Assignment Question

I’m working on a cyber security discussion question and need the explanation and answer to help me learn. Hello everyone, Took me a little bit to get this simple yet at first a bit complex for me to comprehend. Hurting my lower back at the start of class did not help…. Smh! Using the Vigenère cipher table Hard work always pays using the key ORANGE is VRRQ CSFB AYCEMJ PNEW Using the same key for Oktnio ok dncr gave me ATTACK AT DAWN. An Italian cryptographer named Giovan Battista Bellaso developed the Vigenere Cipher in 1553. Nevertheless, Blaise de Vigenere, a French cryptographer from the 16th century, was wrongly credited with inventing a similar cipher in 1586. Despite the fact that the confusion was subsequently resolved, the name Vigenere became the cipher’s official title. The Vigenere Cipher is a substitution cipher that encrypts or decrypts communications using a code key and the Vigenere table. The alphabet is displayed in 26 rows and columns of the table. The alphabet is printed in standard order in the first row, but each subsequent row sees a one-position shift to the left of the alphabet (Simmons, 2023). For a while, the Vigenere Cipher was thought to be unbreakable and was even dubbed “the unbreakable cipher.” But in 1863, Friedrich Wilhem Kasiski and Charles Babbage succeeded in cracking the cipher. The Kasiski Test is the technique used to crack this cipher. According to Kasiski, this cypher’s primary flaw is the key word’s repetition in conjunction with the message. It was found that they could break the encryption by using frequency analysis, which is also used to break Caesar ciphers, to determine the length of the keyword (Clark, 2020). References: Simmons, G. (2023). Vigenere Cipher. Britannica. https://www.britannica.com/topic/Vigenere-cipher Clark, D. (2020). Kasiski Analysis: Breaking the Code. Crypto Corner. https://crypto.interactive-maths.com/kasiski-analysis-breaking-the- code.html Respectfully, Carolina

Answer

Introduction

The Vigenère cipher is indeed a fascinating encryption method (Levy, 2018). It’s a polyalphabetic substitution cipher, meaning it uses multiple substitution alphabets to encode the plaintext. Each letter of the plaintext is shifted according to the corresponding letter in the keyword. The table you mentioned is the heart of the Vigenère cipher, used for both encryption and decryption.

Strengths of the Vigenère Cipher

1. Security (at the time): As you mentioned, the Vigenère cipher was initially considered unbreakable (Levy, 2018). This was due to its use of a keyword that could be of varying lengths, which made traditional frequency analysis ineffective. Only until Kasiski and Babbage’s work did its vulnerability become apparent.
2. Variable Key Length: The ability to use keywords of different lengths provided flexibility (Singh, 2018). This meant you could encrypt messages using various keys, which could make it quite secure if used properly.

Weaknesses of the Vigenère Cipher

1. Repetition: The Achilles’ heel of the Vigenère cipher was the repetition of the keyword in the ciphertext. As you noted, the Kasiski Test exploited this weakness (Rezende, 2019). By identifying repeated sequences and calculating their distance, cryptanalysts could deduce the keyword length.
2. Vulnerability to Frequency Analysis: Although the Vigenère cipher initially seemed immune to frequency analysis due to the multiple alphabets used, once the keyword length was known, frequency analysis could be applied to each of the individual Caesar ciphers within the polyalphabetic cipher.

Historical Significance

The Vigenère cipher played a pivotal role in the history of cryptography (Singh, 2018). While Giovan Battista Bellaso is credited with its invention, the mistaken attribution to Blaise de Vigenère lent the cipher its name. Vigenère’s recognition in the cryptology community demonstrates the enduring power of an influential name in academic circles.

Unraveling the Vigenère Cipher: Historical Insights and Cryptographic Vulnerabilities

In conclusion, the Vigenère cipher, though ultimately broken, had a remarkable run as an apparently unbreakable code. The cryptographic breakthroughs in understanding its weaknesses paved the way for modern encryption methods. It’s an example of how even seemingly secure systems can be cracked with time, effort, and the right analytical techniques.

Now, let’s delve further into the historical context of the Vigenère cipher and explore its enduring legacy.

Historical Context of the Vigenère Cipher

The 16th century was a period of great intrigue and espionage, and the Vigenère cipher found its place in this historical context. While often credited to Blaise de Vigenère, it was, in fact, Giovan Battista Bellaso who first introduced a similar cipher in 1553 (Simmons, 2023). Bellaso’s cipher, known as the “Tabula Recta,” had elements that would later evolve into the Vigenère cipher.

However, the mistaken attribution to Vigenère himself is a fascinating example of historical misattribution (Levy, 2018). This misattribution occurred when a later historian, Chifflet, confused Bellaso’s work with that of Vigenère. As a result, the cipher was named after Vigenère, further cementing the incorrect credit.

The Vigenère cipher, despite its cryptanalytical vulnerability, had an impressive run of over three centuries as a secure means of communication. During this period, it was considered unbreakable, and its security rested on the repetitive use of a keyword of varying lengths (Clark, 2020). Decrypting it required knowledge of the keyword, making it a challenging code for adversaries.

Cryptanalysis of the Vigenère Cipher

As you mentioned, the Vigenère cipher’s security was eventually compromised through the work of Friedrich Wilhem Kasiski and Charles Babbage. Kasiski introduced a technique known as the Kasiski Examination (Rezende, 2019). This method aimed to identify repeated sequences in the ciphertext, which often corresponded to the repeated use of the keyword. Once the repeated sequences were identified, the…

By understanding the historical context and the cryptographic vulnerabilities of the Vigenère cipher, we gain a more comprehensive view of its significance and the enduring legacy of cryptanalysis. This knowledge underscores the importance of continuous advancements in cryptography and the constant need for enhanced security measures in our digital age.

References

• Clark, D. (2020). Kasiski Analysis: Breaking the Code. Crypto Corner. Link
• Levy, S. (2018). Crypto: How the Code Rebels Beat the Government—Saving Privacy in the Digital Age. Penguin.
• Rezende, R. (2019). Classical Cryptography: A Comprehensive Overview of Vigenère and Playfair Ciphers. In 2019 IEEE Latin American Symposium on Circuits and Systems (LASCAS) (pp. 1-4). IEEE.
• Simmons, G. (2023). Vigenere Cipher. Britannica. Link
• Singh, S. (2018). The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography. Anchor.

FAQs

1. What is the Vigenère cipher, and why is it historically significant?

• The Vigenère cipher is a polyalphabetic substitution cipher that encrypts text using a code key and a Vigenère table. It played a pivotal role in the history of cryptography, often credited to Blaise de Vigenère, but initially introduced by Giovan Battista Bellaso in 1553.

2. What made the Vigenère cipher seemingly unbreakable at first?

• The Vigenère cipher appeared unbreakable due to its variable-length keyword, making traditional frequency analysis ineffective in decrypting messages.

3. How was the Vigenère cipher eventually decrypted?

• The Kasiski Examination, introduced by Friedrich Wilhem Kasiski, exploited the repetition of the keyword in the ciphertext. Once repeated sequences were identified, the keyword’s length could be deduced, allowing for decryption.

4. What role did historical misattribution play in the cipher’s name?

• Historian Chifflet mistakenly attributed the Vigenère cipher to Blaise de Vigenère, even though Giovan Battista Bellaso was its true originator. This misattribution led to the cipher being named after Vigenère.

5. What lessons can we draw from the Vigenère cipher’s history for modern cryptography?

• The Vigenère cipher’s history highlights the importance of continuous advancements in cryptography. It reminds us that no code is unbreakable forever, and cryptography must adapt to new challenges in our digital age.