AesManaged Class
Microsoft Silverlight will reach end of support after October 2021. Learn more.
Provides a managed implementation of the Advanced Encryption Standard (AES) symmetric algorithm.
Inheritance Hierarchy
System.Object
System.Security.Cryptography.SymmetricAlgorithm
System.Security.Cryptography.Aes
System.Security.Cryptography.AesManaged
Namespace: System.Security.Cryptography
Assembly: System.Core (in System.Core.dll)
Syntax
'Declaration
Public NotInheritable Class AesManaged _
Inherits Aes
public sealed class AesManaged : Aes
The AesManaged type exposes the following members.
Properties
Name | Description | |
---|---|---|
BlockSize | Gets or sets the block size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm.) | |
IV | Gets or sets the initialization vector (IV) to use for the symmetric algorithm. (Overrides SymmetricAlgorithm.IV.) | |
Key | Gets or sets the secret key used for the symmetric algorithm. (Overrides SymmetricAlgorithm.Key.) | |
KeySize | Gets or sets the size, in bits, of the secret key used for the symmetric algorithm. (Overrides SymmetricAlgorithm.KeySize.) | |
LegalBlockSizes | Gets the block sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.) | |
LegalKeySizes | Gets the key sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.) |
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Methods
Name | Description | |
---|---|---|
Clear | Releases all resources used by the SymmetricAlgorithm class. (Inherited from SymmetricAlgorithm.) | |
CreateDecryptor() | Creates a symmetric decryptor object using the current key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateDecryptor().) | |
CreateDecryptor(array<Byte[], array<Byte[]) | Creates a symmetric decryptor object using the specified key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateDecryptor(array<Byte[], array<Byte[]).) | |
CreateEncryptor() | Creates a symmetric encryptor object using the current key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateEncryptor().) | |
CreateEncryptor(array<Byte[], array<Byte[]) | Creates a symmetric encryptor object using the specified key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateEncryptor(array<Byte[], array<Byte[]).) | |
Dispose | Releases the unmanaged resources used by the SymmetricAlgorithm and optionally releases the managed resources. (Inherited from SymmetricAlgorithm.) | |
Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) | |
Finalize | Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.) | |
GenerateIV | Generates a random initialization vector (IV) to use for the symmetric algorithm. (Overrides SymmetricAlgorithm.GenerateIV().) | |
GenerateKey | Generates a random key to use for the symmetric algorithm. (Overrides SymmetricAlgorithm.GenerateKey().) | |
GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) | |
GetType | Gets the Type of the current instance. (Inherited from Object.) | |
MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) | |
ToString | Returns a string that represents the current object. (Inherited from Object.) | |
ValidKeySize | Determines whether the specified key size is valid for the current algorithm. (Inherited from SymmetricAlgorithm.) |
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Fields
Name | Description | |
---|---|---|
BlockSizeValue | Represents the block size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm.) | |
IVValue | Represents the initialization vector (IV) for the symmetric algorithm. (Inherited from SymmetricAlgorithm.) | |
KeySizeValue | Represents the size, in bits, of the secret key used by the symmetric algorithm. (Inherited from SymmetricAlgorithm.) | |
KeyValue | Represents the secret key for the symmetric algorithm. (Inherited from SymmetricAlgorithm.) | |
LegalBlockSizesValue | Specifies the block sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.) | |
LegalKeySizesValue | Specifies the key sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.) |
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Explicit Interface Implementations
Name | Description | |
---|---|---|
IDisposable.Dispose | Infrastructure. Releases the unmanaged resources used by the SymmetricAlgorithm and optionally releases the managed resources. (Inherited from SymmetricAlgorithm.) |
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Remarks
The AES algorithm is essentially the Rijndael symmetric algorithm with a fixed block size and iteration count. This class functions the same way as the .NET Framework RijndaelManaged class but limits blocks to 128 bits and does not allow feedback modes.
The cipher mode is always CBC, and the padding mode is always PKCS7.
Examples
The following example demonstrates how to encrypt and decrypt an isolated storage file by using the AesManaged class. To build and run this example, create a Silverlight-based application in Visual Studio named AesManaged and replace the MainPage.xaml file and the MainPage.xaml.cs (or MainPage.xaml.vb) file with the following code.
Note: |
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If the XAML code is not displayed, click the Language Filter arrow at the top of this page, and select the XAML check box. |
<UserControl x:Class="AESManaged.MainPage"
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
Width="1024" Height="768">
<Grid x:Name="LayoutRoot" Background="White" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="350" />
<ColumnDefinition Width="250" />
<!--<ColumnDefinition Width="250" />-->
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<TextBlock Grid.Row="0" Grid.Column="0" FontSize="14" Text="Enter data to encrypt"/>
<TextBlock Grid.Row="1" Grid.Column="0" FontSize="14" Text="Enter password and press Enter to encrypt" />
<TextBlock Grid.Row="2" Grid.Column="0" FontSize="14" Text="Enter file to decrypt" />
<TextBlock Grid.Row="3" Grid.Column="0" FontSize="14" Text="Enter password and press Enter to decrypt" />
<TextBlock Grid.Row="4" Grid.Column="0" FontSize="14" Text="Enter file name to delete" />
<TextBox x:Name="inputBox" Grid.Row="0" Grid.Column="1" TabIndex="0" FontSize="12" IsReadOnly="False" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<PasswordBox x:Name="passwordBox" Grid.Row="1" Grid.Column="1" TabIndex ="1" FontSize="12" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<TextBox x:Name="decryptBox" Grid.Row="2" Grid.Column="1" TabIndex="2" FontSize="12" IsReadOnly="False" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<PasswordBox x:Name="decryptPassWordBox" Grid.Row="3" TabIndex="3" Grid.Column="1" FontSize="12" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<TextBox x:Name="deleteBox" Grid.Row="4" Grid.Column="1" TabIndex="4" FontSize="12" IsReadOnly="False" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<TextBlock x:Name="outputBlock" Grid.Row="5" Grid.Column="0" FontSize="12" TextWrapping="Wrap">
</TextBlock>
</Grid>
</UserControl>
<UserControl x:Class="AESManaged.MainPage"
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
Width="1024" Height="768">
<Grid x:Name="LayoutRoot" Background="White" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="350" />
<ColumnDefinition Width="250" />
<!--<ColumnDefinition Width="250" />-->
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<TextBlock Grid.Row="0" Grid.Column="0" FontSize="14" Text="Enter data to encrypt"/>
<TextBlock Grid.Row="1" Grid.Column="0" FontSize="14" Text="Enter password and press Enter to encrypt" />
<TextBlock Grid.Row="2" Grid.Column="0" FontSize="14" Text="Enter file to decrypt" />
<TextBlock Grid.Row="3" Grid.Column="0" FontSize="14" Text="Enter password and press Enter to decrypt" />
<TextBlock Grid.Row="4" Grid.Column="0" FontSize="14" Text="Enter file name to delete" />
<TextBox x:Name="inputBox" Grid.Row="0" Grid.Column="1" TabIndex="0" FontSize="12" IsReadOnly="False" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<PasswordBox x:Name="passwordBox" Grid.Row="1" Grid.Column="1" TabIndex ="1" FontSize="12" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<TextBox x:Name="decryptBox" Grid.Row="2" Grid.Column="1" TabIndex="2" FontSize="12" IsReadOnly="False" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<PasswordBox x:Name="decryptPassWordBox" Grid.Row="3" TabIndex="3" Grid.Column="1" FontSize="12" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<TextBox x:Name="deleteBox" Grid.Row="4" Grid.Column="1" TabIndex="4" FontSize="12" IsReadOnly="False" BorderThickness="5" Height="40" Width="160" HorizontalAlignment="Center" />
<TextBlock x:Name="outputBlock" Grid.Row="5" Grid.Column="0" FontSize="12" TextWrapping="Wrap">
</TextBlock>
</Grid>
</UserControl>
Imports System
Imports System.Windows.Controls
Imports System.Windows.Input
Imports System.IO
Imports System.IO.IsolatedStorage
Imports System.Security.Cryptography
Imports System.Security.Permissions
Imports System.Text
Namespace AESManaged
Class MainPage
Inherits UserControl
Private Shared encryptedFiles As String = ""
Private Shared store As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForSite()
Private Const PasswordSalt As String = "PasswordSalt"
Private Shared intSize As Integer = 4
Public Sub New()
InitializeComponent()
AddHandler Me.inputBox.KeyDown, AddressOf inputBox_KeyDown
AddHandler Me.passwordBox.KeyDown, AddressOf passwordBox_KeyDown
AddHandler Me.decryptPassWordBox.KeyDown, AddressOf decryptPassWordBox_KeyDown
AddHandler Me.deleteBox.KeyDown, AddressOf deleteBox_KeyDown
store.CreateDirectory("MyFiles")
' Create subdirectory under MyFiles.
encryptedFiles = System.IO.Path.Combine("MyFiles", "EncryptedFiles")
store.CreateDirectory(encryptedFiles)
ListFiles()
inputBox.Focus()
End Sub 'New
Private Sub inputBox_KeyDown(ByVal sender As Object, ByVal e As EventArgs)
If CType(e, System.Windows.Input.KeyEventArgs).Key = Key.Enter Then
Me.passwordBox.Focus()
End If
End Sub 'inputBox_KeyDown
Private Sub ListFiles()
Dim searchpath As String = System.IO.Path.Combine(encryptedFiles, "*.*")
Dim filesInSubDirs As String() = store.GetFileNames(searchpath)
Dim sb As New StringBuilder()
' List files in MyFiles\EncryptedFiles.
sb.AppendLine("Files in MyFiles\EncryptedFiles:")
Dim fileName As String
For Each fileName In filesInSubDirs
sb.AppendLine(" - " + fileName)
Next fileName
sb.AppendLine()
outputBlock.Text = sb.ToString()
End Sub 'ListFiles
Private Sub deleteBox_KeyDown(ByVal sender As Object, ByVal e As EventArgs)
If CType(e, System.Windows.Input.KeyEventArgs).Key = Key.Enter Then
store.DeleteFile(encryptedFiles + "\" + deleteBox.Text)
ListFiles()
Me.passwordBox.Focus()
End If
End Sub 'deleteBox_KeyDown
Private Sub passwordBox_KeyDown(ByVal sender As Object, ByVal e As EventArgs)
If CType(e, System.Windows.Input.KeyEventArgs).Key = Key.Enter Then
Encrypt()
Me.decryptBox.Focus()
End If
End Sub 'passwordBox_KeyDown
Private Sub decryptPassWordBox_KeyDown(ByVal sender As Object, ByVal e As EventArgs)
If CType(e, System.Windows.Input.KeyEventArgs).Key = Key.Enter Then
outputBlock.Text = Decrypt()
Me.deleteBox.Focus()
End If
End Sub 'decryptPassWordBox_KeyDown
Private Function Decrypt() As String
Dim store As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication()
Dim encryptedFiles As String = System.IO.Path.Combine("MyFiles", "EncryptedFiles")
store.CreateDirectory(encryptedFiles)
Dim xFilePath As String = System.IO.Path.Combine(encryptedFiles, decryptBox.Text)
Using isoStore As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication()
Using isoStoreStream As IsolatedStorageFileStream = isoStore.OpenFile(xFilePath, FileMode.Open)
Using aes = New System.Security.Cryptography.AesManaged()
Dim deriveBytes As New Rfc2898DeriveBytes(decryptPassWordBox.Password, Encoding.UTF8.GetBytes(PasswordSalt))
aes.Key = deriveBytes.GetBytes(128 / 8)
' Get the initialization vector from the encrypted stream
aes.IV = ReadByteArray(isoStoreStream)
Dim cs As New CryptoStream(isoStoreStream, aes.CreateDecryptor(), CryptoStreamMode.Read)
Dim reader As New StreamReader(cs, Encoding.Unicode)
Try
Dim retval As String
retval = reader.ReadToEnd()
reader.Dispose()
cs.Dispose()
Return retval
Catch e As Exception
Return e.ToString()
End Try
End Using
End Using
End Using
End Function 'Decrypt
Private Sub Encrypt()
Dim store As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication()
Dim encryptedFiles As String = System.IO.Path.Combine("MyFiles", "EncryptedFiles")
store.CreateDirectory(encryptedFiles)
Dim xFilePath As String = System.IO.Path.Combine(encryptedFiles, "encryptedFile.txt")
Dim xStream As IsolatedStorageFileStream = store.CreateFile(xFilePath)
xStream.Close()
decryptBox.Text = "encryptedFile.txt"
Using isoStore As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication()
Using isoStoreStream As IsolatedStorageFileStream = isoStore.OpenFile(xFilePath, FileMode.Create)
Using aes = New System.Security.Cryptography.AesManaged()
Dim deriveBytes As New Rfc2898DeriveBytes(passwordBox.Password, Encoding.UTF8.GetBytes(PasswordSalt))
aes.Key = deriveBytes.GetBytes(128 / 8)
If Integer.MaxValue = Int64.MaxValue Then intSize = 8
isoStoreStream.Write(BitConverter.GetBytes(aes.IV.Length), 0, intSize)
isoStoreStream.Write(aes.IV, 0, aes.IV.Length)
Using cs As New CryptoStream(isoStoreStream, aes.CreateEncryptor(), CryptoStreamMode.Write)
Dim rawPlaintext As Byte() = Encoding.Unicode.GetBytes(inputBox.Text)
cs.Write(rawPlaintext, 0, rawPlaintext.Length)
cs.FlushFinalBlock()
End Using
End Using
End Using
End Using
xStream.Close()
xStream = store.OpenFile(System.IO.Path.Combine(encryptedFiles, "encryptedFile.txt"), FileMode.Open)
Dim reader As New StreamReader(xStream)
' Read the data.
Me.outputBlock.Text = reader.ReadToEnd()
reader.Close()
xStream.Close()
End Sub 'Encrypt
Private Shared Function ReadByteArray(ByVal s As Stream) As Byte()
If Integer.MaxValue = Int64.MaxValue Then intSize = 8
Dim rawLength(intSize - 1) As Byte
If s.Read(rawLength, 0, rawLength.Length) <> rawLength.Length Then
Throw New SystemException("Stream did not contain properly formatted byte array")
End If
Dim buffer(BitConverter.ToInt32(rawLength, 0) - 1) As Byte
If s.Read(buffer, 0, buffer.Length) <> buffer.Length Then
Throw New SystemException("Did not read byte array properly")
End If
Return buffer
End Function 'ReadByteArray
End Class 'Page
End Namespace
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.IO;
using System.IO.IsolatedStorage;
using System.Security.Cryptography;
using System.Security.Permissions;
using System.Text;
namespace AESManaged
{
public partial class MainPage : UserControl
{
private static string encryptedFiles = "";
private static IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForSite();
private const string PasswordSalt = "PasswordSalt";
public MainPage()
{
InitializeComponent();
this.inputBox.KeyDown += new KeyEventHandler(inputBox_KeyDown);
this.passwordBox.KeyDown += new KeyEventHandler(passwordBox_KeyDown);
this.decryptPassWordBox.KeyDown += new KeyEventHandler(decryptPassWordBox_KeyDown);
this.deleteBox.KeyDown += new KeyEventHandler(deleteBox_KeyDown);
store.CreateDirectory("MyFiles");
// Create subdirectory under MyFiles.
encryptedFiles = System.IO.Path.Combine("MyFiles", "EncryptedFiles");
store.CreateDirectory(encryptedFiles);
ListFiles();
inputBox.Focus();
}
private void inputBox_KeyDown(object sender, EventArgs e)
{
if (((System.Windows.Input.KeyEventArgs)e).Key == Key.Enter)
{
this.passwordBox.Focus();
}
}
private void ListFiles()
{
string searchpath = System.IO.Path.Combine(encryptedFiles, "*.*");
string[] filesInSubDirs = store.GetFileNames(searchpath);
StringBuilder sb = new StringBuilder();
// List files in MyFiles\EncryptedFiles.
sb.AppendLine(@"Files in MyFiles\EncryptedFiles:");
foreach (string fileName in filesInSubDirs)
{
sb.AppendLine(" - " + fileName);
}
sb.AppendLine();
outputBlock.Text = sb.ToString();
}
private void deleteBox_KeyDown(object sender, EventArgs e)
{
if (((System.Windows.Input.KeyEventArgs)e).Key == Key.Enter)
{
store.DeleteFile(encryptedFiles + "\\" + deleteBox.Text);
ListFiles();
this.passwordBox.Focus();
}
}
private void passwordBox_KeyDown(object sender, EventArgs e)
{
if (((System.Windows.Input.KeyEventArgs)e).Key == Key.Enter)
{
Encrypt();
this.decryptBox.Focus();
}
}
private void decryptPassWordBox_KeyDown(object sender, EventArgs e)
{
if (((System.Windows.Input.KeyEventArgs)e).Key == Key.Enter)
{
outputBlock.Text = Decrypt();
this.deleteBox.Focus();
}
}
private string Decrypt()
{
IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForApplication();
string encryptedFiles = System.IO.Path.Combine("MyFiles", "EncryptedFiles");
store.CreateDirectory(encryptedFiles);
string xFilePath = System.IO.Path.Combine(encryptedFiles, decryptBox.Text);
using (IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication())
using (IsolatedStorageFileStream isoStoreStream = isoStore.OpenFile(xFilePath, FileMode.Open))
{
using (Aes aes = new AesManaged())
{
Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes(decryptPassWordBox.Password, Encoding.UTF8.GetBytes(PasswordSalt));
aes.Key = deriveBytes.GetBytes(128 / 8);
// Get the initialization vector from the encrypted stream
aes.IV = ReadByteArray(isoStoreStream);
CryptoStream cs = new CryptoStream(isoStoreStream, aes.CreateDecryptor(), CryptoStreamMode.Read);
StreamReader reader = new StreamReader(cs, Encoding.Unicode);
try
{
string retval = reader.ReadToEnd();
reader.Dispose();
cs.Dispose();
return retval;
}
catch (Exception e)
{
return e.ToString();
}
}
}
}
private void Encrypt()
{
IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForApplication();
string encryptedFiles = System.IO.Path.Combine("MyFiles", "EncryptedFiles");
store.CreateDirectory(encryptedFiles);
string xFilePath = System.IO.Path.Combine(encryptedFiles, "encryptedFile.txt");
IsolatedStorageFileStream xStream = store.CreateFile(xFilePath);
xStream.Close();
decryptBox.Text = "encryptedFile.txt";
using (IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication())
using (IsolatedStorageFileStream isoStoreStream = isoStore.OpenFile(xFilePath, FileMode.Create))
{
using (Aes aes = new AesManaged())
{
Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes(passwordBox.Password, Encoding.UTF8.GetBytes(PasswordSalt));
aes.Key = deriveBytes.GetBytes(128 / 8);
isoStoreStream.Write(BitConverter.GetBytes(aes.IV.Length), 0, sizeof(int));
isoStoreStream.Write(aes.IV, 0, aes.IV.Length);
using (CryptoStream cs = new CryptoStream(isoStoreStream, aes.CreateEncryptor(), CryptoStreamMode.Write))
{
byte[] rawPlaintext = Encoding.Unicode.GetBytes(inputBox.Text);
cs.Write(rawPlaintext, 0, rawPlaintext.Length);
cs.FlushFinalBlock();
}
}
}
xStream.Close();
xStream =
store.OpenFile(System.IO.Path.Combine(encryptedFiles, "encryptedFile.txt"), FileMode.Open);
StreamReader reader = new StreamReader(xStream);
// Read the data.
this.outputBlock.Text = reader.ReadToEnd();
reader.Close();
xStream.Close();
}
private static byte[] ReadByteArray(Stream s)
{
byte[] rawLength = new byte[sizeof(int)];
if (s.Read(rawLength, 0, rawLength.Length) != rawLength.Length)
{
throw new SystemException("Stream did not contain properly formatted byte array");
}
byte[] buffer = new byte[BitConverter.ToInt32(rawLength, 0)];
if (s.Read(buffer, 0, buffer.Length) != buffer.Length)
{
throw new SystemException("Did not read byte array properly");
}
return buffer;
}
}
}
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.