DUID: The high entropy, web-friendly, globally unique identifier

DUID is a fully-featured replacement for GUIDs (Globally Unique Identifiers). They are more compact, web-friendly, and provide more entropy than GUIDs. I created this UUID type as a replacement for GUIDs in my projects, improving on several GUID shortcomings.

I pronounce it doo-id, but it can also be pronounced like dude, which is by design :)

Key security features:

• Uses the latest .NET cryptographic random number generator
• More entropy than GUID v4 (128 bits vs 122 bits)
• No embedded timestamp (reduces predictability and improves strength)
• Self-contained; does not use any packages

Usage features:

• High performance, with minimal allocations
• 16 bytes in size; 22 characters as a string
• Always starts with a letter (can be used as-is for programming language variable names)
• URL-safe
• Can be validated, parsed, and compared
• Can be created from and converted to byte arrays
• UTF-8 encoding support
• JSON serialization support
• TypeConverter support
• Debug support (displays as string in debugger)

Nuget

Yes, you can also find DUID on nuget. Look for the package named argentini.duid.

Usage

Similar to Guid.NewGuid(), you can generate a new DUID by calling the static NewDuid method:

var duid = Duid.NewDuid();

This will produce a new DUID, for example: aZ3x9Kf8LmN2QvW1YbXcDe.

There are a ton of overloads and extension methods for converting, validating, parsing, and comparing DUIDs. Here are some examples:

// Represents an empty DUID (all zeros); "AAAAAAAAAAAAAAAAAAAAAA"
var emptyDuid = Duid.Empty;

// Get a string value for a DUID
var duid = Duid.NewDuid();
var duidString = duid.ToString();

if (Duid.TryParse("aZ3x9Kf8LmN2QvW1YbXcDe", out var duid)
{
    // Successfully parsed DUID
}

if (Duid.IsValidString("aZ3x9Kf8LmN2QvW1YbXcDe"))
{
    // Successfully validated
}

if (duid1 == duid2)
{
    // Comparison works as expected
}

There is also a JSON converter for System.Text.Json that provides seamless serialization and deserialization of DUIDs:

var options = new JsonSerializerOptions();
options.Converters.Add(new DuidJsonConverter());

var user = new User
{
    Id = Duid.NewDuid(),
    FirstName = "Turd",
    LastName = "Ferguson"
};

var json = JsonSerializer.Serialize(user, options);

/*
    json =
    {
        id: "xw5x7Kf6LmN3QvW1YbXcc0",
        firstName: "Turd",
        lastName: "Ferguson"
    }
*/

Dapper data type handler

Here's an example of adding DUID support to Dapper, where we convert DUIDs to strings and back again in a Postgres database.

First, add the handler to your project:

using System.Data;
using Dapper;

namespace MyApp.Api.Extensions;

/// <summary>
/// Handles mapping between Duid and database types for Dapper.
/// </summary>
public sealed class DuidTypeHandler : SqlMapper.TypeHandler<Duid>
{
    public override void SetValue(IDbDataParameter parameter, Duid value)
    {
        parameter.Value = value.ToString();
    }

    public override Duid Parse(object value)
    {
        return value switch
        {
            string s => Duid.Parse(s),
            _ => throw new DataException($"Cannot convert {value.GetType().Name} to Duid")
        };
    }
}

Then add the type handler near the top of your Program.cs file, before Dapper is used.

...

var builder = WebApplication.CreateBuilder(args);

SqlMapper.AddTypeHandler(new DuidTypeHandler());

...

This scratches the surface of what's available. Try using DUIDs in your project to explore all the features it provides.