Python Programming: An Introduction to Computer Science, 3rd Ed.
3rd Edition
ISBN: 9781590282755
Author: John Zelle
Publisher: Franklin, Beedle & Associates
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Question
Chapter 5, Problem 8PE
Program Plan Intro
Program plan
- Inside the “main()” function,
- Declare “plaintext” and “key” and get input from the user.
- Create a string of letters and then convert plaintext to ciphertext.
- Print the encoded message.
- Call the function “main()”.
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Example 2
Enter message to be encrypted: Dèyè mòn, gen mòn.
Enter step size: -1
ORIGINAL MESSAGE
Dèyè mòn, gen mòn.
ENCRYPTED MESSAGE
Cçxç lim, fdm lim.
Enter message to be encrypted: Dèyè mòn, gen mòn.
Enter step size: 0
ORIGINAL MESSAGE
Dèyè mòn, gen mòn.
ENCRYPTED MESSAGE
Dèyè mòn, gen mòn.
Enter message to be encrypted: QUIT
Example 3
Enter message to be encrypted: Perfer et obdura, dolor hic tib:
proderit olim.
Enter step size: 8
ORIGINAL MESSAGE
Perfer et obdura, dolor hic tibi proderit olim.
ENCRYPTED MESSAGE
Xmznmz m| wjl)zi, lwtwz pąk |qją xzwlmzą| wtqu.
Enter message to be encrypted: QUIT
Substitution ciphers are encryption/decryption algorithms that replace one letter or number with another. The first attested use of a substitution cipher in military affairs was by Julius Caesar, described by him in Gallic Wars (cf. Kahn pp83-84). In caesar cipher , you replace each letter by 3rd letter on. If it is out of bound (later than Z), then round to the head (letter A) and continue the shift. For example:meet me after the toga party
PHHW PH DIWHU WKH WRJD SDUWB
Please write a program in Java to implement the Caesar Cipher:
a. Implement the encryption algorithm. Ask the user to input one all lower case normal sentence (called plaintext) using the nextLine method, and then output the encrypted text (called ciphertext).
b. Implement the decryption algorithm. Ask the user to input one encrypted sentence (i.e. ciphertext) using the nextLine method, and then output the decrypted text (i.e. plaintext).
Encrypt
Caesar cipher is a kind of substitution cipher. Instead of using a substitution table, the alphabets are rotated by a number (a key). For example, if the key is 3, plaintext alphabet a would become d, and plaintext alphabet z would become c.
Write a program that implements the Caesar Cipher. You program will first prompt for the key and then for the mode (E for encryption and D for decryption) and finally for the message to be encrypted / decrypted. Your program will then output the encryption / decryption message.
For this question, the input message may consists of any character, the program should encrypt or small letter case a to z only. All other characters should be kept intact after encryption or decryption.
Chapter 5 Solutions
Python Programming: An Introduction to Computer Science, 3rd Ed.
Ch. 5 - Prob. 1TFCh. 5 - Prob. 2TFCh. 5 - Prob. 3TFCh. 5 - Prob. 4TFCh. 5 - Prob. 5TFCh. 5 - Prob. 6TFCh. 5 - Prob. 7TFCh. 5 - Prob. 8TFCh. 5 - Prob. 9TFCh. 5 - Prob. 10TF
Ch. 5 - Prob. 1MCCh. 5 - Prob. 2MCCh. 5 - Prob. 3MCCh. 5 - Prob. 4MCCh. 5 - Prob. 5MCCh. 5 - Prob. 6MCCh. 5 - Prob. 7MCCh. 5 - Prob. 8MCCh. 5 - Prob. 9MCCh. 5 - Prob. 10MCCh. 5 - Prob. 1DCh. 5 - Prob. 2DCh. 5 - Prob. 3DCh. 5 - Prob. 4DCh. 5 - Prob. 5DCh. 5 - Prob. 1PECh. 5 - Prob. 2PECh. 5 - Prob. 3PECh. 5 - Prob. 4PECh. 5 - Prob. 5PECh. 5 - Prob. 6PECh. 5 - Prob. 7PECh. 5 - Prob. 8PECh. 5 - Prob. 9PECh. 5 - Prob. 10PECh. 5 - Prob. 11PECh. 5 - Prob. 12PECh. 5 - Prob. 13PECh. 5 - Prob. 14PECh. 5 - Prob. 15PECh. 5 - Prob. 16PE
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