For my class assignment, I was given this text;
Qpuvu vo vv stazpuykzh Hhycmlmv asb. Ad dhyaqva wh uyo uzb jpwww Avlw. Tkpjllfdmbp zoatz vzjavfvna ZLHqh. Amva luy yyvlz yu bhk zua zlhvvalaz yow llh uldu llzy yzlvao. Hzk caslyv kfzounf zayy sh pvsv. Uopz ala yrvhbhm tk ppp Thlll jya. Blz o bblw tol Lsjay hba ljw oro lp nta avlnktn.
There is more than one cipher method used, with one of their keys being 'ANNIE'
POSSIBLE METHODS: Caesar, Vigenère, One-Time Pad, Columnar Transposition, Railfence Transposition...
Using Cryptool 1 to analyze the histogram, I figured out that there's a Caesar shift 7 cipher, which decodes the text to:
Jinon oh oo lmtsinrdsa Aarvfefo tlu. Tw wartjot pa nrh nsu cippp Toep. Mdiceeywfui shtms osctoyogt SEAja. Tfot enr rroes rn uad snt seaootets rhp eea newn eesr rseoth. Asd vtlero dyshngy strr la iolo. Nhis tet rkoauaf md iii Maeee crt. Ues h uuep mhe Elctr aut ecp hkh ei gmt toegdmg.
I figured out the plaintext by using columnar transposition through a website.
jamesisanundercoverinterpolcophereportstoouroldenemysuptshamshuddinusingencryptedsmsestheyareawareofallouractivitesforthelastfourmonthsthepolicesuspectthatweknowtheyareworkingtogetjamesoutsetatrapforjamesandgetridofhimtonight
Is there a way I can explain why it couldn't have been Vigenère or a one-time pad? Is my assumption that a mono substitution cipher cannot be combined with a poly substitution cipher correct?