The Coloured Barcode - Chapter 3 (Short story)

The group study session was in one of the study areas. Half the class was there already, as well as a few fourth years. Cassie's classmates, the third years, were busy studying. That was to be expected, as a lot of them were a bit stuck on a lot of things that would be in the exam. The fourth years, by the looks of it, were goofing off. The conversation about the advantages and disadvantages of MCQs with negative marking.

"Oh hello Cassie! did you already do these two problems?" asked Anna.

Cassie blinked twice. She had not seen those two particular questions in her life. Anna understood this right away.

"Nevermind, do it now. Lex, you told us you'll teach us about this."

"Hand me the book," said Cassie. It would be good practice if nothing else.

Lex, one of the fourth-years, sighed. "I already taught you this. Look, if you're that overworked, work on your project or something. It's due with the exam, right?"

"No, two days afterwards, plus it's not the same subject," said Jake, one of Cassie’s classmates.

Cassie jumped. "But I already submitted it! The deadline is tomorrow and I didn't want..."

"We got an extension," said Jake.

“You traitor! Why didn’t you tell me?”

Jake shrugged. “It wouldn’t matter to you anyway. What were going to do, run it through a spell check for a fiftieth time?”

Cassie bit back a retort. She could have checked her calculations again and maybe polished the conclusion.

"Wait, about the project, how did you wire the seven-segment display? Four digits is impossible, right?" asked Anna.

"Forget the project - we'll tackle that when we have to," said Jake, "First, Cassie, can you solve this?"

Cassie gave him her best death glare - she was working on the two problems that Anna gave her earlier. She was kept quite busy for some time, solving question after question. As expected, her friends pointed out things that she had almost overlooked. She had no time to think of the cipher, let alone work on it. 

The rest of the class also joined them one by one. Anna was forced to shut up about the project for the time being. The fourth years helped as well - they had an exam the next day, but apparently, it was easy, so they had time to spare.

Finally, they decided to break for dinner. As they got up, Anna turned to Cassie.

"Really, Cassie, how did you wire the seven-segment display?"

"Huh? Did you switch the anode or the cathode?"

"What's the anode and what's the cathode? Which one is connected to which number? Look, explain it to me over dinner. Please? Don't tell me to look it up on the internet - I tried, I honestly tried..."

Cassie rolled her eyes. "Of course you did. Get me a paper and a pen."

Cassie sketched it on the paper. She explained it as quickly as she could. Then she returned to her bag to pack her things. That was when she noticed the slip of paper containing the cipher in her bag. She pulled it out again and looked at what she had decoded.

01236 10643 50263 46310 056432 12 2165 36201 52036 10346 246530 325062 5126 63012 12 21 60431 50236 21 02356 

It was definitely base 7. The seven-segment display was essentially seven digits, aka, base seven. This was too good to be a coincidence. She looked at the first entry - 01236. It was not repeated as is, but the same numbers, 0, 1, 2, 3, and 6, were present three times in the code. Not one entry had duplicate numbers. Her theory could be right. She took a piece of paper, and sketched the result, with the numbers 0-6 representing the segments a-g of a seven-segment display.

 Cassie sketched the first digit. It was the segment on top, then the one on the top right, then the bottom right, then the bottom segment, and finally, the middle segment. What emerged was, unmistakably, a 3.

That was better than nothing, but what was a number supposed to mean? She moved on to the next digit. Slowly, a set of numbers emerged.

What Cassie noticed, instantly, was that the numbers were 1-6. Now there were six numbers instead of seven, she was back to where she started. She couldn't think of anything it could possibly mean. This set of numbers had to be the result – this cipher was incredibly inefficient in terms of the number of characters it took to represent a single digit. 

There were twenty digits – too much for a credit card number, even with the security code attached. If one number was a dummy, it was a possibility, but you’d have to know which number the dummy was. There were too many digits for it to be an account number. Perhaps it was an account number followed by a transaction code or amount.

But would any of them use just 0-6? That would be an insane coincidence.

It could also be a password. She didn't know the admin password in the department's computer labs, but this might be it. But then again, she thought, it was unsafe and ridiculously difficult to remember. It could also be the serial number of a SIM, but why would you even bother sending it to someone in such an obvious cipher? What could you use it for in the first place?

She could go dumpster diving again and find more papers written in the same code, but it was likely too late to do that now. She returned to the study room, still thinking about it.

As she settled down, Anna entered the room. She sat down next to Cassie and picked up a book. Cassie looked at her. She was rifling through the textbook with no real aim in mind. She decided to ask Anna.

"Anna, what kind of number has 20 digits?"

Anna looked at Cassie like she had grown another head. "Come again?"

"What king of number has twenty digits?"

"pi to twenty digits? I know only 3.14 though."

"Seriously, I meant a number that can actually mean something to someone. Our student ID is 8 digits, for example. What kind of number has 20 digits?"

"20 consecutive tosses of a die?" asked Anna.

It took a few seconds for that to sink in. That was it! It was the results from some gambling operation. It was probably run by some students. Then again, she deleted that thought immediately. No one would trust a gambling ring where the results were based on the result of a die if they didn't witness someone tossing the aforementioned die. If they were present, chances were, they'd write it down or take a video of it.

"Cassie, are you aright? I thought you were happy for a second, and then, immediately, you were like, oh, I'm out of battery, where is my charging port. Are your circuits actually fried?"

"Anna, I swear, if you call me a robot one more time, I will toss you out of that window over there."

"That's like, a metre off the ground."

"I'm not trying to murder you. I'm simply trying to be in a different room."

"What are you two arguing about?"

That was one of the fourth years, Bella.

"Cassie wants to know what a twenty-digit number could be," supplied Anna.

"A password created by a robot, a twenty-digit prime number used for encryption, like a key, but then 20 numerical digits is way too short," said Bella, "why?"

"Answers to an MCQ with 20 questions. Or would it be a, b, c, and d? Technically you could convert it to numbers." It sounded like a disembodied voice that sounded remarkably like one of their classmates, Jake. On closer inspection, it appeared to come from behind the bags.

"Yeah, then the numbers would have to be zero to four," said Cassie.

"Then show us the thing you're talking about," said Bella, "you obviously have a specific twenty-digit number in mind."

Anna was a simple airhead, Jake was a prankster, and Bella was a fairly normal nerd. None of them could be involved with the creation of a potentially criminal document. She showed them the paper.

"Hold on, I've seen these numbers before," said Bella, "I can't remember where, really, wait, what did you say, Jake, some time ago?"

"I have been silent for the past..." started Jake but was interrupted by Bella.

"MCQ! It's the answers for the freaking Econ MCQ! Where on earth did you find this, Cassie?"

"MCQ? Wait, what? It's not criminal? Are you sure?"

Anna chimed in. “Wait, you have six answers in an MCQ?”

Bella ignored her. "Where did you find it? Cassie, this could be serious. This could be serious academic misconduct. Where did you find it?"

"I - uh, I have a photo, give me a minute," said Cassie, quickly pulling it up on her phone. 

Was it just MCQ answers? No, that was not possible. She did not pour so much of her heart and soul into finding the answers to an MCQ. It was supposed to be something criminal. True, it was written on the back of a set of printed slides, which in hindsight, looked like econ notes. On the other hand, econ notes didn’t make something not criminal. There was hope yet.

"I knew it!" said Bella, "this is an econ note alright. Wait, where was this written?"

Cassie explained how she broke the code to her. Cassie's head was in a whirl. This could not be. As she was explaining this, Lex walked in. He listened in silence until the explanation finished.

"You actually broke the code? I thought that impossible. That's precisely why I threw it in the bin."

Bella turned and glared at him. Cassie’s heart sank. There was no way Lex would do anything criminal.

"Let me guess. You finished what you could of the paper, you were bored, you didn't want to submit the paper as it was, so you created a cipher just because you could to buy time to go over the paper with a fresh perspective before you handed it in," said Cassie.

"Great deduction," said Lex, "Well, done, detective Cassie."

Cassie blushed. Maybe it was worth it after all.

"Why, thank you!"

 

This is the final installment of this particular story. I hope you enjoyed it. Stay tuned for more of Cassie's adventures (hijinks?).

You can read Chapter 1 here and chapter 2 here.

This is the second edition of the story, the first is on Wattpad :)

You can also follow me on Facebook here.

Until next time!