A dongle is a piece of hardware that attaches to a computer in order to make a piece of secured software run. A dongle in this sense is used as a high-end form of security to prevent the unauthorized copying of software, since making a copy of the hardware itself is much more difficult than simply copying the software. The fairly absurd word seems to have been chosen more or less at random as a placeholder to describe the device when it was first used, and over time it was adopted as the actual name.

The primary use of a dongle today is in very expensive software, usually aimed at a small core market. Very expensive rendering and audio mixing software, for example, often makes use of a dongle to ensure that people don’t pirate the programs – which may cost many thousands of dollars for a single license. Computer Assisted Design (CAD) software is another area in which the use of a dongle is not uncommon.

Although a few software companies have attempted to introduce dongle security with their consumer-oriented software, in every case it has been resisted very strongly by the customers. While specialists such as video editors, audio engineers, and architects are relatively willing to put up with the inconvenience of having an extra piece of hardware to keep track of in order to use their software, the average computer user is simply unwilling to put up with a dongle. As a result, consumer software that has incorporated a dongle has tended to have extremely reduced sales and ultimately to fail, or at least to flounder until the software manufacturer releases a new version without a dongle.

The earliest type of dongle was usually attached via a computer’s serial port. When the software being protected was loaded, it checked for the presence of this hardware device. If it found the hardware device, it loaded; if it didn’t find the dongle, it wouldn’t load. This simple system was fairly open to cracking, since a programmer could fairly easily find the value in the software that indicated whether the hardware was present and simply set it to exist.

Modern dongle technology usually makes use of a computer’s Universal Serial Bus (USB) port, plugging in just like a portable flash drive or other small USB device. Rather than simply checking for the presence of a piece of hardware, the software may send an encrypted request to the dongle for a validation key, which is also encrypted. This means that in order to crack the dongle, one must first crack the encryption. An even more secure form stores encrypted bits of the software on the dongle itself, which the program then calls for when it needs them. This means that even if one were to fool the software into thinking the dongle were present, the software would literally be unable to run, since it would be missing key parts of its code.