Editing: secrets.py
"""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/ """ __all__ = ['choice', 'randbelow', 'randbits', 'SystemRandom', 'token_bytes', 'token_hex', 'token_urlsafe', 'compare_digest', ] import base64 import binascii from hmac import compare_digest from random import SystemRandom _sysrand = SystemRandom() randbits = _sysrand.getrandbits choice = _sysrand.choice def randbelow(exclusive_upper_bound): """Return a random int in the range [0, n).""" if exclusive_upper_bound <= 0: raise ValueError("Upper bound must be positive.") return _sysrand._randbelow(exclusive_upper_bound) DEFAULT_ENTROPY = 32 # number of bytes to return by default def token_bytes(nbytes=None): """Return a random byte string containing *nbytes* bytes. If *nbytes* is ``None`` or not supplied, a reasonable default is used. >>> token_bytes(16) #doctest:+SKIP b'\\xebr\\x17D*t\\xae\\xd4\\xe3S\\xb6\\xe2\\xebP1\\x8b' """ if nbytes is None: nbytes = DEFAULT_ENTROPY return _sysrand.randbytes(nbytes) def token_hex(nbytes=None): """Return a random text string, in hexadecimal. The string has *nbytes* random bytes, each byte converted to two hex digits. If *nbytes* is ``None`` or not supplied, a reasonable default is used. >>> token_hex(16) #doctest:+SKIP 'f9bf78b9a18ce6d46a0cd2b0b86df9da' """ return binascii.hexlify(token_bytes(nbytes)).decode('ascii') def token_urlsafe(nbytes=None): """Return a random URL-safe text string, in Base64 encoding. The string has *nbytes* random bytes. If *nbytes* is ``None`` or not supplied, a reasonable default is used. >>> token_urlsafe(16) #doctest:+SKIP 'Drmhze6EPcv0fN_81Bj-nA' """ tok = token_bytes(nbytes) return base64.urlsafe_b64encode(tok).rstrip(b'=').decode('ascii')
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