Develop Reference

Need Guidance with some Python code (Substitute Cypher Python)

I have some code already but I got feedback on how to pass the rest of the criteria but I have no idea how to do it.
Assignment brief:
You are working in a Newspaper office that handles the reports from their journalists. You have been asked to design a program that will be used to help them send confidential reports in that others cannot read as email is not secure, we need to generate an encryption key that they can encode their scoops and documents when sent by email.
The program will need to generate the key. Encode the message, export the key, import a key from another person and decode a message. It will be a simple substitution cipher. The key needs to be made up out of all Alphanumeric Characters and some Special Characters. It will be a single key per session so you will need to save the key if you close the program otherwise you won’t be able to decode those messages used to encode them.
All projects start with planning it is the most important part that can make or break a project so ensure this is carried out correctly
Pass, Merit and Distinction Requirements
What the feedback says to do:
You were asked to import a key and export a key your program doesn't allow this so you would need to resubmit to get Pass4 and Pass6
Code I have done so far below
def run():
x=input("code or decode? ")
if x == "code":
a=list("")
import string
alpha = str("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz")
message=input("What is your message to encode? ")
x=len(message)
y=0
z=0
for counter in range(x):
y=y+1
letter = alpha.find(message[z:y])
z=z+1
letter=letter+13
if letter > 24:
letter=letter-24
letter=alpha[letter:letter+1]
if counter != x-1:
print(letter,end="")
else:
print(letter)
x=input("type yes to go again? ")
if x == "yes":
run()
else:
input()
else:
a=list("")
import string
alpha = str("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz")
message=input("What is your message to decode? ")
x=len(message)
y=0
z=0
for counter in range(x):
y=y+1
letter = alpha.find(message[z:y])
z=z+1
letter=letter-13
if letter < 0:
letter=24+letter
letter=alpha[letter:letter+1]
if counter != x-1:
print(letter,end="")
else:
print(letter)
x=input("again? ")
if x == "yes":
run()
else:
input()
run()

I did some research and come up with this.
You can use it as it is or edit it to meet your needs. Hope it helps.
Update.1: The longer the message, the bigger the encryption key will be. One solution for this is to use zlib.compress method in order to shrink the key, and then decompress it when needed.
Update.2: Added the export/import functionality of the encryption key using a Json file (you can of course choose other way of storing data) along with a title assigned to it, so you have the choice to either enter the title or enter the encryption key of the message for decryption. The title is just optional and for simplicity purposes, you can get rid of it if you want to. You'll also notice the code contains lots of if/else statements, that's just so you know where you currently are and what choices you have.
A GUI based would be better.
import string
import json
import os
# A list containing all characters
alpha = string.ascii_letters
def code(title, message, key = 6):
temp_dict = {}
cipher=[]
for i in range(len(alpha)):
temp_dict[alpha [i]] = alpha [(i+key)%len(alpha )]
# Generating the encryption key
for char in message:
if char in alpha :
temp = temp_dict[char]
cipher.append(temp)
else:
temp =char
cipher.append(temp)
# This code is needed to decode the expected message so make sure to save it by any method you want,
# otherwhise it'll generate a random text.
cipher= "".join(cipher)
main_data = {title : cipher}
file_name = "encryption_key.json"
if os.path.exists(file_name):
with open(file_name, "r+") as file:
data = json.load(file)
data[0].update(main_data)
file.seek(0)
json.dump(data, file)
else:
with open(file_name, "w") as file:
json.dump([main_data], file)
print("Encryption code :",cipher)
def decode(cipher, key = 6):
temp_dict = {}
for i in range(len(alpha)):
temp_dict[alpha [i]] = alpha [(i-key)%(len(alpha ))]
# Decoding the message
decoded_text = []
for char in cipher:
if char in alpha :
temp = temp_dict[char]
decoded_text.append(temp)
else:
temp = char
decoded_text.append(temp)
decoded_text = "".join(decoded_text)
return decoded_text
while True:
# There is an optional parameter (key) within the function which you can change according to your preference.
# The default value is 5 and it needs to be the same in both encode and decodefunctions.
x=input('[E]ncode or [D]ecode? answer with "e/d:" ')
if x.lower() == "e":
title = input("Enter the title of the message: ")
message = input("What is your message to encode? ")
code(title, message)
break
elif x.lower() == "d":
file_name = "encryption_key.json"
if os.path.exists(file_name):
with open(file_name, "r+") as file:
data = json.load(file)[0]
else:
print("There is no related file for decryption.")
continue
choice = input('Enter the [T]itle or the [K]ey of the message for decryption. [A]ll to decrypt everything on the file. answer with "t/k/a:" ')
if choice.lower() == 't':
title = input("Enter the title: ")
if title in data.keys():
encryption_key = data[title]
print(decode(encryption_key))
break
else:
print("There is no such title.")
elif choice.lower() == "k":
encryption_key = input("Enter the encryption code related to the message? ")
if encryption_key in data.values():
print(decode(encryption_key))
break
else:
print("There is no such encryption key.")
elif choice.lower() == "a":
decrypt_dict = {}
for k, v in data.items():
decrypt_dict[k] = decode(v)
print(decrypt_dict)
break
else:
print("There is no related file for decryption.")
else:
print("Enter a valid answer.")

How to loop a code in Python?

I have this Caesar's Cipher code in Python to encrypt some messages quickly, and show it to my classmates.
I have everything done, except something...
I want to make a 'Do you want to encrypt another message?' option, but I can't loop the code.
How can I loop the whole code? I'm using Python 3.5.1.
Here's my code:
print('QuantumShadow\'s Caesar Cipher')
message = input('Write your message here: ')
print('The encryption key is: ')
key = int(input())
print('Do you want to encrypt or decrypt?')
mode = input()
LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
translated = ''
message = message.upper()
for symbol in message:
if symbol in LETTERS:
num = LETTERS.find(symbol)
if mode == 'encrypt':
num = num + key
elif mode == 'decrypt':
num = num - key
if num >= len(LETTERS):
num = num - len(LETTERS)
elif num < 0:
num = num + len(LETTERS)
translated = translated + LETTERS[num]
else:
translated = translated + symbol
print(translated)
print('Do you want to encrypt\\decrypt another message?')
print('Here is where I want to make the loop')
print('Coded with Python by QuantumShadow.')

One way to do it is using a while loop that goes on forever (until you break out of it):
while True:
# The rest of your code
if not input("Do you want to encrypt or decrypt another message [y/n]? ").lower().startswith("y"):
break
print("Coded with Python by QuantumShadow.")

The simplest way would be to put the whole code inside a 'while running' loop, and in the end of the loop ask if the person wants to run the code again, if not, change running to False.
Before
print("Hello World!")
After
running = True
while running:
print("Hello World!")
answer = input("Would you like to run again? (y/N)")
if answer != 'y':
running = False
But the right way to do it would be to divide your code into functions, so the final result would be cleaner and easier to read.

After the print of the title line start the while loop
ask = True
while ask: # this was initialized to True
message = input('Write your message here: ')
key = int(input('The encryption key is: '))
mode = input('Do you want to encrypt or decrypt?')
# put the coding logic here
next = input('Do you want to encrypt\\decrypt another message?')
if next.lower() == 'no':
ask = False
print('You have finished all messages')

#APerson's solution works fine. Try it out.
while True:
print('QuantumShadow\'s Caesar Cipher')
message = input('Write your message here: ')
print('The encryption key is: ')
key = int(input())
print('Do you want to encrypt or decrypt?')
mode = input()
LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
translated = ''
message = message.upper()
for symbol in message:
if symbol in LETTERS:
num = LETTERS.find(symbol)
if mode == 'encrypt':
num = num + key
elif mode == 'decrypt':
num = num - key
if num >= len(LETTERS):
num = num - len(LETTERS)
elif num < 0:
num = num + len(LETTERS)
translated = translated + LETTERS[num]
else:
translated = translated + symbol
print(translated)
if input("Do you want to encrypt or decrypt another message [yes/no]? ") != "yes":
break
print("Coded with Python by QuantumShadow.")
Also consider moving print(translated) to outside of the for loop so the program only displays the final encrypted result.

put this code above your code:
x=1
while x==1:
Your Code after indent
#Add the following lines below
x=input("Press to send another message or any other key to exit")
the above method is a simple one and needs little modification to your existing code. Hope it helps!

print('QuantumShadow\'s Caesar Cipher')
LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
#Wrap your code
def get_message():
message = input('Write your message here: (input q to quit)')
if message == 'q':
return message
print('The encryption key is: ')
key = int(input())
print('Do you want to encrypt or decrypt?')
mode = input()
translated = ''
message = message.upper()
for symbol in message:
if symbol in LETTERS:
num = LETTERS.find(symbol)
if mode == 'encrypt':
num = num + key
elif mode == 'decrypt':
num = num - key
if num >= len(LETTERS):
num = num - len(LETTERS)
elif num < 0:
num = num + len(LETTERS)
translated = translated + LETTERS[num]
else:
translated = translated + symbol
return translated
#loop your code
while True:
message = get_message()
if message == 'q':
break
print (message)

Getting a Value Error When I Shouldn't Be

I'm trying to have my input move on when enter is pushed on a line with only spaces or just a blank, it doesn't work though it gives me a value error once before it gives me the proper return, which in turn seems to append an extra value to my array and screws over the entire program.
import math
def getItems():
quitNow = False
while not quitNow:
prepTotal = []
paintTotal = []
priceTotal1 = []
priceTotal1d = []
priceTotal2 = []
priceTotal2d = []
names = []
loopQuit = False
index = 1
while not loopQuit:
ans = raw_input("Enter a Name and press Enter to Continue\nEnter \"Q\" to Quit and get the Full Price: ")
if(ans.lower() != "q"):
innerLoopQuit = False
names.append(ans)
print "\nPlease enter your prep hours for " + names[index-1] + ": "
while not innerLoopQuit:
try:
inp = raw_input()
if(inp == ""):
innerLoopQuit = True
else:
float(inp)
prepTotal.append(float(raw_input()))
except ValueError:
print "Please enter a valid number."

You're calling raw_input() again in your else clause. Also, float(inp) doesn't really do anything if you don't assign it anywhere. prepTotal.append(float(inp)) is what you want to do.

Why doesn't my 'oldUser()' run and why does it start again all the time?

I'm very very new to programming and for a school project (50% of my final grade) I had to create a Python program that did roughly this.
I've had some help from my older brother and my teacher but mainly did it myself with some flow charts etc, so please forgive me if I haven't followed conventional rules and things of this nature, or if my code is messy. I will finalise it, just needed bait of help/support from the pro's.
This is my code and I have an issue with it. Once I have pressed 'y' and then 'y' again on the displayMenu() why doesn't it run oldUser()
Also, if any of you have any suggestion on what could make my code better, or I could improve it would be very helpful and I will take it on board.
import os # allows me to use functions defined elsewhere. os module allows for multi platforming.
import sys
words = []
users = {}
status = ""
def teacher_enter_words():
done = False
print 'Hello, please can you enter a word and definition pair.'
while not done:
word = raw_input('\nEnter a word: ')
deff = raw_input('Enter the definition: ')
# append a tuple to the list so it can't be edited.
words.append((word, deff))
add_word = raw_input('Add another word? (y/n): ')
if add_word.lower() == 'n':
done = True
def student_take_test():
student_score = 0
for pair in words:
print 'Definition:', pair[1]
inp = raw_input('Enter word: ')
student_score += check_error(pair[0], inp)
print 'Correct spelling:', pair[0], '\n'
print 'Your score:', student_score
def check_error(correct, inputt):
len_c = len(correct)
len_i = len(inputt)
# threshold is how many incorrect letters do we allow before a
# minor error becomes a major error.
# 1 - allow 1 incorrect letter for a minor error ( >= 2 becomes major error)
threshold = 1
# immediately check if the words are the same length
num_letters_incorrect = abs(len_c - len_i) # abs() method returns value of x - positive dist between x and zero
if num_letters_incorrect == 0:
for i in xrange(0, len(correct)):
if correct[i] != inputt[i]:
num_letters_incorrect += 1
if num_letters_incorrect <= threshold:
if num_letters_incorrect == 0:
return 2 # no incorrect letter.
else:
return 1 # minor error.
else:
return 0 # major error.
def displayMenu():
status = raw_input('Are you a registered user? y/n?: ')
if status == raw_input == 'y':
oldUser()
elif status == 'n':
newUser()
def newUser():
createLogin = raw_input('Create login name: ')
if createLogin in users:
print '\nLogin name already exist!\n'
else:
createPassw = raw_input('Create password: ')
users[createLogin] = createPassw
print '\nUser created!\n'
def oldUser():
login = raw_input('Enter login name: ')
passw = raw_input('Enter password: ')
if login in users and users[login] == passw:
print '\nLogin successful!\n'
else:
print "\nUser doesn't exist or wrong password!\n"
if __name__ == '__main__':
running = True
while running:
os.system('cls' if os.name == 'nt' else 'clear') # multi-platform, executing a shell command
reg = raw_input('Do you want to start the program? y/n?').lower()
if reg == 'y' or reg == 'yes':
displayMenu()
else: sys.exit(0)
inp = raw_input('Are you a Teacher or a Student? (t/s): ').lower()
if inp == 't' or inp == 'teacher':
teacher_enter_words()
else:
student_take_test()
running = False

raw_input is a function. status == raw_input == 'y' will never be true: that is comparing status with the function, and with 'y'.
I suspect that's simply a typo, and you just meant if status == 'y':

Why does python, when I run my program comes up with the error 'expected an indented block?

I am trying to get my program to limit what the user can type in. It keeps returning an "Expected an indented block" error from my code below.
deliverydetails = input("Is your order for delivery?\n Press 1 for delivery. Press 2 for pickup")
if deliverydetails == "1":
## def delivery ():
print ("Order for Delivery")
customerfirstname = " "
while len(customerfirstname) <3 or len(customerfirstname)>30 or customerfirstname.isalpha() != True:
customerfirstname = input("Customer First Name: ** must be 4 characters long + " ")
while len(customersurname) < 3 or len(customersurname) > 30 or customerfirstname.isalpha() != True:
customersurname = input("Customer Surname:" + " ")
customerstreet = input("Street name:" + " ")
customerstreetnumber = input("Street number:" + " ")
customercity = input("City:" + " ")
customersuburb = input("Suburb (If none, leave blank):" + " ")
latestOrder.append(customerfirstname)
latestOrder.append(customersurname)
latestOrder.append(customerstreet)
latestOrder.append(customerstreetnumber)
latestOrder.append(customercity)
latestOrder.append(customersuburb)

Python uses indentation to group blocks of code. After the while statements, you want to indent the lines below it that should be executed inside the while loop.
Here are some other tips that may be useful:
- Use pylint to check your syntax. It will uncover a lot of errors that you would otherwise only find out during runtime.
- Use spaces to indent. Don't use tabs. That's a PEP 8 style recommendation
Here is the corrected version of your code:
deliverydetails = input("Is your order for delivery?\n Press 1 for delivery. Press 2 for pickup")
if deliverydetails == "1":
## def delivery ():
print ("Order for Delivery")
customerfirstname = " "
customersurname = " "
while len(customerfirstname) <3 or len(customerfirstname)>30 or customerfirstname.isalpha() != True:
customerfirstname = input("Customer First Name: ** must be 4 characters long + " ")
while len(customersurname) < 3 or len(customersurname) > 30 or customerfirstname.isalpha() != True:
customersurname = input("Customer Surname:" + " ")
customerstreet = input("Street name:" + " ")
customerstreetnumber = input("Street number:" + " ")
customercity = input("City:" + " ")
customersuburb = input("Suburb (If none, leave blank):" + " ")
latestOrder.append(customerfirstname)
latestOrder.append(customersurname)
latestOrder.append(customerstreet)
latestOrder.append(customerstreetnumber)
latestOrder.append(customercity)
latestOrder.append(customersuburb)

Python uses intentation instead of {} or begin/end, so for example this line
while len(customerfirstname) <3 or len(customerfirstname)>30 or customerfirstname.isalpha() != True:
should be followed by an indented block. An indented block can be as short as a single line, usually you should indent it 4 spaces more than the while
Aside: it may be clearer to write that line as
while not (3 <= len(customerfirstname) <= 30 and customerfirstname.isalpha()):

Make sure to indent the lines that are part of the loop. That's the only way Python has to know what part you want to loop.
delivery_details = input("Is your order for delivery?\n Press 1 for delivery. Press 2 for pickup")
if delivery_details == "1":
print "Order for Delivery"
customer_first_name = ""
while len(customer_first_name) < 3 or len(customer_first_name) > 30 or not customer_first_name.isalpha():
customer_first_name = input("First name (must be 4 characters long): ")
customer_surname = input("Surname: ")
customer_street = input("Street name: ")
customer_street_number = input("Street number: ")
customer_city = input("City: ")
customer_suburb = input("Suburb (If none, leave blank): ")
latest_order.append(customer_first_name)
latest_order.append(customer_surname)
latest_order.append(customer_street)
latest_order.append(customer_street_number)
latest_order.append(customer_city)
latest_order.append(customer_suburb)
For what it's worth I've made some stylistic changes for readability. Some extra spacing, blank lines, and underscores in variable names make everything a bit easier on the eyes.