2.8 A disadvantage of the general monoalphabetic cipher is that both sender and receiver must commit the permuted cipher sequence to memory. A common technique for avoiding this is to use a keyword from which the cipher sequence can be generated For example, using the keyword CIPHER, write out the keyword followed by unused letters in normal order and match this against the plaintext le plain: abcdefghjk1mnop rstuvwxyz If it is felt that this process does not produce sufficient mixing, write the remaining letters on successive lines and then generate the sequence by reading down the columns: CIPH E R A BDF GJ K L M N O Q ST UV WX Y Z 58 CHAPTER 2 / CLASSICAL ENCRYPTION TECHNIQUES This yields the sequence: Such a system is used in the example in Section 2.2 (the one that begins "it was dis- closed yesterday"). Determine the keyword. 2.8 A disadvantage of the general monoalphabetic cipher is that both sender and receiver must commit the permuted cipher sequence to memory. A common technique for avoiding this is to use a keyword from which the cipher sequence can be generated For example, using the keyword CIPHER, write out the keyword followed by unused letters in normal order and match this against the plaintext le plain: abcdefghjk1mnop rstuvwxyz If it is felt that this process does not produce sufficient mixing, write the remaining letters on successive lines and then generate the sequence by reading down the columns: CIPH E R A BDF GJ K L M N O Q ST UV WX Y Z 58 CHAPTER 2 / CLASSICAL ENCRYPTION TECHNIQUES This yields the sequence: Such a system is used in the example in Section 2.2 (the one that begins "it was dis- closed yesterday"). Determine the keyword