Algorithm for unique CD-KEY generation with validation

Question

I am trying to create a unique CD-KEY to put in our product\'s box, just like a normal CD-KEY found in standard software boxes that users use to register the product.

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Answer 1

I finally settled for a cd-key of this form

<TIMESTAMP>-<incremented number>-<8 char MD5 hash>-<checksumdigit>

I used the mod 11 ISBN checksum digit algorithm.

Answer 2

I use SeriousBit Ellipter link for software protection but I don't see any reason you could generate a group of unique keys each week and us the library to verify the key validity when entered into your web site. You can also encode optional services into the key allow you to control how the sample is processed from the key (that's if you have different service levels).

As it uses an encrypted method of key generation in the first place and it's relatively cheap, it's certainly worth a look I would say.

Answer 3

Create the strings <providername>000001, <providername>000002, etc. or whatever and encrypt them with a public key, and that's your "CD-KEY" that the user enters. Decrypt the CD-KEY with the private key and validate that when decrypted you get a valid string with a valid provider name.

Answer 4

Generate GUID and catenate a random number to it. GUID is guaranteed to be unique and random number will make it improbable to hit a code accidentally. Just don't modify the GUID in any way or you might compromise the uniqueness.

http://msdn.microsoft.com/en-us/library/aa475087.aspx

Answer 5

Credit Card numbers use the Luhn algorithm you might want to look at something similar to that.