Custom Guid’s

Caught a question from Stacy Draper, @StacyDraper this morning about custom guids, to make them more recognizable.

It reminded me of a post I saw recently about Facebook using hex characters to make IPv6 addresses more recognizable.

Here’s what I was thinking… create a guid that has an embedded word.

For example, the following code creates a Guid that always starts with FACEB00C:

using System;

usingSystem.Collections.Generic;
using System.Linq;
usingSystem.Text;

namespaceCustomGuidTest
{
    class Program
    {
        static void Main(string[] args)
        {
            GuidcustomGuid = GenerateCustomGuid();
            Console.WriteLine(customGuid.ToString(“B”));
            Console.ReadKey();
        }

        static Guid GenerateCustomGuid()
        {
            Guidresult;

            //0xFACEB00C
            //backwards, but required this to achieve desired result

//Likely due to some standard with respect to bit order.
byte[] custom = new byte[] { 0x0C, 0xB0, 0xCE, 0xFA };

            byte[] random = Guid.NewGuid().ToByteArray();
            byte[] final = new byte[16];
            for(int idx = 0; idx <16; idx++)
            {
                if(idx >= custom.Length)
                {
                    final[idx] = random[idx];
                }
                else
                {
                    final[idx] = custom[idx];
                }
            }
            result = newGuid(final);
            returnresult;
        }
    }
}

Example output:
{faceb00c-7828-4e99-8cf5-280e33202670}

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Published by Jim Wilcox (The Granite State Hacker)

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