Deciphering the Zodiac Killer's 340-Character Cipher

Основные понятия

Deciphering the Zodiac Killer's 340-character cipher involves a combination of transposition and homophonic substitution.

Аннотация

The content delves into the historical significance of the Zodiac Killer's ciphers, focusing on the unsolved 340-character cipher. It explores the challenges faced in decoding the cipher, highlighting the unique qualities of the cipher and the various attempts made by experts and researchers. The analysis includes observations, measurements, and hypotheses from the FBI and other researchers, suggesting a combination of transposition and homophonic substitution in the encryption method.

Directory:

1. Background
   • Zodiac Killer's crimes and communication.
   • Introduction of ciphers.
2. Homophonic Substitution Ciphers
   • Evolution and vulnerabilities.
   • Use of multiple substitutions.
3. Transposition Ciphers
   • Historical use and methods.
   • Contrast with substitution ciphers.
4. Z408 Cipher Solution
   • Decryption process and key findings.
5. Z340 Cipher Analysis
   • Challenges in decryption.
   • Observations and measurements.
6. FBI Observations and Hypotheses
   • Insights from the FBI's analysis.
7. Conjecture: Z340 Encryption
   • Combination of transposition and substitution.

Статистика

The FBI suspected a transposition might have been applied as an additional step in Z340’s encipherment.
Berg-Kirkpatrick et al. (2013) argued that Z340 is not likely strictly homophonic.
Yi (2014) suspected Z340 used a combination of substitution and columnar transposition.
Juzek's cipher classification method in 2019 categorized Z340 as an "advanced cipher" or "pseudo-cipher."

Цитаты

"The FBI tried applying the Z408 key as part of a 'combination cryptosystem', including linear and route transposition, with a negative result."

FBI Cryptanalysis Report

Ключевые выводы из

The Solution of the Zodiac Killer's 340-Character Cipher

by David Oranch... в arxiv.org 03-27-2024

https://arxiv.org/pdf/2403.17350.pdf

Дополнительные вопросы

What impact does the combination of transposition and homophonic substitution have on the complexity of the Zodiac Killer's cipher

The combination of transposition and homophonic substitution in the Zodiac Killer's cipher significantly increases its complexity. Transposition involves rearranging the symbols in the ciphertext, making it harder to decipher as the original order of the letters is obscured. On the other hand, homophonic substitution replaces each plaintext letter with multiple cipher symbols, further complicating the decryption process by introducing variability in the substitutions. When these two techniques are combined, the resulting cipher becomes much more challenging to crack. The transposition adds an additional layer of complexity to the already intricate homophonic substitution, making it harder for cryptanalysts to unravel the message hidden within the cipher.

How do the observations and measurements of the cipher support the hypothesis of a mixed encryption method

The observations and measurements of the Zodiac Killer's cipher support the hypothesis of a mixed encryption method involving transposition and homophonic substitution. The presence of repeating trigrams and bigrams in the ciphertext, the absence of repetitions within certain regions, the unusual clustering of symbols, and the unique patterns like the "backwards L" shapes suggest a deliberate and purposeful encryption process beyond simple substitution. These features align with the characteristics expected in a cipher that combines transposition and homophonic substitution. Additionally, the FBI's observations of randomness in different rows and columns of the cipher grid indicate a more complex encryption technique at play, further supporting the mixed encryption method hypothesis.

How has the online community's collaboration influenced the analysis and decryption attempts of the Zodiac Killer's ciphers

The online community's collaboration has had a significant impact on the analysis and decryption attempts of the Zodiac Killer's ciphers. Through online forums, blogs, emails, and social media platforms, a diverse group of individuals with varying skills and expertise have come together to share insights, observations, and hypotheses about the ciphers. This collaborative effort has led to the discovery of unique patterns, the exploration of different encryption techniques, and the development of computational tools for cryptanalysis. By pooling their knowledge and resources, the online community has facilitated a more comprehensive and thorough examination of the ciphers, contributing to a deeper understanding of the encryption methods used by the Zodiac Killer.