Random Password Generator with Python

The goal of this exercise is to write a code that generates a Random Password with Python.

The function is named randomPassword, and it generates a random password that takes no parameters.

The password criteria are as follows:

• The password will have a random length of between 7 and 10 characters.

• Each character will be randomly selected from positions 33 to 126 from the ASCII table.

Solution

# coding: utf-8

# In[46]:

def randomPassword():

    """
    A function to randomly generate password with a length between 7 and 10.

    Input:
    No input

    Return:
    password - the generated password.
    """

    from random import randint # Importing the random generator function

    # CONSTANTS
    MIN_PASSWORD_LENGTH = 7
    MAX_PASSWORD_LENGTH = 10
    MIN_ASCII = 33
    MAX_ASCII = 126

    # Obtaining a random password length within the limits specified in the constants
    password_length = randint(MIN_PASSWORD_LENGTH, MAX_PASSWORD_LENGTH)

    # Array for storing the randomly generated password characters
    gen_chars = []

    # The loop for the generation of the random characters
    for _ in range(password_length):

        # Obtaining an ASCII number randomly within the limit of the constants.
        random_ascii = randint(MIN_ASCII, MAX_ASCII)

        # Converting the ASCII number to a character
        new_char = chr(random_ascii)
        # Adding the new character to the array of generated password characters
        gen_chars.append(new_char)

        # End of Loop

    # Joining all the generated characters together to form a string type object
    password = ''.join(gen_chars)

    return password # returning the jointed characters as the password

if __name__ == "__main__":

    # Calling the created function
    mypassword = randomPassword()

    # Displaying the output of the function
    print("Generated password: ", mypassword)

Code Explanation

This Python code defines a function randomPassword() that generates a random password with a length between 7 and 10 characters. Let's break down the code in detail, including explanations and code snippets.

The code is structured into two main parts: the randomPassword() function definition and the if __name__ == "__main__": block, which demonstrates how to use the function.

1. randomPassword() Function

This function is designed to generate a random password.

def randomPassword():
    """
    A function to randomly generate password with a length between 7 and 10.

    Input:
    No input

    Return:
    password - the generated password.
    """

• def randomPassword():: This line defines a function named randomPassword(). It takes no arguments.

• Docstring ("""..."""): This is a multi-line string used to explain what the function does, its inputs, and what it returns. It's good practice for documenting code.

    from random import randint # Importing the random generator function

• from random import randint: This line imports the randint function from Python's built-in random module.

  • randint(a, b): This function returns a random integer N such that a <= N <= b. This is crucial for generating random lengths and random ASCII values.

    # CONSTANTS
    MIN_PASSWORD_LENGTH = 7
    MAX_PASSWORD_LENGTH = 10
    MIN_ASCII = 33
    MAX_ASCII = 126

• Constants: These variables are defined in uppercase by convention to indicate that their values are not expected to change during the program's execution.

  • MIN_PASSWORD_LENGTH = 7: The minimum allowed length for the generated password.

  • MAX_PASSWORD_LENGTH = 10: The maximum allowed length for the generated password.

  • MIN_ASCII = 33: The minimum ASCII (American Standard Code for Information Interchange) value to consider for password characters. ASCII 33 is the '!' character.

  • MAX_ASCII = 126: The maximum ASCII value to consider for password characters. ASCII 126 is the '~' character.

    • Why ASCII 33 to 126? This range includes printable characters, including numbers (0-9), uppercase letters (A-Z), lowercase letters (a-z), and various symbols (e.g., !, @, #, $, %, ^, &, *). This makes the generated passwords more robust than just using letters and numbers.

    # Obtaining a random password length within the limits specified in the constants
    password_length = randint(MIN_PASSWORD_LENGTH, MAX_PASSWORD_LENGTH)

• password_length = randint(MIN_PASSWORD_LENGTH, MAX_PASSWORD_LENGTH): This line uses randint to determine the actual length of the password. It will be a random integer between 7 and 10 (10 inclusive).

    # Array for storing the randomly generated password characters
    gen_chars = []

• gen_chars = []: An empty list named gen_chars is initialized. This list will temporarily store individual characters as they are generated before they are joined together to form the final password string.

    # The loop for the generation of the random characters
    for _ in range(password_length):

        # Obtaining an ASCII number randomly within the limit of the constants.
        random_ascii = randint(MIN_ASCII, MAX_ASCII)

        # Converting the ASCII number to a character
        new_char = chr(random_ascii)

        # Adding the new character to the array of generated password characters
        gen_chars.append(new_char)

        # End of Loop

• for _ in range(password_length):: This is a for loop that iterates password_length times (e.g., 7 to 10 times, depending on the randomly chosen length).

  • The underscore _ is used as the loop variable when you don't need to use the actual iteration number inside the loop (it's just a placeholder).

• random_ascii = randint(MIN_ASCII, MAX_ASCII): Inside each iteration, a random integer is generated between MIN_ASCII (33) and MAX_ASCII (126). This integer represents the ASCII code of a character.

• new_char = chr(random_ascii): The chr() built-in function is used to convert an integer (ASCII value) into its corresponding character. For example, chr(65) returns 'A', chr(97) returns 'a', and chr(48) returns '0'.

• gen_chars.append(new_char): The newly generated character (new_char) is added to the gen_chars list.

    # Joining all the generated characters together to form a string type object
    password = ''.join(gen_chars)

    return password # returning the jointed characters as the password

• password = ''.join(gen_chars): After the loop finishes, all the individual characters stored in the gen_chars list are joined together to form a single string. The '' before .join() means that the characters will be joined with an empty string as a separator (i.e., no separation, just concatenated).

• return password: The function returns the final generated password string.

2. if __name__ == "__main__": Block

This block of code is a standard Python idiom.

if __name__ == "__main__":

    # Calling the created function
    mypassword = randomPassword()

    # Displaying the output of the function
    print("Generated password: ", mypassword)

• if __name__ == "__main__":: This condition checks if the script is being run directly (as the main program) rather than being imported as a module into another script.

  • If you run your_script.py directly, __name__ will be "__main__".

  • If you import your_script.py into another script (e.g., import your_script), then __name__ in your_script.py will be your_script, and the code inside this block will not execute.

  • This is useful for putting code that should only run when the script is executed as a standalone program (like testing or demonstration code).

• mypassword = randomPassword(): The randomPassword() function is called, and the returned password string is stored in the mypassword variable.

• print("Generated password: ", mypassword): This line prints the generated password to the console, prefixed with the label "Generated password: ".