import random
DEFAULT_PASSWORD_SYMBOLS = ('23456789', # Removed: 0,1
'ABCDEFGHJKLMNPQRSTUVWXYZ', # Removed: I, O
'abcdefghijkmnopqrstuvwxyz') # Removed: l
def generate_password(length=None, symbolgroups=DEFAULT_PASSWORD_SYMBOLS):
"""Generate a random password from the supplied symbol groups.
At least one symbol from each group will be included. Unpredictable
results if length is less than the number of symbol groups.
Believed to be reasonably secure (with a reasonable password length!)
"""
if length is None:
length = 12
r = random.SystemRandom()
# NOTE(jerdfelt): Some password policies require at least one character
# from each group of symbols, so start off with one random character
# from each symbol group
password = [r.choice(s) for s in symbolgroups]
# If length < len(symbolgroups), the leading characters will only
# be from the first length groups. Try our best to not be predictable
# by shuffling and then truncating.
r.shuffle(password)
password = password[:length]
length -= len(password)
# then fill with random characters from all symbol groups
symbols = ''.join(symbolgroups)
password.extend([r.choice(symbols) for _i in range(length)])
# finally shuffle to ensure first x characters aren't from a
# predictable group
r.shuffle(password)
return ''.join(password)
ps= generate_password()
其中SystemRandom会产生一个平台相关的随机数生成器，
choice 方法会从给定的序列里取出一个随机element
shuffle 方法会打乱给定的list
