BlackCiph3r, (otherwise known as Nexon Guard) is the Nexon's proprietary Anti-Cheat program that was fully implemented in the June Update. It was implmented alongside the older Hackshield Pro to provide a 'double layer' protection against hacks. Hackshield Pro was an anti-hack program developed by Ahnlab.
Although it was fully implemented in June, the files for BlackCiph3r were seen in the game's folder as early as April.
Before BlackCiph3r was implemented, Ahnlab's Hackshield Pro was the current Anti-Cheat program that Nexon used to protect Combat Arms against hackers. However, it was proven time and time again, that it was ineffective at preventing hackers. It had many security flaws that allowed hackers to easily bypass the program.
Although BlackCiph3r was able to stop hackers for about a week, hackers were able to bypass BlackCiph3r and again, created trouble in the game matches once again. Hackers proved that BlackCiph3r was almost as ineffective as the previous Hackshield Pro.
Immediately after its implementation, BlackCiph3r caused major lag problems, seen taking up as much as 99% capacity of the CPU. BlackCiph3r was soon temporarily removed.
As of the Content Update on the 25th of August 2011, BlackCiph3r was reimplemented into the Combat Arms game, alongside the Hackshield Pro to have a double layer against hackers.