عمل ترخيص سنوي لبرنامج مع تجديده كل سنة بحيث لو تغير تاريخ الجهاز يبقى عداد الايام صح

كود :
Imports System.IO

Imports System.Security.Cryptography

Imports System.Text



Module LicenseModule

    Dim encryptionKey As String = "your_encryption_key"



    Function EncryptData(ByVal data As String) As String

        Dim keyBytes() As Byte = Encoding.UTF8.GetBytes(encryptionKey)

        Dim inputBytes() As Byte = Encoding.UTF8.GetBytes(data)

        Dim hashProvider As New MD5CryptoServiceProvider()

        Dim tdesKey() As Byte = hashProvider.ComputeHash(keyBytes)

        Dim tdesAlgorithm As New TripleDESCryptoServiceProvider()

        tdesAlgorithm.Key = tdesKey

        tdesAlgorithm.Mode = CipherMode.ECB

        tdesAlgorithm.Padding = PaddingMode.PKCS7

        Dim encryptor As ICryptoTransform = tdesAlgorithm.CreateEncryptor()

        Dim results() As Byte = encryptor.TransformFinalBlock(inputBytes, 0, inputBytes.Length)

        Return Convert.ToBase64String(results)

    End Function



    Function DecryptData(ByVal data As String) As String

        Dim keyBytes() As Byte = Encoding.UTF8.GetBytes(encryptionKey)

        Dim inputBytes() As Byte = Convert.FromBase64String(data)

        Dim hashProvider As New MD5CryptoServiceProvider()

        Dim tdesKey() As Byte = hashProvider.ComputeHash(keyBytes)

        Dim tdesAlgorithm As New TripleDESCryptoServiceProvider()

        tdesAlgorithm.Key = tdesKey

        tdesAlgorithm.Mode = CipherMode.ECB

        tdesAlgorithm.Padding = PaddingMode.PKCS7

        Dim decryptor As ICryptoTransform = tdesAlgorithm.CreateDecryptor()

        Dim results() As Byte = decryptor.TransformFinalBlock(inputBytes, 0, inputBytes.Length)

        Return Encoding.UTF8.GetString(results)

    End Function



    Sub SaveLicense(ByVal startDate As DateTime, ByVal endDate As DateTime)

        Dim data As String = startDate.ToString("yyyy-MM-dd") & "|" & endDate.ToString("yyyy-MM-dd")

        Dim encryptedData As String = EncryptData(data)

        File.WriteAllText("license.dat", encryptedData)

    End Sub



    Function LoadLicense() As Tuple(Of DateTime, DateTime)

        If File.Exists("license.dat") Then

            Dim encryptedData As String = File.ReadAllText("license.dat")

            Dim data As String = DecryptData(encryptedData)

            Dim dates() As String = data.Split("|"c)

            Dim startDate As DateTime = DateTime.ParseExact(dates(0), "yyyy-MM-dd", Nothing)

            Dim endDate As DateTime = DateTime.ParseExact(dates(1), "yyyy-MM-dd", Nothing)

            Return New Tuple(Of DateTime, DateTime)(startDate, endDate)

        Else

            Return Nothing

        End If

    End Function



    Function CheckLicense() As Boolean

        Dim license As Tuple(Of DateTime, DateTime) = LoadLicense()

        If license IsNot Nothing Then

            Dim currentDate As DateTime = DateTime.Now

            If currentDate >= license.Item1 AndAlso currentDate <= license.Item2 Then

                Return True

            Else

                Return False

            End If

        Else

            Return False

        End If

    End Function

End Module