A Stroke of Victory [Yeongyu]

Chapter 2

Beomgyu sat hunched over his desk, squeezing a stress ball as he stared at the code in front of him. He had ruled out the possibility of it being encrypted using the monoalphabetic substitution—the Index of Coincidence was too low. At this stage of the competition, an affine cipher was wishful thinking. The code surely involved one of the more complex encryption schemes. He was almost certain it was polyalphabetic. Maybe Vigenère? If so, the Kasiski method suggested that the keyword length would be a multiple of seven.

Well, it was a start.

His laptop chimed, startling him.

"Not now, Ryujin," he grumbled. Of course, she couldn't hear him because he hadn't answered the call. He enjoyed their Skype sessions, but she had a knack for calling him at the worst possible times. He really needed to make some progress on his cryptography challenge. He had managed to break each of the other codes relatively easily, putting him ahead in the competition. And he hoped to decipher the message that night, so he could move on to the next round before the other contestants. Beomgyu opened his web browser and navigated to his favorite Vigenère cracking tool. If he was lucky, he might be able to find the keyword in less than an hour. Of course, there was also the possibility that the key could be fourteen or even twenty-one characters long, or that he wasn't dealing with a Vigenère cipher at all, in which case, he would have to start from scratch.

His mobile phone vibrated with a text message:

Answer my call, Anchovy. I know you're there.

He chuckled at the endearing nickname but silenced the phone and placed it face down on his desk. Returning to the matter at hand, he adjusted the frequency histogram of the letters in the message until they roughly resembled the English alphabet. The best-supported hypothesis for the first letter of the keyword was T.

There were many seven-letter words that started with T. It could also be a foreign word, or one that wasn't a real word at all, but he hoped it was something recognizable.

His computer chimed again. Damn, Ryujin was persistent. If he didn't answer the call, he would end up having to come up with some excuse about where he was and what he was doing. It made no sense to disconnect. Ryujin refused to be ignored.

He answered the call with his usual greeting: "What's up, Golden Button?"

"Hey, Ryujin," he was a bit surprised when he saw her. She usually didn't wear makeup, but that night she was all dolled up, with her long light brown hair flowing loose around her shoulders instead of pulled back into her typical ponytail. He wasn't used to seeing her look so... feminine.

"What are you doing?" she asked. "And don't say homework."

"I'm not doing homework."

"Good. What are you doing?"

"Cryptology."

She groaned. "It's the same thing. It's Saturday night. You should be out having fun."

"I am having fun."

"Sure." She shook her head. "You're sitting in your room, alone, crunching numbers. Sounds like a blast."

"Ryujin..."

"I know, I know. It's your life. But you're a catch. I can't believe you don't have a boyfriend yet. I mean, you're in college. You're supposed to be enjoying your youth. There's plenty of time for serious stuff later."

"I've told you a hundred times. I don't want a boyfriend. What I want is to win this competition and graduate at the top of the class. A boyfriend would only eat into my time."

"That's not the only thing it would eat into."

"You're way more interested in my sex life than I am."