Answer to Question #346018 in Python for Nir

Question

Cipher with Key

A Keyword Cipher is a monoalpha

uses a key to provide en ption

In a substitution cipher each letter of

matched with a different letter accord to phetet

Using these letter matchings, every letter of the esse

substituted to get the encrypted messag

In a keyword cipher, the key determines the let he ciphertext alphabet is created by keeping the lette the beginning (after removing the repeated letters then the rest of remaining letters are used in aph

For example, if the key is zebras

Plaintext Alphabet: albicidjeifigibili Ciphertext Alphabet : zjelb/r/als/cidition

Notice that with this key, we are able to match each lecer of engl alphabet with a different letter. Using these matchings we can encrypt the word discovered as rpbluacerda

replaced with f,i is replaced with and soon

Given a key K and the message M, encrypt the message Keyword Cipher, using the given key

Input

The first tine contains two

Answer 1

def cipherDictionary(key):  # case sensetive version
    alphabet = "ABCDEFGHIGKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz,.-!?"
    cipherDict = dict()
    cipherDict[" "] = " " #remain spaces
    added = set()
    i = 0
    for letter in alphabet:
        index = ord(key[i])%len(alphabet)   # ord() gets the ASCII number of a letter in key
        while(index in added):
            index = ( index+5 )%len(alphabet)
        added.add(index)
        cipherDict[letter] = alphabet[index]
        i = (i+1)%len(key)  #move to next letter in key
    return cipherDict
    
def encrypt(text, key):
    cipher = cipherDictionary(key)
    encrypted = ""
    for i in text:
        encrypted+=(cipher[i])
    return encrypted


def decrypt(text, key):
    decipher = {v: k for k, v in cipherDictionary(key).items()}
    decrypted = ""
    for i in text:
        decrypted+=(decipher[i])
    return decrypted


while True:
    print("Encrypt - 1, dectypt - 2, exit - q: ")
    mode = input()
    if(mode == 'q'):
        break
    if(mode!='1'and mode!='2'):
        continue


    print("Enter the message: ")
    message = input()
    print("Enter the keywoard: ")
    keyword = input()
    if (mode == '1'):
        print(encrypt(message,keyword) )
    elif (mode == '2'):
        print(decrypt(message,keyword) )