Receiving 'The input is not a complete block' error, tried everything I can find on google. Rjindael Encryption in .NET

Question

Mornin', I'm trying to just get basic encryption working using System.Security.Cryptography.RjindaelManaged. I have google for this error and cannot find the problem, or what I am doing wrong. All I am attempting to do is encrypt a string, and then decrypt a string.

Following is my code, and any help would be appreciated.

Imports System.Security.Cryptography
Imports System.Text
Public rj As New RijndaelManaged
    Try
                rj.Padding = PaddingMode.None
                rj.GenerateKey()
                rj.GenerateIV()
                Dim curProvider As New AesCryptoServiceProvider
                Dim curEncryptor As ICryptoTransform
                Dim memEncStream As New MemoryStream
                Dim cryptoEncStream As CryptoStream
                curEncryptor = curProvider.CreateEncryptor(rj.Key, rj.IV)
                cryptoEncStream = New CryptoStream(memEncStream, curEncryptor, CryptoStreamMode.Write)
                Dim startingBytes() As Byte = Encoding.ASCII.GetBytes("This is a test")
                Debug.Print("before length: " & startingBytes.Length)
                Debug.Print("before text: " & Encoding.ASCII.GetString(startingBytes))
                cryptoEncStream.Write(startingBytes, 0, startingBytes.Length)
                cryptoEncStream.FlushFinalBlock()
                memEncStream.Position = 0
                Dim theBytes(memEncStream.Length) As Byte
                memEncStream.Read(theBytes, 0, memEncStream.Length)
                memEncStream.Flush()
                memEncStream.Close()
                cryptoEncStream.Close()
                Debug.Print("How long? " & theBytes.Length)
                Debug.Print("Data: " & Encoding.ASCII.GetString(theBytes))
                Dim curDecryptor As ICryptoTransform
                curDecryptor = curProvider.CreateDecryptor(rj.Key, rj.IV)
                Dim memDecStream As New MemoryStream
                Dim cryptoDecStream As CryptoStream
                curDecryptor = curProvider.CreateDecryptor(rj.Key, rj.IV)
                cryptoDecStream = New CryptoStream(memDecStream, curDecryptor, CryptoStreamMode.Write)
                Dim endingBytes() As Byte = theBytes
                Debug.Print("before length: " & theBytes.Length)
                Debug.Print("before text: " & Encoding.ASCII.GetString(theBytes))
                cryptoDecStream.Write(theBytes, 0, theBytes.Length)
                cryptoDecStream.FlushFinalBlock()
                memDecStream.Position = 0
                Dim endBytes(memDecStream.Length) As Byte
                memDecStream.Read(theBytes, 0, memDecStream.Length)
                memDecStream.Flush()
                memDecStream.Close()
                cryptoEncStream.Close()
                Debug.Print("How long? " & endBytes.Length)
                Debug.Print("Data: " & Encoding.ASCII.GetString(endBytes))
            Catch ex As Exception
                Debug.Print(ex.ToString)
            End Try

Answer 1

You have overridden the PaddingMode and set it None. Why? Leave the PaddingMode to its default value of PaddingMode.PKCS7 unless you have a good reason to change it and you understand padding in a block cipher.

Answer 2

It appears that the problem is the length of the data that you are passing to the decryption stream. If you change the declaration of theBytes from this:

Dim theBytes(memEncStream.Length) As Byte

To this:

Dim theBytes(memEncStream.Length - 1) As Byte

Then it runs fine (at least it did for me). I'm not a VB wizard at all, but I think the array declaration is one byte longer than the given size (I think it is 0 to N). With that extra byte passed to the decryption stream, it does not work.

And I'm sure you will see it soon enough, but your printing of the final decrypted text is not quite right. It is printing theBytes instead of endBytes.