.NET 11 Preview - Generating Password-Protected Zip Archives

In some previous posts, “How To Zip A Single File In C# & .NET” and “How To Zip Multiple Files In C# & .NET”, we have looked at how to create zip files, either from a single file, a collection of files, or a directory.

However, it has not been possible to create password-protected zip files without resorting to external tools and libraries.

This has been addressed in .NET 11, using the CreateEntryFromFileAsync method.

Note: as of writing the documentation of this method is yet to be updated.

Suppose we wanted to zip the contents of the great novel War and Peace by Leo Tolstoy into a password-protected archive.

The code would look like this:

using System.IO.Compression;
using System.Reflection;
using Serilog;

// Setup logging
Log.Logger = new LoggerConfiguration()
    .WriteTo.Console()
    .CreateLogger();

// Set up the location of the target zip file
string targetZipFile =
    Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)!, "WarAndPeace.zip");
// Set up the zip file password
const string ZipFilePassword = "LeoTolstoy123%#";

// Create the archive
await using (var archive = ZipFile.Open(targetZipFile, ZipArchiveMode.Create))
{
    // Add the file to the zip archive
    await archive.CreateEntryFromFileAsync("war-and-peace.txt", "War And Peace",
        CompressionLevel.SmallestSize,
        ZipFilePassword.AsMemory(), ZipEncryptionMethod.Aes256, CancellationToken.None);

    Log.Information("Compressed file to {ZipFile}", new FileInfo(targetZipFile).Name);
}

The magic is taking place in the CreateEntryFromFileAsync method, where:

1. We provide the path to the file we want to compress
2. We provide the name we want the entry to have, in this case, War And Peace
3. We provide the password as ReadOnlyMemory<char>
4. We provide the compression level
5. We provide the encryption method

If we run this code, we should see the following:

And in the file system:

If we try to open the file:

We get a prompt asking for the password.

I find curious that the Password is a ReadOnlyMemory<char> and not a plain string. Any idea why?

TLDR

.NET 11 can now create password-protected zip files via the CreateEntryFromFileAsync method.

The code is in my GitHub.

Happy hacking!