Question

Python code. NO importing modules. you may not use: contains(), index(), sum(),join(), split().

def column_cipher(plaintext):

• Parameter(s): plaintext ----- a string; the message to be encrypted
• Return value: A string; the ciphertext after applying the column cipher algorithm • Assumptions:

o The standard English alphabet is used: "abcdefghijklmnopqrstuvwxyz"

o All strings will be non-empty, entirely lowercase, and only contain valid letters in the alphabet. • How it works:

o First, transpose the text into 5 different columns by writing each letter from left to right, moving onto the next line after you exhaust all of the columns on a single line. Then, build the cipher text by combining each column from left to right.

For example, with the plaintext: "thequickbrownfoxjumped":
o First, transpose the text into 5 different columns (spaces added for clarity, they are not required):

_

thequ ickbr ownfo xjump e d______

o Now, read each column one at a time:

Column #0: "tioxe" Column #1: "hcwjd" Column #2: "eknu" Column #3: "qbfm" Column #4: "urop"

o Combine the columns from left to right.
§ Your final cipher text is: "tioxehcwjdeknuqbfmurop"

• Examples:
o column_cipher("gotosecretspotatfive") → 'gestocpftroioetvstae' o column_cipher("areyouhungry") → 'aurrhyeuynog'

fence_cipher('asdfjjcmmzkisjdkfpqoerutoqierjsdfmcmmsdjcmdjcmssdfgf'), 'adjcmksdfqeuoirsfcmdcdcsdgsfjmzijkportqejdmmsjmjmsff')

Answer 1

def column_cipher(plaintext):

ans = ""; i= 0 ; j= 0; res = ""

lst = []

while(i<len(plaintext)):

    j = i

    ans = "";

    while(j <len(plaintext)):

      if j not in lst:

        ans = ans + plaintext[j]

        lst.append(j)

      j = j + 5

    res = res + ans

    i = i + 1

return res

print(column_cipher("thequickbrownfoxjumped"))

#tioxehcwjdeknuqbfmurop

print(column_cipher("gotosecretspotatfive"))

#'gestocpftroioetvstae'

print(column_cipher("areyouhungry"))

#aurrh yeuyn og

===================================================
SEE OUTPUT

Python 3.7.4 (default, Jul 9 2019 06:43) [GCC 6.3.0 20170516] on linux tioxehcwjdeknuqbfmurop gestocpftroioetvstae aurrhyeuynog main.py saved 1 def column_cipher(plaintext): ans = ""; i= 0; j= 0; res = Ist = [] while(islen(plaintext)): j = i ans = ""; while(j <len(plaintext)): if j not in lst: ans = ans + plaintext[j] lst.append(j) j = j + 5 res = res + ans i = i + 1 return res print(column_cipher("thequickbrownfoxjumped")) #tioxehcwjdeknuqbfmurop print(column_cipher("gotosecretspotatfive")) #'gestocpftroioetvstae print(column_cipher("areyouhungry")) #aurrh yeuyn og 20 21



Thanks, PLEASE COMMENT if there is any concern.