.NET Short Unique Identifier

I need a unique identifier in .NET (cannot use GUID as it is too long for this case).

Do people think that the algorithm used here is a good candidate or do you have any other suggestions?

Solution 1:

This one a good one - http://www.singular.co.nz/blog/archive/2007/12/20/shortguid-a-shorter-and-url-friendly-guid-in-c-sharp.aspx

and also here YouTube-like GUID

You could use Base64:

string base64Guid = Convert.ToBase64String(Guid.NewGuid().ToByteArray());

That generates a string like E1HKfn68Pkms5zsZsvKONw==. Since a GUID is always 128 bits, you can omit the == that you know will always be present at the end and that will give you a 22 character string. This isn't as short as YouTube though.

Solution 2:

I use a similar approach as Dor Cohen's but removing some special characters:

var uid = Regex.Replace(Convert.ToBase64String(Guid.NewGuid().ToByteArray()), "[/+=]", "");     

This will output just alphanumeric characters. The UIDs are not guaranteed to have always the same length. Here is a sample run:

vmKo0zws8k28fR4V4Hgmw 
TKbhS0G2V0KqtpHOU8e6Ug 
rfDi1RdO0aQHTosh9dVvw
3jhCD75fUWjQek8XRmMg 
CQUg1lXIXkWG8KDFy7z6Ow 
bvyxW5aj10OmKA5KMhppw
pIMK8eq5kyvLK67xtsIDg
VX4oljGWpkSQGR2OvGoOQ 
NOHBjUUHv06yIc7EvotRg
iMniAuUG9kiGLwBtBQByfg

Solution 3:

var ticks = new DateTime(2016,1,1).Ticks;
var ans = DateTime.Now.Ticks - ticks;
var uniqueId = ans.ToString("x");

Keep a baseline date (which in this case is 1st Jan 2016) from when you will start generating these ids. This will make your ids smaller.

Generated Number: 3af3c14996e54

Solution 4:

Simple usable package. I use it for temporal request id generator.

https://www.nuget.org/packages/shortid

https://github.com/bolorundurowb/shortid

Uses System.Random

string id = ShortId.Generate();
// id = KXTR_VzGVUoOY

(from the github page)

If you want to control the type of id generated by specifying whether you want numbers, special characters and the length, call the Generate method and pass three parameters, the first a boolean stating whether you want numbers, the second a boolean stating whether you want special characters, the last a number indicating your length preference.

string id = ShortId.Generate(true, false, 12);
// id = VvoCDPazES_w

Solution 5:

As far as I know, just stripping off a part of a GUID isn't guaranteed to be unique - in fact, it's far from being unique.

The shortest thing that I know that guarantees global uniqueness is featured in this blog post by Jeff Atwood. In the linked post, he discusses multiple ways to shorten a GUID, and in the end gets it down to 20 bytes via Ascii85 encoding.

However, if you absolutely need a solution that's no longer than 15 bytes, I'm afraid you have no other choice than to use something which is not guaranteed to be globally unique.