Doubtless to say, price is always the first topic. We just use the most popular dongle vendors as an example. HASP is expensive, more than 20 USD level. Sentinel is similar, but 1 or 2 USD less. WIBU ( http://www.WIBU.com ) is almost the same with Sentinel (http://www.SafeNet-Inc.com) . Eutron (http://www.Eutron.com) is 10-20 USD level, and similar with UniKey (http://www.eSecuTech.com). You can get a special offer from dongle vendors if you are a really volume customer.
Interface
There are several types of dongle, LPT, PS/2, Serial, USB and even PCI cards. Based on my experience, USB would be best selection, since 95% computer go along with USB ports.
Support
Since software protection is a job need experience, you should know support is also a part of product. Before you buy it, you should check if the support is really good. Try to get more suggestion from their support engineers. If you think the support is not good, you’d better find an alternative to avoid further problems.
Product quality
It is shown that most dongles are produced in China. But it seems that if the production process is controlled under a better management, the product is better. If it is under to bad management, the product is bad quality. It is recommended to choose an international brand, and be careful with the pure Chinese brand even they are cheap.
Functions
The dongle function can help you to implement the software protection schemes. The most basic function is to read and write. All the dongles have this function. If you want to implement more function, you should consult the support engineer from software dongle vendor. If the dongle only has read/write function, it is not a real dongle, it is only a toy.
Trouble shooting
After you buy dongles and send dongles with your software, you will support the dongle for your customers. If you customer meet any problem, you have to help them to trouble shoot the problem. The most common problem is “Dongle Not Found” problem, i.e. after customer install the driver and insert the dongle, the software still say no dongle found. It is a headache for software dongle vendors. But it seems we find a better solution now,. Entron and UniKey provide so-called “Driverless” dongles, which need not install a driver. It is an HID (human interface device), working like mouse. This kind of dongles provide a better solution than traditional dongles.
Part 5.Conclusion
In this simple paper, we discuss the sensitive topic on software protection, and an overview on dongle protection. I just want to share my experience in this area with other developers. Hope you can enjoy it.