The Genius Cryptographer

“KEITH is never a straight A student, in fact, he’s grade rank used to stay at the bottom of the 56 students in the class. His math may not be good, at school, but his math is really good in practice.

Kids in China used to buy redemption cards to top up their online game account, KEITH was not an exception, he loved video games.

In a Saturday afternoon, when KEITH’s dad was at home, after competing gunshot with money betted, they needed to decided something to do to kill this boring afternoon. Somehow, they decided to play math.

Little KEITH when downstairs to the vendor machine, he bought four QQ coin (Tencent) redemption cards with continuous card number. Then they started trying to figure out the function of the passcode which is randomly generated.

Surprisedly, it did not take them too long. After two or three hours struggling, they came out with a conclusion: the code was positive generated with arithmetic progression in hexadecimal after reverse alphabet to numbers.

KEITH successfully redeemed two cards, and later was stopped by his father due to ethical code.