The dagapeyeff cipher is an as yet unbroken cipher that appears in the first edition of codes and ciphers an elementary book on cryptography published by the russian born english cartographer alexander dagapeyeff in 1939 offered as a challenge cipher at the end of the book it was not . The 11 famous uncracked codes and mysterious ciphertexts that top codebreakers and cryptographers tried to solve it but they never got succeeded. From five lines of letters scrawled on the back of a dead mans book to the taunting codes sent to police by the zodiac killer some of historys most legendary uncracked codes and ciphers represent a fascinating and frustrating challenge even for the worlds brightest cryptographers could