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AesCryptoServiceProvider Class

Performs symmetric encryption and decryption using the Cryptographic Application Programming Interfaces (CAPI) implementation of the Advanced Encryption Standard (AES) algorithm.

System.Object
  System.Security.Cryptography.SymmetricAlgorithm
    System.Security.Cryptography.Aes
      System.Security.Cryptography.AesCryptoServiceProvider

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

'Declaration
<HostProtectionAttribute(SecurityAction.LinkDemand, MayLeakOnAbort := True)> _
Public NotInheritable Class AesCryptoServiceProvider _
	Inherits Aes

The AesCryptoServiceProvider type exposes the following members.

  NameDescription
Public methodAesCryptoServiceProviderInitializes a new instance of the AesCryptoServiceProvider class.
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  NameDescription
Public propertyBlockSizeGets or sets the block size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm.)
Public propertyFeedbackSizeGets or sets the feedback size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm.)
Public propertyIVGets or sets the initialization vector (IV) for the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Public propertyKeyGets or sets the symmetric key that is used for encryption and decryption. (Overrides SymmetricAlgorithm.Key.)
Public propertyKeySizeGets or sets the size, in bits, of the secret key. (Overrides SymmetricAlgorithm.KeySize.)
Public propertyLegalBlockSizesGets the block sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Public propertyLegalKeySizesGets the key sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Public propertyModeGets or sets the mode for operation of the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
Public propertyPaddingGets or sets the padding mode used in the symmetric algorithm. (Inherited from SymmetricAlgorithm.)
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  NameDescription
Public methodClearReleases all resources used by the SymmetricAlgorithm class. (Inherited from SymmetricAlgorithm.)
Public methodCreateDecryptorCreates a symmetric AES decryptor object using the current key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateDecryptor.)
Public methodCreateDecryptor(Byte(), Byte())Creates a symmetric AES decryptor object using the specified key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateDecryptor(Byte(), Byte()).)
Public methodCreateEncryptorCreates a symmetric AES encryptor object using the current key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateEncryptor.)
Public methodCreateEncryptor(Byte(), Byte())Creates a symmetric encryptor object using the specified key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateEncryptor(Byte(), Byte()).)
Public methodDisposeReleases all resources used by the current instance of the SymmetricAlgorithm class. (Inherited from SymmetricAlgorithm.)
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Public methodGenerateIVGenerates a random initialization vector (IV) to use for the algorithm. (Overrides SymmetricAlgorithm.GenerateIV.)
Public methodGenerateKeyGenerates a random key to use for the algorithm. (Overrides SymmetricAlgorithm.GenerateKey.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodValidKeySizeDetermines whether the specified key size is valid for the current algorithm. (Inherited from SymmetricAlgorithm.)
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NoteNote

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: MayLeakOnAbort. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

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

                ' 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 AesCryptoServiceProvider object 
        ' with the specified key and IV. 
        Using aesAlg As New AesCryptoServiceProvider()

            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. 
            Dim 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 

        ' 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 AesCryptoServiceProvider object 
        ' with the specified key and IV. 
        Using aesAlg As New AesCryptoServiceProvider()

            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

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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