How to generate a number of n-bit in length using python? [duplicate]

Question

Looking at the various random functions in the standard library, there isn't a way to generate numbers of n-bit length long.

Is there any efficient function I can use to accomplish this?

Answer 1

Yes there is:

>>> import random
>>> random.getrandbits(1)
0L
>>> random.getrandbits(100)
31456252575598781139680104123L
>>> help(random.getrandbits)
Help on built-in function getrandbits:

getrandbits(...)
    getrandbits(k) -> x.  Generates a long int with k random bits.

From the docs:

random.getrandbits(k)
Returns a python long int with k random bits. This method is supplied with the MersenneTwister generator and some other generators may also provide it as an optional part of the API. When available, getrandbits() enables randrange() to handle arbitrarily large ranges.