Question

Function MD5Hash(ByVal values As String) As Byte()
    Return MD5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(values))
End Function

Function Encrypt(ByVal Stringinput As String, ByVal key As String) As String
    des.Key = MD5Hash(key)
    des.Mode = CipherMode.ECB
    Dim buffer As Byte() = ASCIIEncoding.ASCII.GetBytes(Stringinput)
    Return Convert.ToBase64String(des.CreateEncryptor().TransformFinalBlock(buffer, 0, buffer.Length))
End Function


Private Sub btnSignup_Click(sender As Object, e As EventArgs) Handles btnSignup.Click
    Using con As New SQLiteConnection(ConnectionString.ToString)

    Dim query As String = "INSERT INTO LoginTB (user, password) VALUES (@username,@password)"
    con.Open()
        Using cmd As New SQLiteCommand(query, con)

            cmd.Parameters.AddWithValue("@username", TxtBxUsername.Text)
            cmd.Parameters.AddWithValue("@password", Encrypt(TxtBxPassword.Text, "abc"))
            cmd.ExecuteNonQuery()
            MsgBox("user created successfully")
            con.Close()
        End Using
    End Using
End Sub

当我单击注册按钮时，错误出现在MD5Hash的值中。

System.NullReferenceException'对象引用未设置为对象的实例。'

我知道有人问过很多。但是我找不到解决这个问题的方法。

Answer 1

可能由于未为MD5创建实例而引起的问题。您可以尝试如下更改功能MD5Hash的代码吗？

Function MD5Hash(ByVal values As String) As Byte()
    Static hash As MD5 = MD5.Create()
    Return hash.ComputeHash(ASCIIEncoding.ASCII.GetBytes(values))
End Function

执行时未将对象引用设置为对象的实例

1 个答案: