Algorithm for document codes?!

Hello again. So here is my task. I need some algorithm for my documents code. Something similar to algorithm used in credit cards(http://en.wikipedia.org/wiki/Luhn_algorithm). I could use this one but i need something so i can use error correction too . For correction i will need store some check code for each user. I need this because i want my system could work off-line(for example credit cards are valid when formula for calculation gives out 0).

example: user gives 123456789(his real number is 123456788). I check it vs my algorithm correct and give out: correct is 123456788 and there where mistake in 9 position.

 

Such a script could be used to run a bunch of random numbers and then find only the valid ones; not sure if you'll find anyone supporting a way to reverse engineer credit cards like that.

 

I dont need credit cards i need my word documents number generate like that

 

i think for error correction i could use reed-solom codes but i need algorithm for my code word