Question

For loops and user-defined functions

In cryptography, a Caesar cipher is a method of encryption where each character is
replaced by a corresponding character a defined number of steps away.
Define a cryptographic function, ASCII shift () that will take in two arguments, a string
and a step size.
For every alphabetical character in the original string, the function will make a new string
which shifts each character in the original string by the defined step size, then print the
new string. (You may use the exact comments below in your script as a docstring.)
INPUT:
original string and step size.
PROCESSING:
Create a new variable, shift_string.
Iterate over original string.
For each alphabetical character in original string, convert
the character into Unicode value, add the shift_size,
convert new value into character, and add the new character
to the end of shift string.
For each non-alphabetical character in the original string,
keep the character the same in the shift_string.
OUTPUT: returns shift_string
You will use the ASCII shift() function in your main() function. In main(), ask the
user to input a message to be encrypted and the step size. Print the original and encrypted
messages. The main () function will continually ask the user for inputs and call the
ASCII_shift() function until the user enters the word QUIT (all capital) letters.
Hint: use help () to look up docstring information about chr() and ord() functions.
Below are a few sample runnings in IDLE interactive mode. Underlined text indicates
user input. You can assume there will be no data type entry errors from the user.

Answer 1

I have implemented the ASCII_shift() function according to the provided specifications. This function takes an original string and a step size as input, creating a new string by shifting each alphabetical character by the defined step size. The main() function uses ASCII_shift() to encrypt messages entered by the user, printing both the original and encrypted messages. The program continues to prompt the user for inputs until the user enters "QUIT."

Step-by-step explanation:

The ASCII_shift() function has been designed to handle the encryption process based on the Caesar cipher method. It follows the specified algorithm, iterating through the original string, shifting alphabetical characters by the given step size, and maintaining non-alphabetical characters unchanged. This ensures the accurate encryption of messages.

In the main() function, the user interacts with the program by inputting a message and a step size. The ASCII_shift() function is then called to encrypt the message, and both the original and encrypted messages are displayed. The program continues to prompt the user for inputs until the user enters "QUIT." This interactive design allows users to encrypt multiple messages with different step sizes.

By adhering to the provided instructions and incorporating user interaction, the program offers a practical and efficient way to utilize the Caesar cipher encryption method. Users can easily encrypt their messages while having the flexibility to input new messages until they decide to exit the program.