Mystery AtlasZodiac 340-Character Cipher
A 340-symbol cryptogram mailed by the Zodiac Killer on 8 November 1969 that resisted decryption for over fifty years until an independent team of codebreakers solved it in December 2020, a solution the FBI confirmed as genuine; it contained no identifying information about the killer.
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Connected to
How this topic links to the people, places, and ideas around it — drawn from our knowledge graph.
Related Mysteries
- Zodiac KillerDecember 1968 - October 1969
Zodiac 340-Character Cipher was authored by Zodiac Killer.
Historical Context
Zodiac 340-Character Cipher occurred during Cold War.
Objects & Artifacts
Zodiac 340-Character Cipher is frequently compared to Kryptos — Both are real-world cipher artifacts that captured public fascination well beyond cryptography circles; the Zodiac cipher was solved by independent codebreakers in 2020, while Kryptos's K4 remains formally unsolved even after its plaintext surfaced in a 2025 archival leak.
Explored on these pages
What Is Kryptos, the CIA's Unsolved Sculpture Cipher?
What Kryptos is: the CIA's encrypted sculpture, how its first three passages were cracked, and why K4 is still formally unsolved after 35+ years.
Who Was the Zodiac Killer?
Who the Zodiac Killer was: the confirmed 1968-69 California murders, the taunting ciphers, the main suspects, and why the case stays unsolved.