caeaser.py

def encrypt(string, shift):
    cipher = ''
    for char in string:
        if char == ' ':
            cipher = cipher + char
        elif char.isupper():
            cipher = cipher + chr((ord(char) + shift - 65) % 26 + 65)
        else:
            cipher = cipher + chr((ord(char) + shift - 97) % 26 + 97)
    return cipher

def decrypt(string, shift):
    cipher = ''
    for char in string:
        if char == ' ':
            cipher = cipher + char
        elif char.isupper():
            cipher = cipher + chr((ord(char) + (26-shift) - 65) % 26 + 65)
        else:
            cipher = cipher + chr((ord(char) + (26-shift) - 97) % 26 + 97)
    return cipher

text = input("Enter String : ")
s = int(input("enter Shift Number : "))

option = int(input("1. For Encrypt \n2. For Decrypt\n Enter Your choice : "))

print("Original String : ", text)
if( option == 1):
    print("After Encryption : ", encrypt(text, s))
else:
    print("After Decryption : ", decrypt(text, s))