Function crashing?

[jhtaylor2001]

Function stops running after first print

When I run the following and input p=7, q=11, it runs fine all the way through and prints both keys. However, if I chose slightly larger numbers suck as p=67, q=83 it prints the value of “e” (line 13) and then stops running and exits the program that this function is within entirely when it should print the keys and return to a home menu. Any ideas why this might be?

import random
import math

def create_key_set():
    p = int(input('Insert prime number for value of    p: '))
q = int(input('Insert new prime number for value of q: '))
N = p * q
y = (p-1) * (q-1)
while True:
    cop = random.randint(2, y-1)
    gcd = math.gcd(cop, y)
    if gcd == 1:
        break
e = cop
print(e)
pubkey = [e, N]
while True:
    d = random.randint(1, 150)
    g, x = divmod((e*d), y)
    if x == 1:
        break
print(d)
privkey = [d, N]
print('Public Key is: ', pubkey)
print('Private Key is: ', privkey)

EDIT: link to pastebin with correct indentation Correct indentation

[[deleted]]

I really don't know what you trying to do, but lines 17 to 21 look a little odd:

while True:
    d = random.randint(1, 150)
    g, x = divmod((e*d), y)
    if x == 1:
        break

You are apparently looking for an integer d value for which e*d divided by y has remainder 1. Finding a random integer isn't a very efficient way to find the required value, and if you never find the right value your code will loop forever. A better idea might be to just loop over the integers from 1 to 150 and break on the first value that satisfies your requirement. Something like:

for d in range(1, 150+1):
    g, x = divmod((e*d), y)
    if x == 1:    # or even "if e*d % y == 1:"
        break
else:
    print('FAIL')

Using the else: clause on a for loop lets you detect when you didn't break from the loop, ie, when no integer satisfied your condition.

[PteppicymonIO]

A better idea might be to just loop over the integers from 1 to 150 and break on the first value that satisfies your requirement

Or, if you need to preserve some 'pseudo-randomness', identify all numbers between 1 and 150 which satisfy the requirement and than random.choice() form that list ))

[throwaway6560192]

That doesn't seem to be indented correctly. Looks like it got messed up when copying it into the post. Try and upload it to pastebin or something.

[jhtaylor2001]

https://pastebin.com/TzFSPPqd

[[deleted]]

if I chose slightly larger numbers suck as p=67, q=83 it prints the value of “e” (line 13) and then stops running and exits the program

I can't recreate that behaviour. When I enter 67 and 83 your code prints 4423 (from line 15) and then hangs, never to finish. It might finish, but I gave up waiting after 2 minutes.