# Frequency analysis to find key

cipherBlockList $=[]$

for i in range$(0,$ len$($cipherbin$),$ BLOCKSIZE$)$:

block $=$ BitVector$($bitstring$=$cipherbin$[$i: i $+$ BLOCKSIZE$])$

cipherBlockList.append$($block$)$

cipherBlockList.insert$(0,$ bv$\_$iv$)$

plainXorKey $=[]$

for i in range$(1,$ len$($cipherBlockList$))$:

xor$\_$result $=$ cipherBlockList$[$i$]^$ cipherBlockList$[$i $-1]$

plainXorKey.append$($xor$\_$result$)$

plainXorKey $=$ list$($reversed$($plainXorKey$))$

NUM$\_$ROWS $=$ BLOCKSIZE $//8$

table $=[[]$ for $\_$ in range$($NUM$\_$ROWS$)]$

for xor$\_$value in reversed$($plainXorKey$)$:

xor$\_$str $=$ str$($xor$\_$value$)$

for k in range$(0,$ len$($xor$\_$str$),$ numbytes$)$:

table$[$k $//8].$append$($xor$\_$str$[$k: k $+$ numbytes$])$

decryption$\_$key $=""$

for row in table:

most$\_$frequent$\_$char $=$ find$\_$most$\_$frequent$($row$)$

temp$\_$key$\_$part $=$ guess$\_$key$\_$part$($row$,$ most$\_$frequent$\_$char$)$

decryption$\_$key $+=$ temp$\_$key$\_$part $($please explain this part in detail with real life example how it is guessing$)$