在vb.net中测试zip密码的正确性

Question

我想测试 zip 在 vb.net 中是否有特定的密码。如何创建像 check_if_zip_pass(file, pass) As Boolean 这样的函数？

我似乎无法在 .net 框架中找到任何已经执行此操作的内容，除非我遗漏了一些非常明显的内容。

此方法不应提取文件，仅在尝试的传递有效时返回 True，否则返回 False。

Answer 1

我在 .NET 中使用 SharpZipLib 来执行此操作，这里有一个 链接 到他们的 wiki具有用于解压缩受密码保护的 zip 文件的帮助函数。下面是 VB.NET 辅助函数的副本。

Imports ICSharpCode.SharpZipLib.Core
Imports ICSharpCode.SharpZipLib.Zip

Public Sub ExtractZipFile(archiveFilenameIn As String, password As String, outFolder As String)
    Dim zf As ZipFile = Nothing
    Try
        Dim fs As FileStream = File.OpenRead(archiveFilenameIn)
        zf = New ZipFile(fs)
        If Not [String].IsNullOrEmpty(password) Then    ' AES encrypted entries are handled automatically
            zf.Password = password
        End If
        For Each zipEntry As ZipEntry In zf
            If Not zipEntry.IsFile Then     ' Ignore directories
                Continue For
            End If
            Dim entryFileName As [String] = zipEntry.Name
            ' to remove the folder from the entry:- entryFileName = Path.GetFileName(entryFileName);
            ' Optionally match entrynames against a selection list here to skip as desired.
            ' The unpacked length is available in the zipEntry.Size property.

            Dim buffer As Byte() = New Byte(4095) {}    ' 4K is optimum
            Dim zipStream As Stream = zf.GetInputStream(zipEntry)

            ' Manipulate the output filename here as desired.
            Dim fullZipToPath As [String] = Path.Combine(outFolder, entryFileName)
            Dim directoryName As String = Path.GetDirectoryName(fullZipToPath)
            If directoryName.Length > 0 Then
                Directory.CreateDirectory(directoryName)
            End If

            ' Unzip file in buffered chunks. This is just as fast as unpacking to a buffer the full size
            ' of the file, but does not waste memory.
            ' The "Using" will close the stream even if an exception occurs.
            Using streamWriter As FileStream = File.Create(fullZipToPath)
                StreamUtils.Copy(zipStream, streamWriter, buffer)
            End Using
        Next
    Finally
        If zf IsNot Nothing Then
            zf.IsStreamOwner = True     ' Makes close also shut the underlying stream
            ' Ensure we release resources
            zf.Close()
        End If
    End Try
End Sub

为了进行测试，您可以创建一个文件比较，在压缩之前和解压之后再次查看文件（大小、日期等...）。如果您想使用简单的测试文件（例如内部带有文本“TEST”的文件），您甚至可以比较内容。有很多选择，取决于您想要测试的程度和程度。

Answer 2

框架中并没有内置太多用于执行此操作的内容。这是一个很大的混乱，您可以尝试使用 SharpZipLib 库：

public static bool CheckIfCorrectZipPassword(string fileName, string tempDirectory, string password)
{
    byte[] buffer= new byte[2048];
    int n;
    bool isValid = true;

    using (var raw = File.Open(fileName, FileMode.Open, FileAccess.Read))
    {
        using (var input = new ZipInputStream(raw))
        {
            ZipEntry e;
            while ((e = input.GetNextEntry()) != null)
            {
                input.Password = password;
                if (e.IsDirectory) continue;
                string outputPath = Path.Combine(tempDirectory, e.FileName);

                try
                {
                    using (var output = File.Open(outputPath, FileMode.Create, FileAccess.ReadWrite))
                    {
                        while ((n = input.Read(buffer, 0, buffer.Length)) > 0)
                        {
                            output.Write(buffer, 0, n);
                        }
                    }
                }
                catch (ZipException ze)
                {
                    if (ze.Message == "Invalid Password")
                    {
                        isValid = false;
                    }
                }
                finally
                {
                    if (File.Exists(outputPath))
                    {
                        // careful, this can throw exceptions
                        File.Delete(outputPath);
                    }
                }
                if (!isValid)
                {
                    break;
                }
            }
        }
    }
    return isValid;
}

Apologies for the C#;转换为 VB.NET 应该相当简单。

Answer 3

使用第 3 方库，例如 DotNetZip。请记住，zip 文件中的密码适用于条目，而不是整个 zip 文件。所以你的测试不太有意义。

WinZip 可能拒绝解压 zip 文件的一个原因是第一个条目受密码保护。可能只有某些条目受密码保护，而另一些则不受密码保护。不同的条目可能使用不同的密码。您必须决定如何应对这些可能性。

一种选择是假设 zip 文件中加密的任何条目仅使用一个密码。 （zip 规范不要求这样做）在这种情况下，下面是一些用于检查密码的示例代码。如果不进行解密，就无法检查密码。所以这段代码解密并提取到 Stream.Null 中。

public bool CheckZipPassword(string filename, string password)
{
    bool success = false;
    try
    {
        using (ZipFile zip1 = ZipFile.Read(filename))
        {
            var bitBucket = System.IO.Stream.Null;
            foreach (var e in zip1)
            {
                if (!e.IsDirectory && e.UsesEncryption)
                {
                    e.ExtractWithPassword(bitBucket, password);
                }
            }
        }
        success = true;    
    }
    catch(Ionic.Zip.BadPasswordException) { }
    return success;
}

哎呀！我认为在 C# 中。在 VB.NET 中，这将是：

    Public Function CheckZipPassword(filename As String, password As String) As System.Boolean
        Dim success As System.Boolean = False
        Try
            Using zip1 As ZipFile = ZipFile.Read(filename)
                Dim bitBucket As System.IO.Stream = System.IO.Stream.Null
                Dim e As ZipEntry
                For Each e in zip1
                    If (Not e.IsDirectory) And e.UsesEncryption Then
                        e.ExtractWithPassword(bitBucket, password)
                    End If
                Next
             End Using
             success = True
        Catch ex As Ionic.Zip.BadPasswordException
        End Try
        Return success
    End Function