The following three ciphers are known as the ‘Feynman Challenge Ciphers’ or the ‘Feynman Ciphers’.
They were, according to a 1987 post by Chris Cole (then at Peregrine Systems) to the Usenet group sci.crypt, passed to Nobel Laureate physicist Richard Feynman by a (currently unidentified) fellow scientist at Los Alamos. Though cipher #1 has been cracked, the other two remain unbroken.
Feynman Challenge Cipher #1 (Solved by Jack C. Morrison of JPL)
MEOTAIHSIBRTEWDGLGKNLANEAINOEEPEYST NPEUOOEHRONLTIROSDHEOTNPHGAAETOHSZO TTENTKEPADLYPHEODOWCFORRRNLCUEEEEOP GMRLHNNDFTOENEALKEHHEATTHNMESCNSHIR AETDAHLHEMTETRFSWEDOEOENEGFHETAEDGH RLNNGOAAEOCMTURRSLTDIDOREHNHEHNAYVT IERHEENECTRNVIOUOEHOTRNWSAYIFSNSHOE MRTRREUAUUHOHOOHCDCHTEEISEVRLSKLIHI IAPCHRHSIHPSNWTOIISISHHNWEMTIEYAFEL NRENLEERYIPHBEROTEVPHNTYATIERTIHEEA WTWVHTASETHHSDNGEIEAYNHHHNNHTW
This is a 5 x 76 transposition cipher, where you start with the letter in the final position (‘W’) and then repeatedly step back through the whole ciphertext 5 positions at a time time, and then repeat that same process but starting from the letter one before the last position (‘T’) etc, revealing the first words of Geoffrey Chaucer’s ‘Canterbury Tales’:-
WHANTHATAPRILLEWITHHISSHOURESSOOTET HEDROGHTEOFMARCHHATHPERCEDTOTHEROOT EANDBATHEDEVERYVEYNEINSWICHLICOUROF WHICHVERTUENGENDREDISTHEFLOURWHANZE PHIRUSEEKWITHHISSWEETEBREFTHINSPIRE DHATHINEVERYHOLTANDHEETHTHETENDRECR OPPESANDTHEYONGESONNEHATHINTHERAMHI SHALVECOURSYRONNEANDSMALEFOWELESMAK ENMELODYETHATSLEPENALTHENYGHTWITHOP ENYESOPRIKETHHEMNATUREINHIRCORAGEST HANNELONGENFOLKTOGOONONPILGRIM
Feynman Challenge Cipher #2
XUKEXWSLZJUAXUNKIGWFSOZRAWURORKXAOS LHROBXBTKCMUWDVPTFBLMKEFVWMUXTVTWUI DDJVZKBRMCWOIWYDXMLUFPVSHAGSVWUFWOR CWUIDUJCNVTTBERTUNOJUZHVTWKORSVRZSV VFSQXOCMUWPYTRLGBMCYPOJCLRIYTVFCCMU WUFPOXCNMCIWMSKPXEDLYIQKDJWIWCJUMVR CJUMVRKXWURKPSEEIWZVXULEIOETOOFWKBI UXPXUGOWLFPWUSCH
Feynman Challenge Cipher #3
WURVFXGJYTHEIZXSQXOBGSVRUDOOJXATBKT ARVIXPYTMYABMVUFXPXKUJVPLSDVTGNGOSI GLWURPKFCVGELLRNNGLPYTFVTPXAJOSCWRO DORWNWSICLFKEMOTGJYCRRAOJVNTODVMNSQ IVICRBICRUDCSKXYPDMDROJUZICRVFWXIFP XIVVIEPYTDOIAVRBOOXWRAKPSZXTZKVROSW CRCFVEESOLWKTOBXAUXVB