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SymmetricAlgorithm.CreateEncryptor Method

Updated: December 2010

Creates a symmetric encryptor object with the current Key property and initialization vector (IV).

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
Public Overridable Function CreateEncryptor As ICryptoTransform
'Usage
Dim instance As SymmetricAlgorithm 
Dim returnValue As ICryptoTransform 

returnValue = instance.CreateEncryptor()

Return Value

Type: System.Security.Cryptography.ICryptoTransform
A symmetric encryptor object.

If the current Key property is Nothing, the GenerateKey method is called to create a new random Key. If the current IV property is Nothing, the GenerateIV method is called to create a new random IV.

Use the CreateDecryptor overload with the same signature to decrypt the result of this method.

The following example encrypts a string by using the transform object that is returned from the CreateEncryptor method.

Imports System
Imports System.Security.Cryptography
Imports System.Text

Class EncryptorExample
     Private Shared quote As String = _
         "Things may come to those who wait, but only the " + _
         "things left by those who hustle. -- Abraham Lincoln" 

     Public Shared Sub Main()
         Dim aesCSP As New AesCryptoServiceProvider()

         aesCSP.GenerateKey()
         aesCSP.GenerateIV()
         Dim encQuote() As Byte = EncryptString(aesCSP, quote)

         Console.WriteLine("Encrypted Quote:" + vbNewLine)
         Console.WriteLine(Convert.ToBase64String(encQuote))

         Console.WriteLine(vbNewLine + "Decrypted Quote:" + vbNewLine)
         Console.WriteLine(DecryptBytes(aesCSP, encQuote))
     End Sub 

     Public Shared Function EncryptString(symAlg As SymmetricAlgorithm, inString As String) As Byte()
         Dim inBlock() As Byte = UnicodeEncoding.Unicode.GetBytes(inString)
         Dim xfrm As ICryptoTransform = symAlg.CreateEncryptor()
         Dim outBlock() As Byte = xfrm.TransformFinalBlock(inBlock, 0, inBlock.Length)

         Return outBlock
     End Function 

     Public Shared Function DecryptBytes(symAlg As SymmetricAlgorithm, inBytes() As Byte) As String 
         Dim xfrm As ICryptoTransform = symAlg.CreateDecryptor()
         Dim outBlock() As Byte = xfrm.TransformFinalBlock(inBytes, 0, inBytes.Length)

         return UnicodeEncoding.Unicode.GetString(outBlock)
     End Function 
End Class

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0

Date

History

Reason

December 2010

Added code example.

Customer feedback.

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