Export (0) Print
Expand All

Aes Constructor

Initializes a new instance of the Aes class.

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

'Declaration
Protected Sub New

The following example demonstrates how to encrypt and decrypt sample data using the Aes class.

Imports System
Imports System.IO
Imports System.Security.Cryptography



Class AesExample

    Public Shared Sub Main()
        Try 

            Dim original As String = "Here is some data to encrypt!" 

            ' Create a new instance of the Aes 
            ' class.  This generates a new key and initialization  
            ' vector (IV). 
            Using myAes As Aes = Aes.Create()

                ' Encrypt the string to an array of bytes. 
                Dim encrypted As Byte() = EncryptStringToBytes_Aes(original, myAes.Key, myAes.IV)

                ' Decrypt the bytes to a string. 
                Dim roundtrip As String = DecryptStringFromBytes_Aes(encrypted, myAes.Key, myAes.IV)

                'Display the original data and the decrypted data.
                Console.WriteLine("Original:   {0}", original)
                Console.WriteLine("Round Trip: {0}", roundtrip)
            End Using 
        Catch e As Exception
            Console.WriteLine("Error: {0}", e.Message)
        End Try 

    End Sub 'Main

    Shared Function EncryptStringToBytes_Aes(ByVal plainText As String, ByVal Key() As Byte, ByVal IV() As Byte) As Byte()
        ' Check arguments. 
        If plainText Is Nothing OrElse plainText.Length <= 0 Then 
            Throw New ArgumentNullException("plainText")
        End If 
        If Key Is Nothing OrElse Key.Length <= 0 Then 
            Throw New ArgumentNullException("Key")
        End If 
        If IV Is Nothing OrElse IV.Length <= 0 Then 
            Throw New ArgumentNullException("Key")
        End If 
        Dim encrypted() As Byte 
        ' Create an Aes object 
        ' with the specified key and IV. 
        Using aesAlg As Aes = Aes.Create()

            aesAlg.Key = Key
            aesAlg.IV = IV

            ' Create a decrytor to perform the stream transform. 
            Dim encryptor As ICryptoTransform = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV)
            ' Create the streams used for encryption. 
            Using msEncrypt As New MemoryStream()
                Using csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
                    Using swEncrypt As New StreamWriter(csEncrypt)

                        'Write all data to the stream.
                        swEncrypt.Write(plainText)
                    End Using
                    encrypted = msEncrypt.ToArray()
                End Using 
            End Using 
        End Using 

        ' Return the encrypted bytes from the memory stream. 
        Return encrypted

    End Function 'EncryptStringToBytes_Aes

    Shared Function DecryptStringFromBytes_Aes(ByVal cipherText() As Byte, ByVal Key() As Byte, ByVal IV() As Byte) As String 
        ' Check arguments. 
        If cipherText Is Nothing OrElse cipherText.Length <= 0 Then 
            Throw New ArgumentNullException("cipherText")
        End If 
        If Key Is Nothing OrElse Key.Length <= 0 Then 
            Throw New ArgumentNullException("Key")
        End If 
        If IV Is Nothing OrElse IV.Length <= 0 Then 
            Throw New ArgumentNullException("Key")
        End If 
        ' Declare the string used to hold 
        ' the decrypted text. 
        Dim plaintext As String = Nothing 

        ' Create an Aes object 
        ' with the specified key and IV. 
        Using aesAlg As Aes = Aes.Create()
            aesAlg.Key = Key
            aesAlg.IV = IV

            ' Create a decrytor to perform the stream transform. 
            Dim decryptor As ICryptoTransform = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV)

            ' Create the streams used for decryption. 
            Using msDecrypt As New MemoryStream(cipherText)

                Using csDecrypt As New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)

                    Using srDecrypt As New StreamReader(csDecrypt)


                        ' Read the decrypted bytes from the decrypting stream 
                        ' and place them in a string.
                        plaintext = srDecrypt.ReadToEnd()
                    End Using 
                End Using 
            End Using 
        End Using 

        Return plaintext

    End Function 'DecryptStringFromBytes_Aes 
End Class 'AesExample

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

Show:
© 2014 Microsoft