product key generation algorithm.

hi all,

i guess many people instal anti virus software on their computer.

we need to purchase/renew the subscription definition update every year. after paid, they will give me a product key e.g. 8CAFT7TST25ZDCKW563VSUJXX

after input the key, the software will renew the expire date.

e.g. 2006 11/ 19 to 2007 11/19, so i would like to how's the algorithm to generate such key. i think the first criteria is unpredicate

so does it involve any message digestion alogorithm?

any comments will be appreciate, or direction is appreciated.

[578 byte] By [kyhoa] at [2007-10-3 7:47:47]