return xmlDocument.DocumentElement;
}
public override XmlNode Encrypt(XmlNode node)
{
string text = node.OuterXml;
string encText = EncryptText(text);
string pre = @"<EncryptedData><CipherData><CipherValue>";
string post = @"</CipherValue></CipherData></EncryptedData>";
string xmlText = pre + encText + post;
XmlDocument xmlDocument = new XmlDocument();
xmlDocument.PreserveWhitespace = true;
xmlDocument.LoadXml(xmlText);
return xmlDocument.DocumentElement;
}
//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
private string EncryptText(string clearText)
{
if (clearText == null || clearText.Length < 1)
return clearText;
DATA_BLOB inputData, entData, outputData;
SafeNativeMemoryHandle safeInputDataHandle = new SafeNativeMemoryHandle();
SafeNativeMemoryHandle safeOutputDataHandle = new SafeNativeMemoryHandle(true);
SafeNativeMemoryHandle safeEntDataHandle = new SafeNativeMemoryHandle();
inputData.pbData = entData.pbData = outputData.pbData = IntPtr.Zero;
inputData.cbData = entData.cbData = outputData.cbData = 0;
try {
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
inputData = PrepareDataBlob(clearText);
safeInputDataHandle.SetDataHandle(inputData.pbData);
entData = PrepareDataBlob(_KeyEntropy);
safeEntDataHandle.SetDataHandle(entData.pbData);
}
CRYPTPROTECT_PROMPTSTRUCT prompt = PreparePromptStructure();
UInt32 dwFlags = CRYPTPROTECT_UI_FORBIDDEN;
if (UseMachineProtection)
dwFlags |= CRYPTPROTECT_LOCAL_MACHINE;
bool success = false;
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
success = UnsafeNativeMethods.CryptProtectData(ref inputData, "", ref entData,
IntPtr.Zero, ref prompt,
dwFlags, ref outputData);
safeOutputDataHandle.SetDataHandle(outputData.pbData);
}
if (!success || outputData.pbData == IntPtr.Zero) {
outputData.pbData = IntPtr.Zero;
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}
byte[] buf = new byte[outputData.cbData];
Marshal.Copy(outputData.pbData, buf, 0, buf.Length);
return Convert.ToBase64String(buf);
} finally {
if (!(safeOutputDataHandle == null || safeOutputDataHandle.IsInvalid)) {
safeOutputDataHandle.Dispose();
outputData.pbData = IntPtr.Zero;
}
if (!(safeEntDataHandle == null || safeEntDataHandle.IsInvalid)) {
safeEntDataHandle.Dispose();
entData.pbData = IntPtr.Zero;
}
if (!(safeInputDataHandle == null || safeInputDataHandle.IsInvalid)) {
safeInputDataHandle.Dispose();
inputData.pbData = IntPtr.Zero;
}
}
}
//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
private string DecryptText(string encText)
{
if (encText == null || encText.Length < 1)
return encText;
DATA_BLOB inputData, entData, outputData;
SafeNativeMemoryHandle safeInputDataHandle = new SafeNativeMemoryHandle();
SafeNativeMemoryHandle safeOutputDataHandle = new SafeNativeMemoryHandle(true);
SafeNativeMemoryHandle safeEntDataHandle = new SafeNativeMemoryHandle();
inputData.pbData = entData.pbData = outputData.pbData = IntPtr.Zero;
inputData.cbData = entData.cbData = outputData.cbData = 0;
try {
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
inputData = PrepareDataBlob(Convert.FromBase64String(encText));
safeInputDataHandle.SetDataHandle(inputData.pbData);
entData = PrepareDataBlob(_KeyEntropy);
safeEntDataHandle.SetDataHandle(entData.pbData);
}
CRYPTPROTECT_PROMPTSTRUCT prompt = PreparePromptStructure();
UInt32 dwFlags = CRYPTPROTECT_UI_FORBIDDEN;
if (UseMachineProtection)
dwFlags |= CRYPTPROTECT_LOCAL_MACHINE;
bool success = false;
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
success = UnsafeNativeMethods.CryptUnprotectData(ref inputData, IntPtr.Zero,
ref entData, IntPtr.Zero,
ref prompt, dwFlags, ref outputData);
safeOutputDataHandle.SetDataHandle(outputData.pbData);
}
if (!success || outputData.pbData == IntPtr.Zero) {
outputData.pbData = IntPtr.Zero;
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}
byte[] buf = new byte[outputData.cbData];
Marshal.Copy(outputData.pbData, buf, 0, buf.Length);
return Encoding.Unicode.GetString(buf);
} finally {
if (!(safeOutputDataHandle == null || safeOutputDataHandle.IsInvalid)) {
safeOutputDataHandle.Dispose();
outputData.pbData = IntPtr.Zero;
}
if (!(safeEntDataHandle == null || safeEntDataHandle.IsInvalid)) {
safeEntDataHandle.Dispose();
entData.pbData = IntPtr.Zero;
}
if (!(safeInputDataHandle == null || safeInputDataHandle.IsInvalid)) {
safeInputDataHandle.Dispose();
inputData.pbData = IntPtr.Zero;
}
}
}
public bool UseMachineProtection { get { return _UseMachineProtection; }}
//private virtual string KeyEntropy { get { return _KeyEntropy; } }
public override void Initialize(string name, NameValueCollection configurationValues)
{
base.Initialize(name, configurationValues);
_UseMachineProtection = GetBooleanValue(configurationValues, "useMachineProtection", true);
_KeyEntropy = configurationValues["keyEntropy"];
configurationValues.Remove("keyEntropy");
if (configurationValues.Count > 0)
throw new ConfigurationErrorsException(SR.GetString(SR.Unrecognized_initialization_value, configurationValues.GetKey(0)));
}
private const int CRYPTPROTECT_UI_FORBIDDEN = 0x1;
private const int CRYPTPROTECT_LOCAL_MACHINE = 0x4;
private bool _UseMachineProtection = true;
private string _KeyEntropy;
private static XmlNode TraverseToChild(XmlNode node, string name, bool onlyChild)
{
foreach (XmlNode child in node.ChildNodes)
{
if (child.NodeType != XmlNodeType.Element)
continue;
if (child.Name == name)
return child; // found it!
if (onlyChild)
return null;
}
return null;
}
private static DATA_BLOB PrepareDataBlob(byte[] buf)
{
if (buf == null)
buf = new byte[0];
DATA_BLOB db = new DATA_BLOB();
db.cbData = buf.Length;
db.pbData = Marshal.AllocHGlobal(db.cbData);
Marshal.Copy(buf, 0, db.pbData, db.cbData);
return db;
}
private static DATA_BLOB PrepareDataBlob(string s)
{
return PrepareDataBlob((s != null) ? Encoding.Unicode.GetBytes(s) : new byte[0]);
}
private static CRYPTPROTECT_PROMPTSTRUCT PreparePromptStructure()
{
CRYPTPROTECT_PROMPTSTRUCT cps = new CRYPTPROTECT_PROMPTSTRUCT();
cps.cbSize = Marshal.SizeOf(typeof(CRYPTPROTECT_PROMPTSTRUCT));
cps.dwPromptFlags = 0;
cps.hwndApp = IntPtr.Zero;
cps.szPrompt = null;
return cps;
}
private static bool GetBooleanValue(NameValueCollection configurationValues, string valueName, bool defaultValue) {
string s = configurationValues[valueName];
if (s == null)
return defaultValue;
configurationValues.Remove(valueName);
if (s == "true")
return true;
if (s == "false")
return false;
throw new ConfigurationErrorsException(SR.GetString(SR.Config_invalid_boolean_attribute, valueName));
}
}
}
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