If he wanted to brute force it, then he would need a day or two for himself. With the looming Gate 10, however, he couldn’t afford to do that. Marta and William needed to get stronger. They needed him.
’I don’t need a computer to do Caesar ciphers or Vigenère ciphers. It’s simple. But this is different. There’s Arabic lettering included and Surian—’
"You’re distracted," Sun-young stated, snapping him from his thoughts. "Is sothing wrong?"
He blasted her with a hundred-watt smile. "Oh, it’s nothing."
His smile almost convinced her not to follow up. In fact, in the past, she wouldn’t have.
"Is it?"
So what changed? She was asking. She was showing her worry.
Kazi didn’t want to lie to her, especially considering that there was no reason to. "It’s complicated," he admitted. "Do you know what cipher coding is?"
A slow shake. "No."
Okay, that complicated things. "Do you really want to know?"
"Is it math related?"
"Yes."
"I’ve been to the Sky," she said. "I think I can handle it."
Ah, right, the Suneung—the Korean college exam—was notorious for its difficulty. If there was anyone that was capable of understanding cipher coding, it was Sun-young, soone that passed the exam with flying colours and made it to one of the three most prestigious universities.
"Okay, so imagine you have a secret ssage you want to send to a friend, but you don’t want anyone else to understand it if they happen to see it. So, instead of writing the ssage as it is, you decide to mix up the letters or use a special code to hide what it says. Let’s use the Caesar cipher. This code involves shifting each letter of the alphabet by a certain number of places. So, if ’A’ becos ’D’ because you shift it three places, your ssage might look like random letters to soone who doesn’t know the secret shift. So, if your original ssage was ’HELLO,’ in a Caesar cipher with a shift of three, it will beco ’KHOOR.’ To decode it, your friend would need to know that the letters were shifted by three places to get the original ssage. There are many other types of codes too, like substituting letters with symbols or using keywords to encode ssages. Each one has its own way of hiding the ssage and requires a key or thod to decode it back to the original text."
"I’m following," Sun-young said.
"Cool. So rember my fight with William? When, you know, he was going crazy? During our fight, I fell into another dinsion, similar to the one where we encountered the Wendigo. There were codes in the skies. Numbers, letters, that sort of thing. There’s no internet in this world so I have to manually put the code in my brain and encrypt it."
"So what was the arrangent?"
"Uhh...it’s kinda long."
"Go for it."
"As in, it would take seven hours to say it all."
"Oh. Okay." Pause, blink, and a scrunch of her eyes. "Wait, when you ant the sky...you an the sky?" She pointed at the blue skies of this world. Kazi nodded. "You morized all of it?"
"Photographic mory cos in handy," Kazi said, shrugging. "It’s why I specialize in linguistics. And textiles. And dicine. And architecture. And hardware. And cars. And city infrastructure. And, well, a lot of things actually."
"Including cipher coding?"
"I worked for my governnt once. A short contract where I did a lot of data encryption. One person alone can’t do much but with a computer, so leadership, and enough experienced people, you can accomplish a lot. In my brief ti there, I figured out a way to decipher RSA encryption. RSA encryption relies on the difficulty of factoring large pri numbers. The trick isn’t about finding the pris themselves, but it’s about deriving the private key from two very large pris. They use modular arithtic and exponentiation to encrypt and decrypt ssages. The thod involves picking two distinct pri numbers, multiplying them to obtain the public key, and deriving the private key from the pris’ factors. The challenge lies in the sheer difficulty of factoring the product of two large pris. But, in my case, I realized that the encryption process leaves so residual patterns in the ciphertext long-term."
Sun-young bobbed her head along. "I see."
"So, with the help of the governnt computer scientists, great guys by the way, we wrote an algorithm that detected patterns in the way the encryption altered certain blocks of data. These minute alterations can lead to partial information about the pris used, enough to narrow down the potential range of factors significantly. There’s still a lot of brute forcing involved but it turned RSA decrypting from impossible to possible."
"I get it. Abstract algebra, and knowledge of pris and multiplicative groups."
"So statistics too."
"Like entropy?" When Kazi nodded, Sun-young humd. "Discrete mathematics to create ciphers and statistics to break them. Am I getting this right?"
"Yeah, yeah, exactly!"
Sun-young understood. Of course she did, she was well-educated and well-versed in language arts, math, English, and law. It wasn’t until he got into the nitty-gritty that his explanations started to wear her down.
For the first fifteen minutes, everything was okay. Kazi was able to talk with a smile. Bit by bit, as the conversation got more complicated, his smile faded. Sun-young was failing to understand. Even as he did his best to explain in simple terms, she had no idea what he was talking about and awkwardly nodded her head along.
"I think I get it," Sun-young said, though her tone suggested otherwise.
Kazi chuckled softly, deciding to end it with a joke. "You know, there’s a joke among cryptographers: Why do we always get invited to parties? Because we’re really good at keeping secrets!"
Blank face. She did not find that funny in the slightest.
Kazi smiled again, though it was a bit more subdued. "Ahem, anyway, you should get back to ditating. Maybe next ti we can talk about sothing less cryptic!"
Eh?
Eh?
Another attempt at a joke. Sun-young’s smile returned, albeit a bit strained. "Sure."
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