ÜberUtils - Part 1 : Cryptography

ÜberUtils Series posts so far :

• Part 1 : Cryptography - Hashing
• Part 2 : Cryptography (Continued) - Encryption
  
• Part 3 : Strings
• Part 4 : Collections

If you read my previous post, you would know that it is my time to give back to the community. So where should you start when creating the ULTIMATE REUSABLE UTILS CLASS LIBRARY? (from now on called ÜberUtils)? Good question, and thats the reason why its taken me a while to start this series, cause I had to start it at exactly the right point. I thought back to the first utils class I wrote back in 2003 in .NET 1.1. It was a cryptography class that wrapped existing functionality that exists in the system.security.cryptography namespace.
So I figure thats a good place to start again. But first I wanna note a few things :

• This code will be written for .NET 3.5 framework (this is to take advantage of the newer features)
  
• I will be using VS2008 beta 2 which, which at this point in time (Oct 2007), you can download for free. (I want to utilise some of the new features available e.g. Unit Testing)
• The namespaces I use will be as simple and generic as possible, meaning that it will be simple to incorporate into any number of companies / projects / systems / architectures etc. I hate having weird long namespaces when I use other developers libraries. I would prefer a namespace like "Utils" rather than "BradVin.Core.Utils". Wouldnt you agree? (I was also thinking about using "System.Utils")
  
• The project files and code can be downloaded from codeplex at the ÜberUtils project page.
• Code license : public domain. This means that all the code in this series is absolutely free, and by definition : the code may be freely reproduced, distributed, transmitted, used, modified, built upon, or otherwise exploited by anyone for any purpose, commercial or non-commercial, and in any way, including by methods that have not yet been invented or conceived. So rip it to pieces, pull out what you like - I DONT CARE! My only stipulation is this : IF YOU ADD SOMETHING USEFUL PLEASE SHARE IT WITH US!!!!! (you can do this by commenting on this blog or on discussing it at code plex)
  

I'm gonna start with a Hashing class which is extremely simple to use. This class makes it easy to hash a byte array or a string e.g.

string strHash = Hashing.Hash("test");

You can also use different hashing algorithms e.g.

string strHash = Hashing.Hash("test", Hashing.HashingTypes.SHA512);

Internally, the different hashing algorithm classes used are : SHA1CryptoServiceProvider, SHA256Managed, SHA384Managed, SHA512Managed and the default MD5CryptoServiceProvider.

Very simple isn't it?. Here is the class diagram :

If you have a look at the code, you would have noticed some strange new methods on both string and byte array. This is using a new .NET 3.5 feature called extension methods. If you've not heard of it yet, the best explanation is by ScottGu here. Infinities Loop also talks about it here and ScottGu again here . So let's see how I implement my extension methods. Check this code out :

private string ComputeHash(string inputText)
{
     //convert output byte array to a string
     return ComputeHash(inputText.ToByteArray()).ToHexString().ToUpper();
}

namespace Utils.Extensions
{
    public static class ByteArrays
    {
        public static string ToHexString(this byte[] data)
        {
            StringBuilder sb = new StringBuilder(data.Length * 2);
            foreach (byte b in data)
            {
                sb.AppendFormat("{0:x2}", b);
            }
            return sb.ToString();
        }
        public static byte[] ToByteArray(this string str)
        {
            return ASCIIEncoding.ASCII.GetBytes(str);
        }
    }
}

Now all I had to do to use these methods was add a using at the top of my class :

using Utils.Extensions;

But I didn't want to just stop here. I've had a scenario in the past when I needed to compute a MD5 hash of a string. I also found this blog post on the subject and decided I can now use extension methods to add this functionality to every string. So heres the code :

namespace Utils.Extensions
{
    public static class Cryptography
    {
        public static string GetMD5HashCode(this string str)
        {
            return Utils.Cryptography.Hashing.Hash(str);
        }
    }
}

So now I can use it on any string e.g.

string actual = "test".GetMD5HashCode();