Zip File With Password

using System;
using System.IO;
using ICSharpCode.SharpZipLib.Core;
using ICSharpCode.SharpZipLib.Zip;

// Compresses the files in the nominated folder, and creates a zip file on disk named as outPathname.
//
public void CreateSample(string outPathname, string password, string folderName) {

    FileStream fsOut = File.Create(outPathname);
    ZipOutputStream zipStream = new ZipOutputStream(fsOut);

    zipStream.SetLevel(3); //0-9, 9 being the highest level of compression

    zipStream.Password = password;  // optional. Null is the same as not setting. Required if using AES.

    // This setting will strip the leading part of the folder path in the entries, to
    // make the entries relative to the starting folder.
    // To include the full path for each entry up to the drive root, assign folderOffset = 0.
    int folderOffset = folderName.Length + (folderName.EndsWith("\\") ? 0 : 1);

    CompressFolder(folderName, zipStream, folderOffset);

    zipStream.IsStreamOwner = true; // Makes the Close also Close the underlying stream
    zipStream.Close();
}

// Recurses down the folder structure
//
private void CompressFolder(string path, ZipOutputStream zipStream, int folderOffset) {

    string[] files = Directory.GetFiles(path);

    foreach (string filename in files) {

        FileInfo fi = new FileInfo(filename);

        string entryName = filename.Substring(folderOffset); // Makes the name in zip based on the folder
        entryName = ZipEntry.CleanName(entryName); // Removes drive from name and fixes slash direction
        ZipEntry newEntry = new ZipEntry(entryName);
        newEntry.DateTime = fi.LastWriteTime; // Note the zip format stores 2 second granularity

        // Specifying the AESKeySize triggers AES encryption. Allowable values are 0 (off), 128 or 256.
                // A password on the ZipOutputStream is required if using AES.
        //   newEntry.AESKeySize = 256;

        // To permit the zip to be unpacked by built-in extractor in WinXP and Server2003, WinZip 8, Java, and other older code,
        // you need to do one of the following: Specify UseZip64.Off, or set the Size.
        // If the file may be bigger than 4GB, or you do not need WinXP built-in compatibility, you do not need either,
        // but the zip will be in Zip64 format which not all utilities can understand.
        //   zipStream.UseZip64 = UseZip64.Off;
        newEntry.Size = fi.Length;

        zipStream.PutNextEntry(newEntry);

        // Zip the file in buffered chunks
        // the "using" will close the stream even if an exception occurs
        byte[ ] buffer = new byte[4096];
        using (FileStream streamReader = File.OpenRead(filename)) {
            StreamUtils.Copy(streamReader, zipStream, buffer);
        }
        zipStream.CloseEntry();
    }
    string[ ] folders = Directory.GetDirectories(path);
    foreach (string folder in folders) {
        CompressFolder(folder, zipStream, folderOffset);
    }
}



https://github.com/icsharpcode/SharpZipLib/wiki/Zip-Samples