I assume that the serial number will be, at some point, typed by a user. The trouble with this setup is not really about verification time, even in Javascript rather, it is the size of the signature which is a problem. The generator has a private key, which it uses to compute the signatures the checker only knows the corresponding public key. a counter of all serial numbers that you have generated) and a signature over the payload. The cryptographically secure solution is to have signed serial numbers: the serial number is the encoding of some payload (e.g. If this solution does not please you, then you do have a need for security, and this calls for cryptography. Only one of every 1000 numbers will be accepted by the checker. The checker works like this: a serial number is valid if it ends with three zeros. When you want a new serial number, increment your counter by 1000 the new counter value is the serial number. If there is no real need for security, then here is a very fast serial number generator, with a checker: Salt: I don't know whether salt is the right word, but the algorithm should have at least one parameter, whose choice alters the generated keys (so that multiple people can use the same algorithm and needn't fear collisions). And only a small fraction of all the possible keys of a given length are actually valid so it's hard to guess keys. I'm also pretty sure that the keys were all generated algorithmically rather than by hand. If you type it in, the software verifies it algorithmically (by checking whether it fulfills certain properties), rather than looking up a huge database. To clarify: If you buy commercial software, it is sometimes protected with a serial number/a key. Rather, it should be very easy to implement (in javascript) and it should be very fast. The algorithm needn't be cryptographically secure. Those numbers should only account for a small fraction of all the possible numbers of the given length. The generator should only produce serial numbers that pass the test of the checker. I would like to be able to set a salt (and maybe a length).

I need a serial number generator and accompanying checker.

License serial key generator