Dim imageBuffer() As Byte
Using cipherTextStream As Stream = File.OpenRead(encryptedFile)
    Dim expression As Int32
    Dim contentLengthByteBuffer(Len(expression) - 1) As Byte
    ' Read the length of the source content file
    ' from the first four bytes of the encrypted file.
    ReliableRead(cipherTextStream, contentLengthByteBuffer, 0, Len(expression))

    ' Allocate the clearText buffer.
    Dim contentLength As Integer = BitConverter.ToInt32(contentLengthByteBuffer, 0)
    imageBuffer = New Byte(contentLength - 1) {}

    ' Allocate the cipherText block.
    Dim cipherTextBlock(cryptoProvider.BlockSize - 1) As Byte

    ' decrypt cipherText to clearText block by block.
    Dim imageBufferIndex As Integer = 0
    Do
        Dim readCount As Integer = ReliableRead(cipherTextStream, cipherTextBlock, 0, cryptoProvider.BlockSize)
        ' readCount of zero is end of data.
        If readCount = 0 Then
            Exit Do ' for
        End If

        ' Decrypt cipherText to clearText.
        Dim clearTextBlock() As Byte = cryptoProvider.Decrypt(cipherTextBlock)

        ' Copy the clearTextBlock to the imageBuffer.
        Dim copySize As Integer = Math.Min(clearTextBlock.Length, contentLength - imageBufferIndex)
        Array.Copy(clearTextBlock, 0, imageBuffer, imageBufferIndex, copySize)
        imageBufferIndex += copySize
    Loop
End Using ' end:using (Stream cipherTextStream = (close/dispose)