Cheating in chess can take many forms and has existed almost as long as the game itself. The advent of computers has introduced a new form of cheating into the game. Thanks to the computational power of modern-day computers, a player can use a program to calculate thousands of moves for him or her, and determine the best possible scenario for each move and countermove. These programs are often referred to as “bots,” and can even play the game without any user interaction. In this paper, we describe a methodology aimed at preventing bots from participating in online chess games. The proposed approach is based on the integration of a CAPTCHA protocol into a game scenario, and the subsequent inability of bots to accurately track the game states. This is achieved by rotating the images of the individual chess pieces and adjusting their resolution in an attempt to render them unreadable by a bot. Feedback from users during testing shows that there is minimal impact on their ability to play the game. Players rated the difficulty of reading the pieces on a scale of one to ten, with an average rank of 6.5. However, the average number of moves to adjust to the distorted pieces was only 3.75. This tells us that, although it is difficult to read the pieces at first, it is easy to adjust quickly to the new image. 1. Introduction Chess programs have been designed and implemented on computers since the 1950s. In 1950, Shannon published “Programming a computer for playing chess,” in which he presented a chess computer as possible proof of artificial intelligence . At first, these chess programs were created only to test the waters of what computing could do to enhance the game. However, over the years, programs such as Rybka have become very powerful . In 1997, a computer built by IBM, called Deep Blue, even beat then-world champion Garry Kasparov, marking the first time a computer was able to beat a reigning world champion . Some of the chess programs available today include databases of past games and provide numerous ways for players to learn the game and improve their skills. These aspects are certainly positive; however, there are other forms of computer-assisted chess which are not. While cheating in chess can take many forms and has existed almost as long as the game itself, the advent of computers has introduced a new form of cheating into the game. Robots, or “bots,” are computer programs that can read a chessboard and the pieces, determine the best possible move to make, and either recommend the move to a player or make the move for them . These
S. Gianvecchio, Z. Wu, M. Xie, and H. Wang, “Battle of Botcraft: Fighting bots in online games with human observational proofs,” in Proceedings of the 16th ACM Conference on Computer and Communications Security (CCS '09), pp. 256–268, November 2009.
D. Bethea, R. Cochran, and M. Reite, “Server-Side verification of client behavior in online games,” in Proceedings of the 17th Annual Network and Distributed System Security Symposium of the Internet Society, San Diego, Calif, USA, 2010.