I've seen some serial numbers that have been disclosed on the net and can be used to activate any number of copies of software. How is that possible? Doesn't the software provider check the serial numbers against their database, so that every code can be used limited number of times?

  • No. Because having software that requires activation by calling back to the manufacturer is a pain, so a lot of people actively avoid such software wherever possible. Therefore, most manufacturers don't use such active tracking of serial number usage. – Jules Feb 22 '17 at 14:13
  • 1
    It's unclear what your question is. You already state the answer in your question: no, they don't, otherwise that wouldn't work. – Jörg W Mittag Feb 22 '17 at 15:35

I can think of at least three "unlock code" scenarios used by software I have purchased.

  • Simple/Offline. You are issued an unlock code that is fully portable and there are no online checks. The unblock code can be validated offline; for example. if may have certain bytes that are a checksum on the remaining bytes. This offers only the barest of speedbumps to a pirate. but it does allow the publisher to figure out who gave away their unlock code and pursue legal action. Piracy, of course, is a felony, and using someone else's unlock code in a crime. This technique is used by Beyond Compare.

  • Challenge/Response/Offline. You install the software first, and use it to generate a "challenge" based on a fingerprint of your hardware (CPU serial number, MAC address, sometimes even hard drive serial number). The publisher will issue an unlock code that will only work on computers with the same fingerprint. This technique is used by ImageLine.

  • Online. You are issued a serial number. When you sign on, the system checks to see if your serial number is already active on the network, and shuts you down if it is. First person shooter/deathmatch style games often use this technique.

Sounds like in your case the first type is used, so there is no online check and you can copy and steal unlock codes as much as you want, although by doing so you are committing a crime.

| improve this answer | |

You're assuming that all computers are connected to the Internet. If a computer is stand-alone, or on a private network, it will have no access to the software provider. All it can do is check that the serial number appears valid, based on some secret internal algorithm. If that's the case, the same serial number will work any number of times.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.