AesCryptoServiceProvider Class

 

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

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

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

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

NameDescription
System_CAPS_pubmethodAesCryptoServiceProvider()

Initializes a new instance of the AesCryptoServiceProvider 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 feedback size, in bits, of the cryptographic operation.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubpropertyIV

Gets or sets the initialization vector (IV) for the symmetric algorithm.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubpropertyKey

Gets or sets the symmetric key that is used for encryption and decryption.(Overrides SymmetricAlgorithm.Key.)

System_CAPS_pubpropertyKeySize

Gets or sets the size, in bits, of the secret key. (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.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubpropertyPadding

Gets or sets the padding mode used in the symmetric algorithm.(Inherited from SymmetricAlgorithm.)

NameDescription
System_CAPS_pubmethodClear()

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

System_CAPS_pubmethodCreateDecryptor()

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

System_CAPS_pubmethodCreateDecryptor(Byte(), Byte())

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

System_CAPS_pubmethodCreateEncryptor()

Creates a symmetric AES 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 algorithm.(Overrides SymmetricAlgorithm.GenerateIV().)

System_CAPS_pubmethodGenerateKey()

Generates a random key to use for the 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 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("IV")
        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
Available since 3.5

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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