TheBlacksheep

As theAnswer introduced rankk last week, I feel it's time to introduce my favourite challenge site, possibly the best one out there: TheBlackSheep at http://www.bright-shadows.net. Most members refer to it using the shortened name: TBS.

At TBS, challengers can compete in almost all major computer-related fields: javascript, exploit, cryptography, steganography, crackits, programming, flash, java applets, logic and information gathering. Also there's a "special" section, consisting of challenges that require a special skillset. And challenges that are completely a waste of time are taken to /dev/null.

With 300+ challenges and counting, TBS is surely the biggest challenge site. You can find almost all aspects of the computer world there, from the first and simplest crypto system - Caesar, to the modern and ultimately strong one - RSA, from text steganos, to image and sound ones, from simple php exploits, to XSS and SQL injection, from Windows cracking, to cracking other systems, like Linux, C64, and Texas Instrument :P And of course, the applet challenges there are the most challenging, but yet very interesting and educational :)

If, for any reason, you missed such a great site, register a new account there and start playing before it's too late! Beginner? No worry, you can learn many things along the way, from the challenges, and the great tutorials both written by TBS members and linked from other security websites.