Reference client for Bitmessage: a P2P encrypted decentralised communication protocol:
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"""
Convenience functions for random operations. Not suitable for security / cryptography operations
"""
import os
import random
from pyelliptic.openssl import OpenSSL
NoneType = type(None)
def seed():
"""Initialize random number generator"""
random.seed()
def randomBytes(n):
"""Method randomBytes."""
try:
return os.urandom(n)
except NotImplementedError:
return OpenSSL.rand(n)
def randomshuffle(population):
"""Method randomShuffle.
shuffle the sequence x in place.
shuffles the elements in list in place,
so they are in a random order.
As Shuffle will alter data in-place,
so its input must be a mutable sequence.
In contrast, sample produces a new list
and its input can be much more varied
(tuple, string, xrange, bytearray, set, etc)
"""
random.shuffle(population)
def randomsample(population, k):
"""Method randomSample.
return a k length list of unique elements
chosen from the population sequence.
Used for random sampling
without replacement, its called
partial shuffle.
"""
return random.sample(population, k)
def randomrandrange(x, y=None):
"""Method randomRandrange.
return a randomly selected element from
range(start, stop). This is equivalent to
choice(range(start, stop)),
but doesnt actually build a range object.
"""
if isinstance(y, NoneType):
return random.randrange(x) # nosec
else:
return random.randrange(x, y) # nosec
def randomchoice(population):
"""Method randomchoice.
Return a random element from the non-empty
sequence seq. If seq is empty, raises
IndexError.
"""
return random.choice(population) # nosec