cipher.py

# AIM: To Decrypt a text using MCMC approach. i.e. find decryption key which we will call cipher from now on.
import string
import math
import random

# This function takes as input a decryption key and creates a dict for key where each letter in the decryption key
# maps to a alphabet For example if the decryption key is "DGHJKL...." this function will create a dict like {D:A,G:B,H:C....} 
def create_cipher_dict(cipher):
    cipher_dict = {}
    alphabet_list = list(string.ascii_uppercase)
    for i in range(len(cipher)):
        cipher_dict[alphabet_list[i]] = cipher[i]
    return cipher_dict

# This function takes a text and applies the cipher/key on the text and returns text.
def apply_cipher_on_text(text,cipher):
    cipher_dict = create_cipher_dict(cipher) 
    text = list(text)
    newtext = ""
    for elem in text:
        if elem.upper() in cipher_dict:
            newtext+=cipher_dict[elem.upper()]
        else:
            newtext+=" "
    return newtext