Caesar Cipher Python

caesarCipher.py

# we need 2 helper mappings, from letters to ints and the inverse
L2I = dict(zip("ABCDEFGHIJKLMNOPQRSTUVWXYZ",range(26)))
I2L = dict(zip(range(26),"ABCDEFGHIJKLMNOPQRSTUVWXYZ"))

key = 3
plaintext = "DEFEND THE EAST WALL OF THE CASTLE"

# encipher
ciphertext = ""
for c in plaintext.upper():
    if c.isalpha(): ciphertext += I2L[ (L2I[c] + key)%26 ]
    else: ciphertext += c

# decipher
plaintext2 = ""
for c in ciphertext.upper():
    if c.isalpha(): plaintext2 += I2L[ (L2I[c] - key)%26 ]
    else: plaintext2 += c

print plaintext
print ciphertext
print plaintext2

how can i run in cent os 7

lol

:D

lol
arr = "abcdefghijklmnopqrstuwxyz"

key = 3
plain = "hello world 2day"
cyper = "";
for c in plain:
if c.isalpha() : cyper += arr[(arr.index(c)+3)%26]
else: cyper += c

print(cyper)

To reverse the cipher negate the value of the key. This will reverse the cipher and give back your initial text. Just adding this. I also stripped out the decipher part. It did really nothing.

##This is my code, very proud definitely not copy and pasted.##
L2I = dict(zip("ABCDEFGHIJKLMNOPQRSTUVWXYZ",range(26)))
I2L = dict(zip(range(26),"ABCDEFGHIJKLMNOPQRSTUVWXYZ"))

key = 3
plaintext = (input("Enter text you would like to cipher:"))

ciphertext = ""
for c in plaintext.upper():
if c.isalpha(): ciphertext += I2L[ (L2I[c] + key)%26 ]
else: ciphertext += c

plaintext2 = ""
for c in ciphertext.upper():
if c.isalpha(): plaintext2 += I2L[ (L2I[c] - key)%26 ]
else: plaintext2 += c

print(plaintext)
print(ciphertext)
print(plaintext2)

you can use instead;
import string
L2I = dict(zip(string.ascii_uppercase,range(26)))

a = list(input())
b = int(input())
s = ''
for i in range(0, len(a)):
c = ord(a[i])
c -= b
if c < ord('A'):
c += 26
s += chr(c)
print(s)
decoding the Caesar cipher

You cant use chr() and ord() because they use the whole ASCII library, which also includes lowercase and non alphanumerical characters, which may result in the wrong decryption.

print ("my balls hurt")

import time
plain = input("Enter your encryption: ")
time.sleep(0.5)
print("Decrypting...")
dcypher = ""

for c in plain:
if c.isalpha():
dcypher += arr[(arr.index(c) + -3) % 26]
else:
dcypher += c
time.sleep(1)
print(dcypher)

simple decipher code that you could use

I'm using this code for homework, and the sentence that I'm using has an exclamation mark at the end, but I have to remove it. what code would I need to add?

You could use a for loop to build a new string which is a copy of the old string, but only includes characters that are a-z. There are lots of ways of achieving it. Regards, James

…

On Tue, 27 Apr 2021, 3:50 pm TeacherChristian, ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ I'm using this code for homework, but the sentence that I'm using has an exclamation mark at the end, but I have to remove it. what code would I need to add? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <https://gist.github.com/8701593#gistcomment-3721131>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAM7KQK6USLVAZB75UZRAG3TKZGBTANCNFSM4J3N64AQ> .

Could you please give me an example of what that code would look like? I'm new to Python and this stuff is kinda out of my league. Thank you.

You could use a for loop to build a new string which is a copy of the old string, but only includes characters that are a-z. There are lots of ways of achieving it. Regards, James
…
On Tue, 27 Apr 2021, 3:50 pm TeacherChristian, @.***> wrote: @Christian198231 commented on this gist. ------------------------------ I'm using this code for homework, but the sentence that I'm using has an exclamation mark at the end, but I have to remove it. what code would I need to add? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://gist.github.com/8701593#gistcomment-3721131, or unsubscribe https://github.com/notifications/unsubscribe-auth/AAM7KQK6USLVAZB75UZRAG3TKZGBTANCNFSM4J3N64AQ .

I needed to edit a littell bit to run on python3 but I like it good job pro : ).