Summary The Solution of the Zodiac Killer’s 340-Character Cipher—Wolfram Blog blog.wolfram.com
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Sam Blake and David Oranchak successfully decrypted a portion of the Zodiac Killer's 340-character cipher with the help of Mathematica and AZdecrypt, and their solution was verified by the FBI.
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Slide Presentation (8 slides)
Key Points
- The Zodiac Killer sent taunting letters to the press with encrypted ciphers in the 1960s and 70s.
- The Zodiac Killer's 340-character cipher, known as Z340, had resisted decryption for 50 years.
- A combination of a homophonic substitution cipher and a transposition cipher was used in Z340.
- Mathematica was used to analyze and search for potential transpositions and solutions to Z340.
- After extensive analysis and experimentation, a partial decryption of Z340 was achieved.
- The FBI confirmed the validity of the solution to Z340.
- The decryption process involved identifying key phrases and using AZdecrypt for solving homophonic substitution ciphers.
- Further analysis and decryption efforts are still needed for the remaining segments of Z340.
Summaries
21 word summary
Sam Blake and David Oranchak decrypted part of the Zodiac Killer's 340-character cipher using Mathematica and AZdecrypt. FBI confirmed their solution.
70 word summary
Sam Blake and David Oranchak have partially decrypted the Zodiac Killer's 340-character cipher after 50 years. They used Mathematica to explore transpositions and conducted an extensive search. Comparing bigram counts of random ciphers led to significant observations. With the help of AZdecrypt, they found a solution for the first segment and partially decrypted the last segment. The FBI confirmed their solution as valid, marking a breakthrough in decrypting the cipher.
134 word summary
The Zodiac Killer's 340-character cipher, unsolved for 50 years, has been partially decrypted by Sam Blake and David Oranchak. Using Mathematica, Blake explored transpositions of the cipher, including a period-19 transposition, but did not find a match. He then investigated a 1,2-decimation but also came up empty. However, he made significant observations by comparing bigram counts of random ciphers. Blake conducted an extensive search of candidate transpositions and considered encrypting the cipher into multiple segments. Eventually, he discovered a candidate decryption that produced intriguing plaintext segments. Working with Oranchak, they used AZdecrypt to crib phrases, leading to a solution for the first segment and partial decryption of the last segment. The FBI confirmed their solution as valid. The collaboration and use of Mathematica resulted in a significant breakthrough in decrypting the Zodiac Killer's cipher.
411 word summary
The Zodiac Killer, an unidentified American serial killer active during the 1960s and 70s, sent three ciphers to the press in the San Francisco area. The killer claimed that deciphering the 408-character cryptogram would reveal his identity, but it was decoded in 1969 without revealing any significant information. In 2020, Sam Blake decided to investigate the Zodiac Killer's 340-character cipher (Z340) after being inspired by a YouTube video by David Oranchak. The Z340 had remained unsolved for 50 years and was considered a major challenge in cryptography.
Using Mathematica, Sam Blake explored various transpositions of the Z340 cipher. Although he discovered a period-19 transposition with interesting statistical properties, it did not match the transposition found by another user. Sam then investigated a 1,2-decimation of the cipher but did not find a solution. However, this exploration led him to consider the likelihood of finding the correct transposition of a homophonic substitution cipher by counting repeating bigrams. He compared the bigram count distribution of random shuffles of the Z340 with random Z340-like ciphers and made significant observations.
Sam conducted an extensive search through candidate transpositions but did not find a solution. He also considered encrypting the cipher into multiple segments with transpositions and homophonic substitutions. By using Reduce, he found that proper two-dimensional decimations resulted in interesting transpositions. After testing various segmentations and transpositions, Sam discovered a candidate decryption for the Z340 cipher that produced some intriguing segments of plaintext.
Working with David Oranchak, Sam used AZdecrypt to crib certain phrases in the first segment of the Z340 cipher. With these cribs, they found a solution for the first segment and applied the key to the last segment, resulting in a partial decryption without any transposition. They also made progress in decrypting parts of the second segment through specific observations and corrections to the decrypted text.
After 51 years, Sam and David successfully decrypted some of the Z340 cipher. They submitted their solution to the FBI, and it was confirmed to be valid. Sam primarily used Mathematica for his analysis and visualizations, as well as the Spartan high-performance computing cluster at the University of Melbourne.
In conclusion, the collaboration between Sam Blake and David Oranchak, along with the use of Mathematica, led to the partial decryption of the Zodiac Killer's 340-character cipher. This breakthrough was achieved through statistical analysis, transposition searches, and cribbing techniques. The solution of the Z340 cipher marks a significant milestone in the investigation of the Zodiac Killer's cryptic messages.
548 word summary
The Zodiac Killer, an unidentified American serial killer active during the 1960s and 70s, sent taunting letters to the press in the San Francisco area, including three ciphers. The killer claimed that the 408-character cryptogram would reveal his identity when deciphered. After the cryptogram was deciphered in 1969 without revealing the killer's identity, the killer sent a fourth and final cipher to the San Francisco Chronicle. In 2020, Sam Blake, inspired by a YouTube video by David Oranchak, decided to investigate the Zodiac Killer's 340-character cipher (Z340). The cipher had resisted attacks for 50 years and was considered one of the holy grails of cryptography.
Sam Blake used Mathematica to explore possible transpositions of the Z340 cipher. He discovered a period-19 transposition that had interesting statistical properties, but it did not match the transposition discovered by user daikon and Jarl van Eycke. Sam then investigated a 1,2-decimation of the cipher, which involved moving one vertical step and two horizontal steps, wrapping periodically both horizontally and vertically. Although this transposition did not produce a solution, it led Sam to consider the likelihood of finding the correct transposition of a homophonic substitution cipher by counting the number of repeating bigrams. He compared the bigram count distribution of random shuffles of the Z340 with random Z340-like ciphers and found that the Z340 had 25 repeating bigrams, while the period-19 transposition and the 1,2-decimation had 37 repeating bigrams.
Sam then conducted a large search through candidate transpositions, testing various combinations of transpositions. However, this search did not yield a solution. He also considered splitting the cipher into multiple segments and encrypting each segment with a transposition and a homophonic substitution. Sam used Reduce to compute all possible segmentations and found that proper two-dimensional decimations resulted in interesting transpositions. After testing various segmentations and transpositions, Sam discovered a candidate decryption for the Z340 cipher that produced some interesting segments of plaintext.
Sam worked with David and used AZdecrypt to crib the phrases "HOPE YOU ARE," "TRYING TO CATCH ME," and "THE GAS CHAMBER" in the first segment of the Z340 cipher. With these cribs, AZdecrypt found a solution for the first segment. They then applied the key from the first segment to the last segment, which produced a partial decryption without any transposition. They also decrypted parts of the second segment but were not able to fully decrypt it. However, they made progress by applying specific observations and corrections to the decrypted text.
After 51 years, Sam and David had decrypted some of the Z340 cipher. They submitted their solution to the FBI Cryptanalysis and Racketeering Records Unit, and the FBI confirmed the validity of their solution. Sam conducted most of his work on the Z340 cipher using Mathematica, utilizing its statistical analysis capabilities and visualizations. He also used the Spartan high-performance computing cluster at the University of Melbourne to eliminate candidate transpositions.
In conclusion, after years of resistance, the Zodiac Killer's 340-character cipher has been partially decrypted using a combination of statistical analysis, transposition searches, and cribbing techniques. The decryption was made possible by the collaboration between Sam Blake and David Oranchak, as well as the use of Mathematica for analysis and visualization. The solution of the Z340 cipher marks a significant breakthrough in the investigation of the Zodiac Killer's cryptic messages.