Imports System.Security
Imports System.Text

Module Module1

    Sub Main()
        Dim Server As New Cryptography.AesCryptoServiceProvider ' TripleDESCryptoServiceProvider ' does not work either
        Dim Client As New Cryptography.AesCryptoServiceProvider ' TripleDESCryptoServiceProvider ' does not work either

        Server.GenerateKey()
        Server.GenerateIV()
        Client.Key = Server.Key
        Client.IV = Server.IV
        ' AES2 = AES1 ' does not work either

        Dim Encryptor As Cryptography.ICryptoTransform = Server.CreateEncryptor
        Dim Decryptor As Cryptography.ICryptoTransform = Client.CreateDecryptor

        Dim SourceText As String = "One two three four five size seven eight nine ten eleven twelve." ' 64 ASCII characters
        Dim SourceBytes(0 To SourceText.Length - 1) As Byte
        Dim EncodedBytes(0 To SourceText.Length - 1) As Byte
        Dim DecodedBytes(0 To SourceText.Length - 1) As Byte
        Dim DecodedText As String

        Dim BytesProcessed As Integer
        Dim i As Integer

        Encoding.ASCII.GetBytes(SourceText, 0, SourceText.Length, SourceBytes, 0)

        i = 0

        Do While i < SourceBytes.Length
            BytesProcessed = Encryptor.TransformBlock(SourceBytes, i, Encryptor.InputBlockSize, EncodedBytes, i)
            Debug.WriteLine("Bytes encrypted: " & BytesProcessed)
            i = i + BytesProcessed
        Loop

        i = 0

        Do While i < EncodedBytes.Length
            BytesProcessed = Decryptor.TransformBlock(EncodedBytes, i, Decryptor.InputBlockSize, DecodedBytes, i)
            ' Why the hell the 1st decryption returns 0, but the 3th, 5th and so on return rubbish?
            ' When the line above is commented, the decryption result differs from the source
            BytesProcessed = Decryptor.TransformBlock(EncodedBytes, i, Decryptor.InputBlockSize, DecodedBytes, i)
            Debug.WriteLine("Bytes decrypted: " & BytesProcessed)
            i = i + BytesProcessed
        Loop

        DecodedText = Encoding.ASCII.GetString(DecodedBytes, 0, 64)

        Debug.WriteLine("Source: " & SourceText)
        Debug.WriteLine("Decoded: " & DecodedText)
        Debug.WriteLine("---")
    End Sub

End Module

Bytes encrypted: 16
Bytes encrypted: 16
Bytes encrypted: 16
Bytes encrypted: 16
Bytes decrypted: 0
Bytes decrypted: 16
Bytes decrypted: 16
Bytes decrypted: 16
Bytes decrypted: 16
Source: One two three four five size seven eight nine ten eleven twelve.
Decoded: One two three foxS??K??S2J???NUur five size seven eight nine te

Bytes encrypted: 16
Bytes encrypted: 16
Bytes encrypted: 16
Bytes encrypted: 16
Bytes decrypted: 16
Bytes decrypted: 16
Bytes decrypted: 16
Bytes decrypted: 16
Source: One two three four five size seven eight nine ten eleven twelve.
Decoded: One two three four five size seven eight nine ten eleven twelve.