On 12/29/2009, at 09:09 PM, Markus Spoettl wrote:

>> This *heavily* depends on your algorithm. If you generate a key from the 
>> user’s name and email address, then the probability is equal to 0 that a 
>> legit and a generated serial number will collide.
> 
> Well, you don't use the license data to derive a key from it. No sensible 
> solution does that.

Why not? What speaks against it?

>> The damage of both techniques can be equal. And I don’t know if recommending 
>> a framework to prevent piracy is a good advice at all. I’m not against any 
>> framework, but a self-baked solution would be more unique and require more 
>> effort to crack—under the assumption that you have enough knowledge and time.
> 
> No offense but: Quite the contrary. This is security by obscurity which is a 
> big no-no if you ever want something to be secure. RSA for that matter is 
> well known and reasonably hard. 

I think you misunderstood me a little bit. Security by obscurity is one of the 
worst things that can happen, so I added the prerequisite that you need enough 
knowledge and time. You can also use RSA in your own solution, nothing speaks 
against it.

> I believe you are not appreciating how AquaticPrime (and other asymmetric 
> crypto license systems) work: You (the developer) have 2 keys, one private 
> key which is secret and known only by you, one public key. The public key can 
> only be used to de-crypt the license but not to generate one. You use the 
> private key to create a license.
> 
> You just can't develop a license key generator unless you have the private 
> key. It's not embedded in the application, no one knows it except you.
> 
> Using this system instead of something home-baked has the huge advantage of 
> being reliable and tested for years. Plus, the actual decrypting code doesn't 
> have to be secret (in fact it is not) because the only really valuable 
> information is the private key (which is not embedded in the application).
> 
> That said, AquaticPrime (and I imagine other systems mentioned here) don't 
> provide much help to put the license checking code into your app in a way 
> that makes it difficult to remove. You can make it easy for crackers or more 
> difficult. In the end the license check - no matter how sophisticated - boils 
> down to a check which can fail or succeed. If a cracker finds it, it can be 
> removed.

I understand how asymmetric crypto license systems work, but my point was that 
at the end it doesn’t matter what you use and if people distribute a crack or a 
keygen. I highly appreciate the work of AquaticPrime and other similar 
frameworks, but these kind of frameworks are also a problem. If a cracker 
understands once how AquaticPrime works he will produce cracks for other 
applications which use AquaticPrimie much faster in the future—once you 
understand something everything seems to be easy-peasy.

Rafael
Chief Sucker at Juicy Cocktail
http://www.juicycocktail.com/

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