Generate password in python

Question

I\'dl like to generate some alphanumeric passwords in python. Some possible ways are:

import string
from random import sample, choice
chars = string.letters          


        

Answer 1

I wrote a script with my preferences, which mostly are concerned with avoiding mistakes when transcribing and remembering. (For example: remove somewhat ambiguous and no repeated characters.)

import optparse
import os
import random
import sys

DEFAULT_CHARS = "234679ADEFGHJKLMNPRTUWabdefghijkmnpqrstuwy"
DEFAULT_LEN = 18

def choices(options, length, choice=random.choice):
  return (choice(options) for _ in xrange(length))

def choices_non_repeated(options, length, choice=random.choice):
  assert len(options) > 1
  last = choice(options)
  count = 0
  while count < length:
    yield last
    count += 1

    while True:
      value = choice(options)
      if value != last:
        last = value
        break

def main(args):
  op = optparse.OptionParser(add_help_option=False)
  op.add_option("--help", action="help",
    help="show help message and exit")
  op.add_option("-b", "--bare", action="store_true", default=False,
    help="print passwords without trailing newline")
  op.add_option("-c", "--chars", metavar="SET", nargs=1, default=DEFAULT_CHARS,
    help="character set to use (default: %default)")
  op.add_option("--repeat", action="store_true", default=False,
    help="allow repetition")
  op.add_option("-l", "--len", dest="max", nargs=1, type="int", default=DEFAULT_LEN,
    help="max length (default: %default)")
  op.add_option("--min", nargs=1, type="int", default=None,
    help="min length (defaults to max)")
  op.add_option("-n", "--count", nargs=1, type="int", default=None,
    help="number of passwords to generate (default: %default)")
  op.add_option("--cols", type="int", default=None,
    help="number of columns to use")
  opts, args = op.parse_args(args)
  if args:
    op.error("unknown arguments")

  if os.isatty(sys.stdin.fileno()) and (
    opts.count is None and opts.cols is None
    and not opts.bare
  ):
    opts.cols = 80 // (opts.max + 1)
    opts.count = opts.cols * 25
  else:
    if opts.count is None:
      opts.count = 1
    if opts.cols is None:
      opts.cols = 1

  if opts.bare and opts.cols != 1:
    op.error("bare output requires --cols=1")

  if opts.min == None:
    opts.min = opts.max

  if any(x < 1 for x in [opts.cols, opts.count, opts.min, opts.max]):
    op.error("values must be >= 1")

  choices_func = choices_non_repeated
  if opts.repeat:
    choices_func = choices
  elif len(set(opts.chars)) < 2:
    op.error("must allow repetition or provide a longer character set")
    return "op.error shouldn't return"

  col = 0
  for _ in xrange(opts.count):
    length = random.randint(opts.min, opts.max)
    password = "".join(choices_func(opts.chars, length))
    sys.stdout.write(password)
    if not opts.bare:
      col += 1
      if col == opts.cols:
        sys.stdout.write("\n")
        col = 0
      else:
        sys.stdout.write(" ")


if __name__ == "__main__":
  sys.exit(main(sys.argv[1:]))

Answer 2

Here in the line 9 of above coding:

return (choice(options) for _ in xrange(length))

Actually the xrange is not defined, so the correct coding for this is:

return (choice(options) for _ in range(length))

Same in 76 line too.

Answer 3

You may want to use map instead of list comprehensions:

''.join(map(lambda x: random.choice(chars), range(length)))