Current File : //var/opt/nydus/ops/oscrypto/_rand.py
# coding: utf-8
from __future__ import unicode_literals, division, absolute_import, print_function
import os
from ._errors import pretty_message
from ._types import type_name, int_types
__all__ = [
'rand_bytes',
]
def rand_bytes(length):
"""
Returns a number of random bytes suitable for cryptographic purposes
:param length:
The desired number of bytes
:raises:
ValueError - when any of the parameters contain an invalid value
TypeError - when any of the parameters are of the wrong type
OSError - when an error is returned by OpenSSL
:return:
A byte string
"""
if not isinstance(length, int_types):
raise TypeError(pretty_message(
'''
length must be an integer, not %s
''',
type_name(length)
))
if length < 1:
raise ValueError('length must be greater than 0')
if length > 1024:
raise ValueError('length must not be greater than 1024')
return os.urandom(length)
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