A hush fell over the room as everyone turned their attention to the young man standing before them. Lin Yun, barely out of high school, was about to lecture some of the brightest minds in the country on cryptography, a field they themselves were just beginning to explore.
Lin Yun took a deep breath, a slight tremor of nerves running through him. Even though he had no problem giving a speech in public, this was different. These weren't students or employees, but seasoned researchers and scientists, their eyes filled with curiosity and skepticism.
"I know what you're thinking," Lin Yun began with a smile. "What can a kid like me possibly teach you about cryptography?"
A few chuckles rippled through the audience, easing the tension.
"Well," Lin Yun continued, his voice gaining confidence, "I'm here to share some insights that I came up with. But first, let's recap the basics."
He turned towards the whiteboard and picked up a marker. With practiced ease, he began outlining the fundamentals of cryptography, starting with the simplest concepts.
"One-key cryptography," he announced, writing the words in bold letters. "Also known as symmetric encryption. It's the most basic form of cryptography, where the same key is used for both encryption and decryption."
He explained the concept in simple terms, drawing diagrams and providing examples. He then moved on to more complex algorithms, like DES and Triple DES, outlining their strengths and weaknesses.
"DES, or Data Encryption Standard," he explained, "was once the gold standard. But with advancements in computing power, it's become vulnerable to brute-force attacks."
He then delved into Triple DES, a more secure variant of DES, explaining how it addressed some of the weaknesses of its predecessor.
"Triple DES," he said, "essentially applies the DES algorithm three times, making it much more robust. But it comes at a cost—it's significantly slower."
Lin Yun paused, taking a sip of water. He could see the audience was fully engaged, their eyes glued to him, their expressions a mixture of concentration and intrigue.
"Now," he continued, his voice gaining a hint of excitement, "let's talk about RSA."
He wrote the acronym on the board, explaining its significance. "RSA, or Rivest-Shamir-Adleman, is a public-key cryptosystem. It's widely used for secure data transmission."
He delved into the intricacies of RSA, explaining the concept of public and private keys and how they were used to encrypt and decrypt data.
"RSA," he emphasized, "is a revolutionary algorithm. It's based on the practical difficulty of factoring the product of two large prime numbers. This makes it extremely secure, even against brute-force attacks."
Lin Yun could see the admiration in the eyes of the audience. RSA was indeed a groundbreaking algorithm, a testament to human ingenuity.
"But," he continued, a mischievous glint in his eyes, "even RSA has its limitations."
He paused for dramatic effect, letting his words sink in.
"It's computationally intensive," he explained. "This makes it less suitable for applications that require high-speed encryption and decryption."
He then turned towards the audience, his gaze sweeping across the faces.
"And that," he announced, "is where AES comes in."
A wave of murmurs washed over the audience. AES, the Advanced Encryption Standard, was a name completely foreign to them. In this world, everyone was still grappling with the limitations of DES and RSA; the concept of AES was a revelation. It was as if Lin Yun had pulled it out of thin air, a cryptographic marvel that had never existed before.
Lin Yun, sensing their curiosity, calmly continued. "AES," he began, his voice steady and measured, "is a symmetric-key algorithm. It's a completely new cipher I developed, designed to be both incredibly secure and remarkably fast."
He turned back to the whiteboard, his marker gliding across the surface as he began to illustrate the structure of AES. He explained the concept of a substitution-permutation network, the intricate layers of transformations that scrambled the data into an indecipherable mess.
"Unlike DES, which operates on blocks of 64 bits," Lin Yun explained, "AES uses a larger block size of 128 bits. This, combined with a sophisticated key schedule, makes it significantly more resistant to brute-force attacks."
He then delved into the key lengths supported by AES, explaining how the algorithm could accommodate keys of 128, 192, and even 256 bits.
"The longer the key," he emphasized, "the stronger the encryption. With a 256-bit key, AES is practically unbreakable, even with the most powerful computers imaginable."
Lin Yun could see the awe in the eyes of the audience. He had presented them with an algorithm that seemed to defy the limitations of their current understanding of cryptography. It was a testament to his genius, his ability to conceive and develop such a complex and powerful cipher.
He then moved on to the various modes of operation supported by AES, explaining how the algorithm could be adapted to different applications.
"For example," he said, "Cipher Block Chaining, or CBC, is ideal for encrypting large amounts of data, while Counter mode, or CTR, is better suited for streaming applications."
Lin Yun's explanation was clear and concise, devoid of any arrogance. He was simply sharing his knowledge, guiding them through the intricacies of this revolutionary algorithm.
He then proceeded to demonstrate the efficiency of AES, comparing its performance to DES and Triple DES.
"As you can see," he said, pointing to a graph on the whiteboard, "AES is significantly faster than its predecessors, especially when dealing with large amounts of data."
This was a crucial advantage, especially in a world where internet speeds were steadily increasing and the demand for secure data transmission was growing exponentially.
Lin Yun concluded his explanation of AES with a simple statement. "This algorithm," he said, "represents a significant leap forward in cryptography. It's the most secure and efficient algorithm we have today."
Lin Yun smiled inwardly. He had long surpassed the state of having a guilty conscience by taking these existing inventions from Earth. Even though he wasn't the person who invented AES, in this world, he was destined to be an inventor.
In the future, there would be more and more technology coming out, and he couldn't just feel bad about "copying" it every time…