Currently, an exception is thrown when the file being unzipped already exists in the destination folder. Expose overload of the ExtractToDirectory() method allowing users to overwrite files.

Alternatively, the ZipArchiveEntry.ExtractToFile() method can be used:

using (ZipArchive source = ZipFile.Open(sourceFileName, ZipArchiveMode.Read, null))
{
    foreach (ZipArchiveEntry entry in source.Entries)
    {
        string fullPath = Path.GetFullPath(Path.Combine(destinationDirectory, entry.FullName));

        if (Path.GetFileName(fullPath).Length != 0)
        {
            Directory.CreateDirectory(Path.GetDirectoryName(fullPath));
            // The boolean parameter determines whether an existing file that has the same name as the destination file should be overwritten
            entry.ExtractToFile(fullPath, true);
        }
    }
}

7zip and the Windows arvhiver report Data Error on all the files when the users try to extract an archive created with ZipLibrary and the default LzmaSettings.

According to the specification, the Enhanced Deflating algorithm is similar to Deflate but uses a sliding dictionary of up to 64K.

Provide a way for users to check whether a stream is a valid zip archive. Include a CRC check as well.

Reading a password protected archive by passing a wrong password doesn't notify the user that the password is wrong. Accessing one of the entries in the archive throws a generic "Invalid data" exception.

Steps to reproduce:
1. Create a zip file with password.
2. Open the same archive with the API passing wrong password and then try to one of the entries.
Observed: InvalidDataException is thrown when trying to read one of the entries in the archive.
Expected: The exception should be more meaningful and if possible occur when reading the archive. There should be API allowing to check if the password is correct.

There should be API allowing to check if an archive is protected.

When updating ZIP archive, there is no need for loading it fully in the memory. Each entry is represented as a separate stream; when the ZipArchive is disposed, each entry is written in the OutputStream which is MemoryStream. When an entry is written in the OutputStream it is read from the source file if it is not changed. The MemoryStream is used because the source file is needed to get the entries contents. 

A temporary file can be used instead and there will be no need of the memory stream, so that large files will be updated without using much memory (which causes OutOfMemoryException).

Add functionality for the ZipPackage to span across multiple files.