AesManaged Class

 

Provides a managed implementation of the Advanced Encryption Standard (AES) symmetric algorithm.

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


Public NotInheritable Class AesManaged
	Inherits Aes

NameDescription
System_CAPS_pubmethodAesManaged()

Initializes a new instance of the AesManaged class.

NameDescription
System_CAPS_pubpropertyBlockSize

Gets or sets the block size, in bits, of the cryptographic operation.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubpropertyFeedbackSize

Gets or sets the number of bits to use as feedback. (Overrides SymmetricAlgorithm.FeedbackSize.)

System_CAPS_pubpropertyIV

Gets or sets the initialization vector (IV) to use for the symmetric algorithm. (Overrides SymmetricAlgorithm.IV.)

System_CAPS_pubpropertyKey

Gets or sets the secret key used for the symmetric algorithm.(Overrides SymmetricAlgorithm.Key.)

System_CAPS_pubpropertyKeySize

Gets or sets the size, in bits, of the secret key used for the symmetric algorithm. (Overrides SymmetricAlgorithm.KeySize.)

System_CAPS_pubpropertyLegalBlockSizes

Gets the block sizes, in bits, that are supported by the symmetric algorithm.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubpropertyLegalKeySizes

Gets the key sizes, in bits, that are supported by the symmetric algorithm.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubpropertyMode

Gets or sets the mode for operation of the symmetric algorithm.(Overrides SymmetricAlgorithm.Mode.)

System_CAPS_pubpropertyPadding

Gets or sets the padding mode used in the symmetric algorithm. (Overrides SymmetricAlgorithm.Padding.)

NameDescription
System_CAPS_pubmethodClear()

Releases all resources used by the SymmetricAlgorithm class.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubmethodCreateDecryptor()

Creates a symmetric decryptor object using the current key and initialization vector (IV).(Overrides SymmetricAlgorithm.CreateDecryptor().)

System_CAPS_pubmethodCreateDecryptor(Byte(), Byte())

Creates a symmetric decryptor object using the specified key and initialization vector (IV).(Overrides SymmetricAlgorithm.CreateDecryptor(Byte(), Byte()).)

System_CAPS_pubmethodCreateEncryptor()

Creates a symmetric encryptor object using the current key and initialization vector (IV).(Overrides SymmetricAlgorithm.CreateEncryptor().)

System_CAPS_pubmethodCreateEncryptor(Byte(), Byte())

Creates a symmetric encryptor object using the specified key and initialization vector (IV).(Overrides SymmetricAlgorithm.CreateEncryptor(Byte(), Byte()).)

System_CAPS_pubmethodDispose()

Releases all resources used by the current instance of the SymmetricAlgorithm class.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_pubmethodGenerateIV()

Generates a random initialization vector (IV) to use for the symmetric algorithm.(Overrides SymmetricAlgorithm.GenerateIV().)

System_CAPS_pubmethodGenerateKey()

Generates a random key to use for the symmetric algorithm. (Overrides SymmetricAlgorithm.GenerateKey().)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubmethodValidKeySize(Int32)

Determines whether the specified key size is valid for the current algorithm.(Inherited from SymmetricAlgorithm.)

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 RijndaelManaged class but limits blocks to 128 bits and does not allow feedback modes.

System_CAPS_noteNote

If the Windows security policy setting for Federal Information Processing Standards (FIPS)-compliant algorithms is enabled, using this algorithm throws a CryptographicException.

The following example demonstrates how to encrypt and decrypt sample data using the AesManaged 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 AesManaged
            ' class.  This generates a new key and initialization 
            ' vector (IV).
            Using myAes As New AesManaged()

                ' 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("IV")
        End If
        Dim encrypted() As Byte
        ' Create an AesManaged object
        ' with the specified key and IV.
        Using aesAlg As New AesManaged()

            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("IV")
        End If
        ' Declare the string used to hold
        ' the decrypted text.
        Dim plaintext As String = Nothing

        ' Create an AesManaged object
        ' with the specified key and IV.
        Using aesAlg As New AesManaged
            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
Available since 3.5
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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