Zipping was never so easy in .Net. Check out this project on codeplex, http://dotnetzip.codeplex.com/

Here are the features of the DotNetZip Library,
DotNetZip works on PCs with the full .NET Framework, and also runs on mobile devices that use the .NET Compact Framework. Create and read zip files in VB, C#, or any .NET language, or any scripting environment. DotNetZip supports these scenarios:
- an ASP.NET app that dynamically creates ZIP files and allows a browser to download them
- a Windows Service that periodically zips up a directory for backup and archival purposes
- a WPF program that modifyies an existing archive – renaming entries, removing entries from an archive, or adding new entries to an archive
- a Windows Forms app that creates AES-encrypted zip archives for privacy of archived content.
- An administrative script in PowerShell or VBScript that performs backup and archival.
- a WCF service that receives a zip file as an attachment, and dynamically unpacks the zip to a stream for analysis
- creating zip files from stream content, saving to a stream, extracting to a stream, reading from a stream
- creation of self-extracting archives.

Njoy coding

To get MD5 hash in C# use this method. It returns same value AS MD5() function in PHP

        public string GetMD5Hash(string input)
        {
            System.Security.Cryptography.MD5CryptoServiceProvider x = new System.Security.Cryptography.MD5CryptoServiceProvider();
            byte[] bs = System.Text.Encoding.UTF8.GetBytes(input);
            bs = x.ComputeHash(bs);
            System.Text.StringBuilder s = new System.Text.StringBuilder();
            foreach (byte b in bs)
            {
                s.Append(b.ToString("x2").ToLower());
            }
            string password = s.ToString();
            return password;
        }

And this one is in PHP

These both will return the same value