Question

当用户点击该按钮时，它会要求他选择一个特定的文件。它检查MD5哈希以了解这是否是正确的文件。

代码的问题是它给了我“错误的文件”消息，我完全确定该文件的MD5哈希是“3982908442F37245B305EDCF4D834494”

Private Sub Button3_Click(sender As System.Object, e As System.EventArgs) Handles Button3.Click

        dim md5code as string

        OpenFileDialog1.ShowDialog()

        Dim md5 As MD5CryptoServiceProvider = New MD5CryptoServiceProvider
        Dim f As FileStream = New FileStream(OpenFileDialog1.FileName, FileMode.Open, FileAccess.Read, FileShare.Read, 8192)
        f = New FileStream(OpenFileDialog1.FileName, FileMode.Open, FileAccess.Read, FileShare.Read, 8192)
        md5.ComputeHash(f)
        Dim ObjFSO As Object = CreateObject("Scripting.FileSystemObject")
        Dim objFile = ObjFSO.GetFile(OpenFileDialog1.FileName)

        Dim hash As Byte() = md5.Hash
        Dim buff As StringBuilder = New StringBuilder
        Dim hashByte As Byte
        For Each hashByte In hash
            buff.Append(String.Format("{0:X1}", hashByte))
        Next

        md5code = buff.ToString()

        If md5code = "3982908442F37245B305EDCF4D834494" Then
            TextBox2.Text = OpenFileDialog1.FileName
        Else
            MessageBox.Show("Wrong File")
        End If
    End Sub

Answer 1

请参阅以下MS KB文章：

HashAlgorithm.ComputeHash Method (Stream)

How to compute and compare hash values by using Visual Basic .NET or Visual Basic 2005

基本上，您需要将MD5字符串的生成更改为任一文章中概述的内容。引用第二个：

Private Function ByteArrayToString(ByVal arrInput() As Byte) As String
  Dim i As Integer
  Dim sOutput As New StringBuilder(arrInput.Length)
  For i = 0 To arrInput.Length - 1
      sOutput.Append(arrInput(i).ToString("X2"))
  Next
  Return sOutput.ToString()
End Function

您可以使用md5.Hash作为参数调用此方法，并将结果存储在md5code变量中：

md5Code = ByteArrayToString(md5.Hash)

Answer 2

更改此内容：buff.Append(String.Format("{0:X1}", hashByte))

收件人：buff.Append(String.Format("{0:X2}", hashByte))

您可以在代码中删除它：

Dim ObjFSO As Object = CreateObject("Scripting.FileSystemObject")  
Dim objFile = ObjFSO.GetFile(OpenFileDialog1.FileName)

Answer 3

粘贴以下代码进行设置：

Imports System.IO
Imports System.Security.Cryptography

Function md5(ByVal file_name As String)
    Dim hash = MD5.Create()
    Dim hashValue() As Byte
    Dim fileStream As FileStream = File.OpenRead(file_name)
    fileStream.Position = 0
    hashValue = hash.ComputeHash(fileStream)
    Dim hash_hex = PrintByteArray(hashValue)
    fileStream.Close()
    Return hash_hex
End Function

Public Function PrintByteArray(ByVal array() As Byte)
    Dim hex_value As String = ""
    Dim i As Integer
    For i = 0 To array.Length - 1
        hex_value += array(i).ToString("X2")
        Next i
        Return hex_value.ToLower
    End Function

如果要检索MD5哈希，只需使用md5(file_name)并将file_name替换为文件路径。

例如：

TextBox1.Text = md5("C:\Desktop\foo.txt")

在VB.NET中检查文件的MD5

3 个答案: