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AAD5E2E7-AD78-487a-9B37-458B9F1EE897

string shortGuid = Convert.ToBase64String(Guid.NewGuid().ToByteArray())
            .Substring(0, 22)
            .Replace("/", "_")
            .Replace("+", "-");

b14I850fIE6cuyv7VnP6WA

public static class GuidExtensions
{
    /// <summary>Get a 22-character, case-sensitive GUID as a string.</summary>
    public static string ToShortString(this Guid guid)
    {
        return Convert.ToBase64String(guid.ToByteArray())
            .Substring(0, 22)
            .Replace("/", "_")
            .Replace("+", "-");
    }
}

string shortGuid = Guid.NewGuid().ToShortString();

string shortGuid = new ShortGuid(Guid.NewGuid());

Guid regularGuid = ShortGuid.Parse(shortGuid);

Guid regularGuid = Guid.NewGuid();
string shortGuid = new ShortGuid(regularGuid);
 
// Writes "True"
Console.WriteLine(regularGuid == ShortGuid.Parse(shortGuid));

public class ShortGuid
{
    private readonly Guid guid;
    private readonly string value;
 
    /// <summary>Create a 22-character case-sensitive short GUID.</summary>
    public ShortGuid(Guid guid)
    {
        if (guid == null)
        {
            throw new ArgumentNullException("guid");
        }
 
        this.guid = guid;
        this.value = Convert.ToBase64String(guid.ToByteArray())
            .Substring(0, 22)
            .Replace("/", "_")
            .Replace("+", "-");
    }
 
    /// <summary>Get the short GUID as a string.</summary>
    public override string ToString()
    {
        return this.value;
    }
 
    /// <summary>Get the Guid object from which the short GUID was created.</summary>
    public Guid ToGuid()
    {
        return this.guid;
    }
 
    /// <summary>Get a short GUID as a Guid object.</summary>
    /// <exception cref="System.ArgumentNullException"></exception>
    /// <exception cref="System.FormatException"></exception>
    public static ShortGuid Parse(string shortGuid)
    {
        if (shortGuid == null)
        {
            throw new ArgumentNullException("shortGuid");
        }
        else if (shortGuid.Length != 22)
        {
            throw new FormatException("Input string was not in a correct format.");
        }
 
        return new ShortGuid(new Guid(Convert.FromBase64String
            (shortGuid.Replace("_", "/").Replace("-", "+") + "==")));
    }
 
    public static implicit operator String(ShortGuid guid)
    {
        return guid.ToString();
    }
 
    public static implicit operator Guid(ShortGuid shortGuid)
    {
        return shortGuid.guid;
    }
}