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Blackboard with a the Pigpen cipher keys drawn in the middle. The pigpen cipher (alternately referred to as the masonic cipher, Freemason's cipher, Napoleon cipher, and tic-tac-toe cipher) is a geometric simple substitution cipher, which exchanges le

Blackboard with a the Pigpen cipher keys drawn in the middle. The pigpen cipher (alternately referred to as the masonic cipher, Freemason's cipher, Napoleon cipher, and tic-tac-toe cipher) is a geometric simple substitution cipher, which exchanges le