Are there any compression and encryption libraries in C#?

Question

I want to compress some files (into the ZIP format) and encrypt them if possible using C#. Is there some way to do this?

Can encryption be done as a part of the compression itself?

Answer 1

For compression, look at the System.IO.Compression namespace and for encryption look at System.Security.Cryptography.

Answer 2

For Zip Compression, have you seen http://www.icsharpcode.net/OpenSource/SharpZipLib/

Answer 3

I know the question is already old, but I must add my two cents.

First, some definitions:

• Zip: Archive format for regrouping files and folders into a single file, and optionally encrypting data.
• Deflate: One of the compression algorithms used within a Zip file to compress the data. The most popular one.
• GZip: A single file compressed with deflate, with a small header and footer.

Now, System.IO.Compression does not do Zip archiving. It does deflate and gzip compression, thus will compress a single blob of data into another single blob of data.

So, if you're looking for an archive format that can group many files and folders, you need Zip libraries like:

• Xceed Zip (it does support strong encryption)
• SharpZipLib

If you only need to compress and encrypt a single blob of data, then look under System.IO.Compression and System.Security.Cryptography.

Answer 4

The GZipStream class is a native way to handle compression.

As for encryption, there are many ways to do it, most of them in the System.Security namespace. They can be done chained (encrypt a compressed stream or compress an encrypted stream).

Answer 5

Chilkat provides .NET libraries for compression and encryption.

Answer 6

I'm not sure if the steps can be combined, but .NET has good support for basic crypto. Here's an article on it.

Answer 7

If they cannot be combined, do compression first and then encryption. Compressing an already encrypted file will lead to poor compression ratios, because a lot of redundancy is removed.

Answer 8

Here is a useful topic:

Help in creating Zip files from .Net and reading them from Java

System.IO.Packaging namespace gives you useful classes to compress data in zip format and support rights management.

Answer 9

There isn't anything you can use directly in C#, however you can use some libraries from J# to do it for you:

http://msdn.microsoft.com/en-us/magazine/cc164129.aspx

Should do just what you want?

With regards to the encryption, have a look at these links:

http://www.codeproject.com/KB/security/fileencryptdecrypt.aspx

http://www.obviex.com/samples/EncryptionWithSalt.aspx