变量防止更多的文本被追加到字符串

Question

我现在很失落，为什么我不能得到这么简单的工作!

我正在解密一个值&将其附加到字符串，例如

 MessageBox.Show("TEST 1: " & DecryptedValue & " WHY AM I BEING STRIPPED???")

问题是，在DecryptedValue之后的任何内容都将从字符串中剥离。

下面是一个完整的项目/表单示例，显示了这个问题的发生:

Imports System.Text
Imports System.Security.Cryptography
Imports System.IO
Public Class Form1
    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        Dim DecryptedValue As String = Decrypt("mDnz8JVmfUyYxkgZYYiFbw==", "IXZOfRxCtb4pQcu2")
        MessageBox.Show("TEST 1: " & DecryptedValue & " WHY AM I BEING STRIPPED???")
        Dim sw As New StringWriter
        sw.Write("TEST 2 ")
        sw.Write(DecryptedValue)
        sw.Write("WHY AM I BEING STRIPPED???")
        MessageBox.Show(sw.ToString())
        Dim okstr As String = "Ok"
        MessageBox.Show("When Anything " & "Else " & "Works " & okstr)
    End Sub
    Friend Function Decrypt(ByVal str As String, ByVal key As String) As String
        Dim cipher As Byte() = Convert.FromBase64String(str)
        Dim btKey As Byte() = Encoding.ASCII.GetBytes(key)
        Dim decryptor As ICryptoTransform = New RijndaelManaged() With { _
            .Mode = CipherMode.ECB, _
            .Padding = PaddingMode.None _
        }.CreateDecryptor(btKey, Nothing)
        Dim ms As New MemoryStream(cipher)
        Dim cs As New CryptoStream(ms, decryptor, CryptoStreamMode.Read)
        Dim plain As Byte() = New Byte(cipher.Length - 1) {}
        Dim count As Integer = cs.Read(plain, 0, plain.Length)
        ms.Close()
        cs.Close()
        Return Encoding.UTF8.GetString(plain, 0, count)
    End Function
End Class

有没有人在过去遇到过这个问题/可以发现我正在查看的一些非常基本的东西?

Answer 1

如果解密后的返回值包含Null (Chr(0))，则没有多少人会"看到"追加的文本。这是因为Chr(0)/Null是字符串终止字符。

Dim sb As New StringBuilder
sb.Append("first part of string" & Convert.ToChar(0))
sb.Append("this is added")
Console.WriteLine(sb.ToString)
Console.WriteLine(sb.ToString.Length)

将只显示第一部分，但长度将报告34，其中还包括嵌入的Null。创建的字符串实际上有34个字符长，但大多数内容都在Chr(0)处停止。

控制台甚至看不到在整个字符串之后发送的换行符，所以显示为:

first part of string34

有关如何/为什么工作的更多信息，请参阅