Need unique case ID field

Need unique case ID field

If I use the auto number field, it is hidden and the user cannot see the field to use that as a case id.  Due to confidentiality requirements, using the victim name is not an option.  

I am assuming I will have to use a single text with no duplicate entries.  But, this means the users will have to generate their own case ids.

Is there a better way to insure compliance and consistency?

I would really like to keep my current method, ##-####-####  
first two digits, member program service provider id
middle four digits, computer generated unique case id
last four digits, year of data entry