Table of Content

1. Context
2. Algorithm
3. Pre-requisite
4. Functions and operation we will use
6. Output
7. Full Code Here

Context

Our passwords keep our valuable accounts safe and secured. The more these passwords are unpredictable , the more our account is secured. In general , a most secured password needs at least one uppercase and one lowercase letter , one digit and one special character and the password length should be at least 8.

In terms of creating a password , we always try to create one that we can easily remember.

The National Cyber Security Centre (NCSC) said 15% of the population used pets' names, 14% use a family member's name, and 13% pick a notable date. And 6% of people are still using "password" as all - or a part - of their password. ( source : BBC NEWS )

So , in generating a totally random and unpredictable password , an algorithm can be helpful. In this blog , I will write a code for generating a random password in Python.

Algorithm

step by step
Step 1 : Take a user input of password's length.
Step 2 : Substract 4 from the length and store the result in a variable. rest_index= length-4
Step 3 : To make sure your password have at least one uppercase , one lowercase letter, one digit and one character , you need to keep 4 space in the index. That's why we substracted 4 in step 2. Now randomly select one Uppercase , one Lowercase , one digit , one special character and store them in a variable. password+=radom uppercase+random lowercase + random digit + random special character
Step 4 : Now we will shuffle the position of the strings in password so that the index of them become unpredictable as well. password=shuffle the position of all the strings
Step 5 : Now for the rest of the strings , we will execute a loop starting from 0 to length-4 (as we have figured four letter first). password=shuffle the position of all the strings
Step 6 : Now in that loop we will choose one string randomly and we will randomly select would that be a uppercase or lowercase or digit or special charecter . temp = random (Uppercase/ Lowercase/digit/special charecter); if temp=uppercase then pasword+=random uppercase
Step 7 : Now you can print the password. print(pasword)

Pre-requisite:

Python installed
Ide or Idle or run on shell . (I prefer Spyder ide )
Basic concept of how to execute code

Functions and operation we will use

random - module :

This module implements pseudo-random number generators for various distributions.

random.choice(seq) : Return a random element from the non-empty sequence seq.
random.sample(population, k, *, counts=None) : Return a k length list of unique elements chosen from the population sequence or set. Used for random sampling without replacement.

Source: Here is link

String operations :

This module implements pseudo-random number generators for various distributions.
string.ascii_lowercase : The lowercase letters 'abcdefghijklmnopqrstuvwxyz'.
string.ascii_uppercase: The uppercase letters 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'. This value is not locale-dependent and will not change.
string.digits: The string '0123456789'.
string.punctuation: String of ASCII characters which are considered punctuation characters in the C locale: !"#$%&'()*+,-./:;<=>?@[]^_`{|}~.
Source: Here is link

Start coding

Import random module and string module in your code.

import random as rand
import string

take user input of password's length and initialize password string as empty. Substract four from the original length and store it in rest_index. (we will fill up 4 index with 4 fixed string )

print("Enter a length of password at least 8     :")
length=int(input())
password="" 
rest_index=length-4

Randomly choose one uppercase and one lowercase letter , one digit and one special charecter with string and random module. then concat all 4 of them with password variable.
Later shuffle the position of the string with rand.sample() function and use join function to join them as string and then store it in password variable.

password+=rand.choice(string.ascii_uppercase)+rand.choice(string.ascii_lowercase)+ rand.choice(string.digits)+rand.choice(string.punctuation)
password=  ''.join((rand.sample(password,len(password))))

Make a list of choices in variable mainChoice where "U" = uppercase letter; "L" = lowercase letter; "N" = digit; "S" = special charecter;
We will execute a loop from 0 to rest_index (Here rest_index=length-4) and figure out other random string. -To do that , we will randomly choose from the mainChoice list one string and in our if-else condition we will execute according to that.

mainChoice=["U","L","N","S"]          
for x in range(0,rest_index):
    temp=rand.choice(mainChoice)
    if(temp=="U"):
        password+=rand.choice(string.ascii_uppercase)  
    if(temp=="L"):
        password+=rand.choice(string.ascii_lowercase)      
    if(temp=="N"):
        password+= rand.choice(string.digits)     
    if(temp=="S"):
        password+=rand.choice(string.punctuation)

Now we can print the generated password

print(password)

Now run the code and you will see the output like below :

Output

Enter a length of password at least 8     :

8
Your password is :  J?9k]k8&

You can now copy and paste it in anywhere you like. It's random and fully unpredictable.

Full Code Here:

import random as rand
import string

print("Enter a length of password at least 8     :")
length=int(input())
password="" 
rest_index=length-4

password+=rand.choice(string.ascii_uppercase)+rand.choice(string.ascii_lowercase)+ rand.choice(string.digits)+rand.choice(string.punctuation)
password=  ''.join((rand.sample(password,len(password)))) 
mainChoice=["U","L","N","S"]          
for x in range(0,rest_index):
    temp=rand.choice(mainChoice)

    if(temp=="U"):
        password+=rand.choice(string.ascii_uppercase)

    if(temp=="L"):
        password+=rand.choice(string.ascii_lowercase)

    if(temp=="N"):
        password+= rand.choice(string.digits)

    if(temp=="S"):
        password+=rand.choice(string.punctuation)

print("Your password is : ", password)

Make a Simple Random Password Generator in Python