DES Class

 
System_CAPS_noteNote

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Represents the base class for the Data Encryption Standard (DES) algorithm from which all DES implementations must derive.

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


<ComVisibleAttribute(True)>
Public MustInherit Class DES
	Inherits SymmetricAlgorithm

NameDescription
System_CAPS_protmethodDES()

Initializes a new instance of the DES 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 secret key for the Data Encryption Standard (DES) algorithm.(Overrides SymmetricAlgorithm.Key.)

System_CAPS_pubpropertyKeySize

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

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_pubmethodSystem_CAPS_staticCreate()

Creates an instance of a cryptographic object to perform the Data Encryption Standard (DES) algorithm.

System_CAPS_pubmethodSystem_CAPS_staticCreate(String)

Creates an instance of a cryptographic object to perform the specified implementation of the Data Encryption Standard (DES) algorithm.

System_CAPS_pubmethodCreateDecryptor()

Creates a symmetric decryptor object with the current Key property and initialization vector (IV).(Inherited from SymmetricAlgorithm.)

System_CAPS_pubmethodCreateDecryptor(Byte(), Byte())

When overridden in a derived class, creates a symmetric decryptor object with the specified Key property and initialization vector (IV).(Inherited from SymmetricAlgorithm.)

System_CAPS_pubmethodCreateEncryptor()

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

System_CAPS_pubmethodCreateEncryptor(Byte(), Byte())

When overridden in a derived class, creates a symmetric encryptor object with the specified Key property and initialization vector (IV).(Inherited from SymmetricAlgorithm.)

System_CAPS_pubmethodDispose()

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

System_CAPS_protmethodDispose(Boolean)

Releases the unmanaged resources used by the SymmetricAlgorithm and optionally releases the managed resources.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubmethodEquals(Object)

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

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGenerateIV()

When overridden in a derived class, generates a random initialization vector (IV) to use for the algorithm.(Inherited from SymmetricAlgorithm.)

System_CAPS_pubmethodGenerateKey()

When overridden in a derived class, generates a random key (Key) to use for the algorithm. (Inherited from SymmetricAlgorithm.)

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_pubmethodSystem_CAPS_staticIsSemiWeakKey(Byte())

Determines whether the specified key is semi-weak.

System_CAPS_pubmethodSystem_CAPS_staticIsWeakKey(Byte())

Determines whether the specified key is weak.

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(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.)

NameDescription
System_CAPS_protfieldBlockSizeValue

Represents the block size, in bits, of the cryptographic operation.(Inherited from SymmetricAlgorithm.)

System_CAPS_protfieldFeedbackSizeValue

Represents the feedback size, in bits, of the cryptographic operation.(Inherited from SymmetricAlgorithm.)

System_CAPS_protfieldIVValue

Represents the initialization vector (IV) for the symmetric algorithm.(Inherited from SymmetricAlgorithm.)

System_CAPS_protfieldKeySizeValue

Represents the size, in bits, of the secret key used by the symmetric algorithm.(Inherited from SymmetricAlgorithm.)

System_CAPS_protfieldKeyValue

Represents the secret key for the symmetric algorithm.(Inherited from SymmetricAlgorithm.)

System_CAPS_protfieldLegalBlockSizesValue

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

System_CAPS_protfieldLegalKeySizesValue

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

System_CAPS_protfieldModeValue

Represents the cipher mode used in the symmetric algorithm.(Inherited from SymmetricAlgorithm.)

System_CAPS_protfieldPaddingValue

Represents the padding mode used in the symmetric algorithm.(Inherited from SymmetricAlgorithm.)

This algorithm supports a key length of 64 bits.

System_CAPS_noteNote

A newer asymmetric encryption algorithm, Advanced Encryption Standard (AES), is available. Consider using the Aes class instead of the DES class. Use DES only for compatibility with legacy applications and data.

The following code example uses DESCryptoServiceProvider (an implementation of DES) to encrypt a string to an in-memory buffer. It then decrypts and displays the round-tripped string.

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



Class TripleDESCryptoServiceProviderExample

    Public Shared Sub Main()
        Try

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

            ' Create a new instance of the TripleDESCryptoServiceProvider
            ' class.  This generates a new key and initialization 
            ' vector (IV).
            Using myTripleDESCryptoServiceProvider As New TripleDESCryptoServiceProvider()

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

                ' Decrypt the bytes to a string.
                Dim roundtrip As String = DecryptStringFromBytes(encrypted, myTripleDESCryptoServiceProvider.Key, myTripleDESCryptoServiceProvider.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(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 TripleDESCryptoServiceProvider object
        ' with the specified key and IV.
        Using tdsAlg As New TripleDESCryptoServiceProvider()

            tdsAlg.Key = Key
            tdsAlg.IV = IV

            ' Create a decrytor to perform the stream transform.
            Dim encryptor As ICryptoTransform = tdsAlg.CreateEncryptor(tdsAlg.Key, tdsAlg.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

    Shared Function DecryptStringFromBytes(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 TripleDESCryptoServiceProvider object
        ' with the specified key and IV.
        Using tdsAlg As New TripleDESCryptoServiceProvider
            tdsAlg.Key = Key
            tdsAlg.IV = IV

            ' Create a decrytor to perform the stream transform.
            Dim decryptor As ICryptoTransform = tdsAlg.CreateDecryptor(tdsAlg.Key, tdsAlg.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 
End Class

Decryption can be handled in the same way; use CreateDecryptor instead of CreateEncryptor. The same key (Key) and initialization vector (IV) used to encrypt the file must be used to decrypt it.

.NET Framework
Available since 1.1

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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