"""Generate cryptographically strong pseudo-random numbers suitable for
managing secrets such as account authentication, tokens, and similar.

See PEP 506 for more information.
https://www.python.org/dev/peps/pep-0506/

Amit nem hasznalok belole azt kivettem!
Eredeti forras: https://raw.githubusercontent.com/python/cpython/3.7/Lib/secrets.py

"""

__all__ = ['choice', 'randbelow', 'randbits', 'SystemRandom',
           'token_bytes', 'token_hex', 'token_urlsafe',
           'compare_digest',
           ]


import base64
import binascii
import os

from hmac import compare_digest
from random import SystemRandom

_sysrand = SystemRandom()

randbits = _sysrand.getrandbits
choice = _sysrand.choice

DEFAULT_ENTROPY = 64  # number of bytes to return by default

def token_bytes(nbytes=None):
    """Return a random byte string containing *nbytes* bytes.
    >>> token_bytes(16)  #doctest:+SKIP
    b'\\xebr\\x17D*t\\xae\\xd4\\xe3S\\xb6\\xe2\\xebP1\\x8b'"""
    if nbytes is None:
        nbytes = DEFAULT_ENTROPY
    return os.urandom(nbytes)


def token_hex(nbytes=None):
    """Return a random text string, in hexadecimal.
    >>> token_hex(16)  #doctest:+SKIP
    'f9bf78b9a18ce6d46a0cd2b0b86df9da'"""
    return binascii.hexlify(token_bytes(nbytes)).decode('ascii')