I recently worked on a project that involved creating encrypted zip files. Data is captured on a web form and then written to a text file. At first, the task sounded complex. However, if you are aware of the DotNetZip library existence, your task just got easier.
You can download the DotNetZip
library from here. Once you download and install the package, you will need to add a reference to Ionic.Zip.dll or copy the file to your \lib folder. This is all you need to start generating your own zip files.
The best part: DotNetZip
is free!!
DotNetZip
is well documented and is much easier to use than any other solutions out there including System.IO.Compression
and SharpZipLib. After trying both methods, I would highly recommend DotNetZip
because is incredibly easy to use.
Below is a sample method to illustrate how to easily compress content that is being passed as a string
. The method takes the file name and the content as arguments:
internal MemoryStream ZipString(string aZipFileName, string aContents, string aMode)
{
try
{
string sZipFilePassword = ConfigurationManager.AppSettings["ZipFilePassword"];
string sZipFileEncryption = ConfigurationManager.AppSettings["ZipFileStrongEncryption"];
MemoryStream msZippedContent = new MemoryStream();
using (var zip = new ZipFile())
{
zip.Password = sZipFilePassword;
if (sZipFileEncryption == "N")
{
zip.Encryption = EncryptionAlgorithm.PkzipWeak;
}
else
{
zip.Encryption = EncryptionAlgorithm.WinZipAes256;
}
zip.AddEntry(aZipFileName, aContents, Encoding.ASCII);
zip.Save(msZippedContent);
return msZippedContent;
}
}
catch (Exception genEx)
{
Response.Write(genEx.Message);
return null;
}
}
The method declares a variable of type ZipFile
which is available once you add a reference: "using Ionic.Zip;
" That declaration creates the shell of the zip file. After that, the process to save the file is simple, add a password if needed, add an encryption method and you can proceed to add an entry to the zip file by using AddEntry
. Of course, you could add multiple files to the same zip archive. Finally, you can save the contents of the zip which in this case are returned by the method as a MemoryStream
that could be used for other purposes such as creating an e-mail attachment.
Be aware that if you need to encrypt the contents of the zip, choosing the encryption method is important because the built-in Windows unzip feature can only decrypt PkZip.Weak
content. You would need to have WinZip or WinRar Installed on the target workstation to unzip contents encrypted with the WinZipAes128
or WinZipAes256
methods.
Hope this is helpful. Feel free to contact me if you have any questions.
Will
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.