Can you crack the famous unsolved Zodiac 340-character cipher? The SF Chronicle published this cipher that was mailed to them by the Zodiac killer back in 1969. The first cipher he sent was solved by a high school teacher and his wife. The 340-character cipher below remains unsolved. Can you solve it? Try it! Click one of the cipher characters below and type the letter you want to substitute. I will look for some common words as you go and display them to the right. I will also generate some letter/symbol frequency statistics for you. You can start with a randomized set of letters by clicking Randomize below. Or, click on one of the interesting decoders at the bottom of the page to see some interesting decodings of the cipher. If you want to see the first, solved cipher, click the "Switch to 408 cipher" link below, and click "The correct one" to see the cipher's known solution. If you prefer the old webtoy, it is still available via this link. Also, give the Zodiac Decrypto cipher-cracking software a try if you want to attempt a more automated approach. Email me at doranchak at gmail dot com if you find anything interesting or have any comments/suggestions! (go back to Oranchak.com)

Please wait... Loading images... This should not take long...

Randomize | Reset | Toggle stats | Switch to 408 cipher | Switch to 340 cipher | Flip horizontally | Flip vertically | Rotate left | Rotate right |


Technical caveat: I am assuming this is a simple monoalphabetic homophonic substitution cipher, and not something much harder like a transposition cipher or a polyalphabetic substitution cipher. The only reason I am assuming this is because the first 3-part cipher Zodiac sent to the newspaper was solved using homophonic substitution with a single alphabet (to see this, click the "Switch to 408 cipher" link above, and click the decoder named "The correct one").

Click here to view a high-resolution image of the 340 cipher.

(go back to Oranchak.com)