Imports System

Imports System.Text

Imports System.Security.Cryptography

Public Module Module1

​

    Public Sub Main()   

        Console.WriteLine("Encrypted: " + EncryptString("Carl"))

        Console.WriteLine("Decrypted: " + DecryptString(EncryptString("Carl")))

    End Sub

    Public Function DecryptString(EncryptedString As String) As String

        If String.IsNullOrEmpty(EncryptedString) Then

            Return String.Empty

        Else

            Return Decrypt(EncryptedString, "N3st22", "88552299", 2, "464R5DFA5DL6LE28", 256)

        End If

    End Function

    Public Function EncryptString(PlainString As String) As String

        If String.IsNullOrEmpty(PlainString) Then

            Return String.Empty

        Else

            Return Encrypt(PlainString, "N3st22", "88552299", 2, "464R5DFA5DL6LE28", 256)

        End If

    End Function

​

    Public Function Encrypt(ByVal plainText As String, _

                                   ByVal passPhrase As String, _

                                   ByVal saltValue As String, _

                                    ByVal passwordIterations As Integer, _

                                   ByVal initVector As String, _

                                   ByVal keySize As Integer) _

                           As String

​

        Dim initVectorBytes As Byte() = Encoding.ASCII.GetBytes(initVector)

        Dim saltValueBytes As Byte() = Encoding.ASCII.GetBytes(saltValue)

        Dim plainTextBytes As Byte() = Encoding.ASCII.GetBytes(plainText)

        Dim password As New Rfc2898DeriveBytes(passPhrase, _

                                           saltValueBytes, _

                                           passwordIterations)

        Dim keyBytes As Byte() = password.GetBytes(CInt(keySize / 8))

        Dim symmetricKey As New AesCryptoServiceProvider

        symmetricKey.Mode = CipherMode.CBC

        Dim encryptor As ICryptoTransform = symmetricKey.CreateEncryptor(keyBytes, initVectorBytes)

        Using memoryStream As New IO.MemoryStream()

            Using cryptoStream As New CryptoStream(memoryStream, _

                                            encryptor, _

                                            CryptoStreamMode.Write)

                cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length)

                cryptoStream.FlushFinalBlock()

                Dim cipherTextBytes As Byte() = memoryStream.ToArray()

                memoryStream.Close()

                cryptoStream.Close()

                Return Convert.ToBase64String(cipherTextBytes)

            End Using

        End Using

    End Function

    Public Function Decrypt(ByVal cipherText As String, _

                                   ByVal passPhrase As String, _

                                   ByVal saltValue As String, _

                                    ByVal passwordIterations As Integer, _

                                   ByVal initVector As String, _

                                   ByVal keySize As Integer) _

                           As String

​

        Dim initVectorBytes As Byte()

        initVectorBytes = Encoding.ASCII.GetBytes(initVector)

​

        Dim saltValueBytes As Byte()

        saltValueBytes = Encoding.ASCII.GetBytes(saltValue)

​

        Dim cipherTextBytes As Byte()

        cipherTextBytes = Convert.FromBase64String(cipherText)

​

        Dim password As New Rfc2898DeriveBytes(passPhrase, _

                                           saltValueBytes, _

                                           passwordIterations)

​

        Dim keyBytes As Byte()

        keyBytes = password.GetBytes(CInt(keySize / 8))

​

        Dim symmetricKey As New AesCryptoServiceProvider

        symmetricKey.Mode = CipherMode.CBC

​

        Dim decryptor As ICryptoTransform

        decryptor = symmetricKey.CreateDecryptor(keyBytes, initVectorBytes)

​

        Dim memoryStream As IO.MemoryStream

        memoryStream = New IO.MemoryStream(cipherTextBytes)

​

        Dim cryptoStream As CryptoStream

        cryptoStream = New CryptoStream(memoryStream, _

                                        decryptor, _

                                        CryptoStreamMode.Read)

​

        Dim plainTextBytes As Byte()

        ReDim plainTextBytes(cipherTextBytes.Length)

​

        Dim decryptedByteCount As Integer

        decryptedByteCount = cryptoStream.Read(plainTextBytes, _

                                               0, _

                                               plainTextBytes.Length)

​

        memoryStream.Close()

        cryptoStream.Close()

​

        Dim plainText As String

        plainText = Encoding.ASCII.GetString(plainTextBytes, _

                                            0, _

                                            decryptedByteCount)

​

        Return plainText

    End Function

​

End Module

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