Question 1 A columnar transposition cipher scheme is used for two parties who communicate securely over an open channel. The eavesdropper knows that the number of columns used in this cipher is not more than eight (8). The following ciphertext is captured by an eavesdropper: itaeini nratnim tetneex otdfope icrhxcu methrer wseithe (a) Show the method to cryptanalyze the ciphertext by using the bigram. (5 marks) (b) Show the sums of frequency of 5 different possible solutions (widths). (3 marks) (c) Show the most likely plaintext and number of letters in each cipher block. A non- continuous plaintext could be obtained if the eavesdropped sequence is composed of two fractions from two consecutive cipher blocks. (7 marks) (Total 15 marks) se th 1.52% em 0.55% mg 0.18%) he 1.28% ed 0.53% of 0.16% in 0.94% to 0.52% al 0.09% er 0.94% it 0.50% de 0.09% an 0.82% ou 0.50% 0.08% re 0.68% ea 0.47% le 0.08% nd 0.63% hi 0.46% sa 0.06% at 0.59% is 0.46% si 0.05% 0.57% or 0.43% ar 0.04% nt 0.56% ti 0.34% ve 0.04% ha 0.56% as 0.33% ra 0.04% es 0.56% te 0.27% ld 0.02% st 0.55% et 0.19% ur 0.02% on Question 1 A columnar transposition cipher scheme is used for two parties who communicate securely over an open channel. The eavesdropper knows that the number of columns used in this cipher is not more than eight (8). The following ciphertext is captured by an eavesdropper: itaeini nratnim tetneex otdfope icrhxcu methrer wseithe (a) Show the method to cryptanalyze the ciphertext by using the bigram. (5 marks) (b) Show the sums of frequency of 5 different possible solutions (widths). (3 marks) (c) Show the most likely plaintext and number of letters in each cipher block. A non- continuous plaintext could be obtained if the eavesdropped sequence is composed of two fractions from two consecutive cipher blocks. (7 marks) (Total 15 marks) se th 1.52% em 0.55% mg 0.18%) he 1.28% ed 0.53% of 0.16% in 0.94% to 0.52% al 0.09% er 0.94% it 0.50% de 0.09% an 0.82% ou 0.50% 0.08% re 0.68% ea 0.47% le 0.08% nd 0.63% hi 0.46% sa 0.06% at 0.59% is 0.46% si 0.05% 0.57% or 0.43% ar 0.04% nt 0.56% ti 0.34% ve 0.04% ha 0.56% as 0.33% ra 0.04% es 0.56% te 0.27% ld 0.02% st 0.55% et 0.19% ur 0.02% on