Public Function DecryptDes(ByVal SourceStr As String, Optional ByVal myKey As String = "", Optional ByVal myIV As String = "") As String    '使用標準DES對稱解密        If String.IsNullOrEmpty(SourceStr) Then            Return SourceStr        End If        If SourceStr = "" Then            Return SourceStr        End If        If String.IsNullOrEmpty(myKey) Then            myKey = Me.JMKey        End If        If String.IsNullOrEmpty(myIV) Then            myIV = Me.JMIv        End If        Dim des As New System.Security.Cryptography.DESCryptoServiceProvider 'DES算法        'Dim DES As New System.Security.Cryptography.TripleDESCryptoServiceProvider'TripleDES算法        des.Key = System.Text.Encoding.UTF8.GetBytes(myKey) 'myKey DES用8個字符，TripleDES要24個字符        des.IV = System.Text.Encoding.UTF8.GetBytes(myIV) 'myIV DES用8個字符，TripleDES要24個字符        Dim buffer As Byte() = Convert.FromBase64String(SourceStr)        Dim ms As New System.IO.MemoryStream(buffer)        Dim cs As New System.Security.Cryptography.CryptoStream(ms, des.CreateDecryptor(), System.Security.Cryptography.CryptoStreamMode.Read)        Dim sr As New System.IO.StreamReader(cs)        DecryptDes = sr.ReadToEnd()        Return DecryptDes    End Function請注意：不同的加密方式，密鑰長度有要求；密鑰可以寫入配置文件中，定期調整；