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Cryptanalysis Example. Cipher text. cop raqv obl eqmp qipa cop kppr pmk hxlc obip b hxcymw kxayme gzbll ptpgxcp bc obzv rblc vqxa lbw bahbkyzzq cq gbzz yc qvv. Suppose ‘e’ is the most common. cop raqv obl eqmp qipa cop kppr pmk e e e e ee e
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Cipher text cop raqv obl eqmp qipa cop kppr pmk hxlc obip b hxcymw kxayme gzbll ptpgxcp bc obzv rblc vqxa lbw bahbkyzzq cq gbzz yc qvv
Suppose ‘e’ is the most common cop raqv obl eqmp qipa cop kppr pmk e e e e ee e fp hxlc obip b hxcymw kxayme gzbll e e ptpgxcp bc obzv rblc vqxa lbw e e e bahbkyzzq cq gbzz yc qvv
“the” may appear twice cop raqv obl eqmp qipa cop kppr pmk the h e e the ee e fp hxlc obip b hxcymw kxayme gzbll e t h e t ptpgxcp bc obzv rblc vqxa lbw e e te t h t bahbkyzzq cq gbzz yc qvv t t
‘a’ is also common cop raqv obl eqmp qipa cop kppr pmk the ha e e the ee e fp hxlc obip b hxcymw kxayme gzbll e t ha e a t a ptpgxcp bc obzv rblc vqxa lbw e e te at ha a t a bahbkyzzq cq gbzz yc qvv a a t a t
‘y’ must be ‘i’ cop raqv obl eqmp qipa cop kppr pmk the ha e e the ee e fp hxlc obip b hxcymw kxayme gzbll e t ha e a ti i a ptpgxcp bc obzv rblc vqxa lbw e e te at ha a t a bahbkyzzq cq gbzz yc qvv a a i t a it
Is ‘l’ ‘s’? cop raqv obl eqmp qipa cop kppr pmk the has e e the ee e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti i ass ptpgxcp bc obzv rblc vqxa lbw e e te at ha ast sa bahbkyzzq cq gbzz yc qvv a a i t a it
‘q’ must be ‘o’ cop raqv obl eqmp qipa cop kppr pmk the o has o e o e the ee e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti i ass ptpgxcp bc obzv rblc vqxa lbw e e te at ha ast o sa bahbkyzzq cq gbzz yc qvv a a i o to a it o
Double letters likely ‘l’ cop raqv obl eqmp qipa cop kppr pmk the o has o e o e the ee e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti i lass ptpgxcp bc obzv rblc vqxa lbw e e te at hal ast o sa bahbkyzzq cq gbzz yc qvv a a illo to all it o
‘g’ into ‘f’? cop raqv obl eqmp qipa cop kppr pmk the o has o e o e the ee e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti i flass ptpgxcp bc obzv rblc vqxa lbw e ef te at hal ast o sa bahbkyzzq cq gbzz yc qvv a a illo to fall it o
‘c’ is more likely cop raqv obl eqmp qipa cop kppr pmk the o has o e o e the ee e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti i class ptpgxcp bc obzv rblc vqxa lbw e ec te at hal ast o sa bahbkyzzq cq gbzz yc qvv a a illo to call it o
‘v’ possibilities cop raqv obl eqmp qipa cop kppr pmk the od has o e o e the ee e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti i class ptpgxcp bc obzv rblc vqxa lbw e ec te at hald ast o sa bahbkyzzq cq gbzz yc qvv a a illo to call it odd
‘f’ works better cop raqv obl eqmp qipa cop kppr pmk the of has o e o e the ee e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti i class ptpgxcp bc obzv rblc vqxa lbw e ec te at half ast fo sa bahbkyzzq cq gbzz yc qvv a a illo to call it off
“half mast” makes sense… cop raqv obl eqmp qipa cop kppr pmk the m of has o e o e the eem e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti i class ptpgxcp bc obzv rblc vqxa lbw e ec te at half mast fo sa bahbkyzzq cq gbzz yc qvv a a illo to call it off
But “half past” works better cop raqv obl eqmp qipa cop kppr pmk the p of has o e o e the eep e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti i class ptpgxcp bc obzv rblc vqxa lbw e ec te at half past fo sa bahbkyzzq cq gbzz yc qvv a a illo to call it off
That must be “prof”! cop raqv obl eqmp qipa cop kppr pmk the prof has o e o er the eep e fp hxlc obip b hxcymw kxayme gzbll e st ha e a ti ri class ptpgxcp bc obzv rblc vqxa lbw e ec te at half past fo r sa bahbkyzzq cq gbzz yc qvv ar a illo to call it off
‘i’ as ‘v’ cop raqv obl eqmp qipa cop kppr pmk the prof has o e over the eep e fp hxlc obip b hxcymw kxayme gzbll e st have a ti ri class ptpgxcp bc obzv rblc vqxa lbw e ec te at half past fo r sa bahbkyzzq cq gbzz yc qvv ar a illo to call it off
Only ‘d’ works here cop raqv obl eqmp qipa cop kppr pmk the prof has o e over the deep e d fp hxlc obip b hxcymw kxayme gzbll e st have a ti d ri class ptpgxcp bc obzv rblc vqxa lbw e ec te at half past fo r sa bahbkyzzq cq gbzz yc qvv ar adillo to call it off
First line solved! cop raqv obl eqmp qipa cop kppr pmk the prof has gone over the deep end fp hxlc obip b hxcymw kxayme gzbll e m st have a m tin d ring class ptpgxcp bc obzv rblc vqxa lbw e ec te at half past fo r sa bahbkyzzq cq gbzz yc qvv armadillo to call it off
Found the last vowel cop raqv obl eqmp qipa cop kppr pmk the prof has gone over the deep end fp hxlc obip b hxcymw kxayme gzbll e must have a mutin during class ptpgxcp bc obzv rblc vqxa lbw e ecute at half past four sa bahbkyzzq cq gbzz yc qvv armadillo to call it off
Finished! cop raqv obl eqmp qipa cop kppr pmk the prof has gone over the deep end fp hxlc obip b hxcymw kxayme gzbll we must have a mutiny during class ptpgxcp bc obzv rblc vqxa lbw execute at half past four say bahbkyzzq cq gbzz yc qvv armadillo to call it off