Generate random password types of different complexity using pure python.

genpass.py

#!/usr/bin/env python3
"""
Simple function to create random generated password types.
See examples at the end of gist.
"""
import os, string, random

def genpass(digits=False, length=13, special_char_set='!@#$%',
            repeat_chars=True,
            require_special_char=True,
            require_numbers=True,
            require_uppercase=True,
            require_lowercase=True):
    """
    Generate different password types.
    :param digits: Returns only random digits.
    :param length: Max length of password generated.
    :param special_char_set: Use the supplied chars as special chars.
    :param repeat_chars: True allows repeating of a char.
    :param require_special_char: If set to False, no special characters are generated.
    :param require_numbers: If set to False, no numbers are generated.
    :param require_uppercase: 
    :param require_lowercase:
    :return:
    """
    random.seed = (os.urandom(1024))

    if digits:
        # Used for pin numbers
        chars = string.digits
        password = ''.join(random.choice(chars) for i in range(length))
        return password

    # Generate individual lists of strings.
    letters_lower = string.ascii_lowercase
    letters_upper = string.ascii_uppercase
    numbers = string.digits
    if not special_char_set:
        special_char_set = string.punctuation

    # Generate normal string of options
    chars = letters_lower + letters_upper

    # if required_* set, generate at least 1 required char from lists and concat
    # results to req_chars
    req_chars = ''
    if require_lowercase:
        req_chars += ''.join((random.choice(letters_lower) for i in range(1)))
    if require_uppercase:
        req_chars += ''.join((random.choice(letters_upper) for i in range(1)))
    if require_numbers:
        chars += numbers
        req_chars += ''.join((random.choice(numbers) for i in range(1)))
    if require_special_char:
        chars += special_char_set
        req_chars += ''.join((random.choice(special_char_set) for i in range(1)))

    if not repeat_chars:
        limited_chars = ''.join(random.sample(chars, len(chars)))
        password = ''.join(random.choice(limited_chars) for i in range(length))
    else:
        password = ''.join(random.choice(chars) for i in range(length))

    # if there is a req_char set, then concat the generated password with the req_char and shuffle
    if req_chars:
        # shorten the passsword by the number of req_chars, and concat the req_chars to the password.
        password = password[:-len(req_chars)]
        password += req_chars

        # Convert password to list and shuffle results.
        char_list = list(password)
        random.shuffle(char_list)
        password = ''.join(char_list)
    return password


  
# Examples:
genpass(digits=True, length=50)
#'32960559941701058915204312703775203197166016081777'

genpass(length=50)
#'fMI2X5oicUv%FlT!dHEuSQKkvmM9sexCXhPC99D%Y$!UqTuZx4'

genpass(length=50, require_special_char=False)
#'G5F0nAOyHkwTgo38S9b89BVw7AkYr13HOgOzMMl9fjfvdexpsE'

genpass(length=50, require_numbers=False)
#'aWa!#dq!asLjOKiDVonmsJRH@IxICFaCMsH!rSzZPRQAqncnrv'

genpass(length=50, require_numbers=False, require_special_char=False)
#'OjwneoMymKREuiCoZMERYMOFqOrAyZbHZOMYftlSpyuarEvJzy'