Random Key in python

random_key.py

import base64
import random
from binascii import unhexlify, b2a_base64


def long_to_bytes (val):
    """
    Use :ref:`string formatting` and :func:`~binascii.unhexlify` to
    convert ``val``, a :func:`long`, to a byte :func:`str`.

    :param long val: The value to pack

    Using :ref:`string formatting` lets us use Python's C innards.
    """

    # one (1) hex digit per four (4) bits
    width = val.bit_length()

    # unhexlify wants an even multiple of eight (8) bits, but we don't
    # want more digits than we need (hence the ternary-ish 'or')
    width += 8 - ((width % 8) or 8)

    # format width specifier: four (4) bits per hex digit
    fmt = '%%0%dx' % (width // 4)

    # prepend zero (0) to the width, to zero-pad the output
    return unhexlify(fmt % val)


def generate_uid(bitlength=120):
    rand = random.getrandbits(bitlength)
    return base64.urlsafe_b64encode(long_to_bytes(rand))

def faster_generate_uid(bitlength=120):
    rand = random.getrandbits(bitlength)
    s = b2a_base64(long_to_bytes(rand))
    return s.replace('+', '-').replace('/', '_')




"""
Entropy provided by a Base62 string:
 2 chars:  11 bits
 4 chars:  23 bits
 6 chars:  35 bits
 8 chars:  47 bits
10 chars:  59 bits
12 chars:  71 bits
14 chars:  83 bits
16 chars:  95 bits
18 chars: 107 bits
20 chars: 119 bits
22 chars: 130 bits
24 chars: 142 bits
26 chars: 154 bits
28 chars: 166 bits
30 chars: 178 bits
32 chars: 190 bits
34 chars: 202 bits
36 chars: 214 bits
38 chars: 226 bits
40 chars: 238 bits
42 chars: 250 bits
44 chars: 261 bits
46 chars: 273 bits
48 chars: 285 bits
50 chars: 297 bits
52 chars: 309 bits
54 chars: 321 bits
56 chars: 333 bits
58 chars: 345 bits
60 chars: 357 bits
62 chars: 369 bits
64 chars: 381 bits
"""

base62_chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'

def make_base62_uid(length=16):

    return ''.join([base62_chars[int(random.random() * 62)] for _ in range(length)])


def make_base62_uid_and_integer(length=10):
    """A length of 10 would produce 8 bytes integers"""
    seq =[int(random.random() * 62) for _ in range(length)]
    value = 0
    for e in seq:
        value = value * 62 + e
    return (''.join([base62_chars[e] for e in seq]), value)

chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
length = 62

def uid():
    return ''.join([chars[int(random.random() * length)] for _ in range(16)])

In [65]: uid()
Out[65]: 'hZJAmloh6JMbcwKm'

In [66]: %timeit uid()
100000 loops, best of 3: 3.48 µs per loop