Mentor Graphics is using flexlm to protect their products. Are they using any special flexlm protection cause I can't seem to use their products just by getting the usual encryption seeds.

The daemon's name is mgcld.

They check the vendor string using a proprietary checksum
algorithm. If you get the message "FATAL CS ERROR" it's because
you don't have the checksum correct.

So, is this a kind of vendor defined checkout filter implementation, that is if I follow Amante's essay on this particular topic - I should be able to reverse this product ??

Or, as you say - proprietary checksum algorithm which means following that essay is not sufficient to simply reverse the product ?

Which comes to the next question - how do I go about tackling this kind of protection scheme - any ideas ??

Well, it's not all that tough a protection - basically certain
information such as the start date, number of licenses, expiry, and feature name are combined.
This is run through a checksum routine, and
the value compared against one one supplied
in the vendor_string.

So it's not too hard, and much easier than many shareware
protections.

--nb

Could you give me any idea about how to find checksum routine?
I've spent about a day in trying to find a place, where checksum is checked, but nothing...

PS: I'm trying to reverse QuestaSim 6.1c

Did you bother to look at the DATE on this Post????? Why do you expect someone to come back and answer a question from more then 5 years ago?

Regards,

I thought, that adding message to this thread is better, than starting new one.
Yes, I seen date of last post, but this topic still actual, cause there are new versions of mgcld.



One man come back and tried to answer my questions in private.
Quite good result of my post.

PS: If you think, that I should start new thread to discuss my problems with mgcld, I'll start new one.

The "Point" of my comment is that you actually asked a question of "Nolan Blender" who (unfortunately) hasn't actually posted a response here in quite some time. You did not phrase your question to the "general public," but to "Nolan Blender" specifically.

In such circumstances it would have been better to have started a new Thread and to state you had searched the Forums and reviewed the Posts and had not found an answer to your question. But since you have already re-opened this ancient Thread, it might as well remain here.

Regards,