Zodiac-Style Cipher
Decode and analyze homophonic substitution ciphers like those used by the Zodiac Killer. Features symbol frequency analysis.
Enter symbols or use substitution characters (+, /, |, @, #, etc.)
Zodiac Ciphers
The Zodiac Killer was an unidentified serial killer who operated in Northern California in the late 1960s. He sent four cryptograms to newspapers, challenging them to decode his identity.
The Four Zodiac Cryptograms
- Z408: Solved in 1969 by a teacher couple
- Z340: Solved in 2020 by a team of codebreakers
- Z13: 13-character cipher, still unsolved
- Z32: 32-character cipher, still unsolved
Homophonic Substitution
The Zodiac ciphers use homophonic substitution, where each letter can be represented by multiple different symbols. This makes frequency analysis much harder because the frequency distribution is flattened.
Zodiac-Style Puzzles in Geocaching
Homophonic ciphers appear in geocaching puzzles:
- Symbol substitution: Custom symbol alphabets
- Mixed encoding: Letters, numbers, and symbols
- Frequency flattening: Multiple symbols per letter
- Visual puzzles: Symbols that need to be identified
Breaking Homophonic Ciphers
- Count symbol frequencies
- Group symbols that might represent the same letter
- Look for common patterns (THE, AND, ING)
- Use hill-climbing algorithms for larger ciphers
- Check for transposition combined with substitution