Generate my own Serial for an app

[MacBook MH]

Hi guys,
I created my own app. Now i want to add a serial. How do i generate it with a number for example 123456789 so in crates a combination of 321458679 for example is there any app which would do it? Any suggestions?

Thx

 

[angelwatt]

I'd look up hashes such as MD5 for a starting point.