Required: Add a decryption statement using

python language

alphabet = "abcdefghijklmnopqrstuvwxyz"

#message = input("Enter the plaintext")

#key = input("Enter the key")

#two dictionaries to map index to letters and letter to index

letter_to_index = dict(zip(alphabet, range(len(alphabet))))

index_to_letter = dict(zip(range(len(alphabet)), alphabet))

# :

def encrypt(message, key):

encrypted =""

#split the message to the length of the key

split_message = [

message [i: i + len (key)] for i in range (0, len(message), len(message), len(key))

]#(start,stop,step)

#loop that start at 0 then contunue to the length of the message with jum

for each_split in split_message :

i=0

for each_letter in each_split:

#p+k mod 26

number = (letter_to_index[each_letter] + letter_to_index[key[i]]) % 26

encrypted += index_to_letter [number]

i += 1

return encrypted

def main ():

message = input("Enter the plaintext: ")

key = input("Enter the key: ")

encrypted_message = encrypt(message, key)

print("the encrypted message is: " + encrypted_message)

main()