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author | Steven D'Aprano <steve@pearwood.info> | 2016-04-17 03:13:36 (GMT) |
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committer | Steven D'Aprano <steve@pearwood.info> | 2016-04-17 03:13:36 (GMT) |
commit | 4ad465424a6ab3f76b378d898e1bf06ec0976c26 (patch) | |
tree | 148eb085515c2f2b759436e2cf448022c5e78c2a /Lib/secrets.py | |
parent | 151f5d5971ad3c19e0c6635e4ff0bbbad4cd1a82 (diff) | |
download | cpython-4ad465424a6ab3f76b378d898e1bf06ec0976c26.zip cpython-4ad465424a6ab3f76b378d898e1bf06ec0976c26.tar.gz cpython-4ad465424a6ab3f76b378d898e1bf06ec0976c26.tar.bz2 |
Shorten secrets module docstring, add function docstrings.
Diffstat (limited to 'Lib/secrets.py')
-rw-r--r-- | Lib/secrets.py | 106 |
1 files changed, 30 insertions, 76 deletions
diff --git a/Lib/secrets.py b/Lib/secrets.py index e4e9714..27fa450 100644 --- a/Lib/secrets.py +++ b/Lib/secrets.py @@ -1,84 +1,9 @@ """Generate cryptographically strong pseudo-random numbers suitable for managing secrets such as account authentication, tokens, and similar. -See PEP 506 for more information. +See PEP 506 for more information. https://www.python.org/dev/peps/pep-0506/ - -Random numbers -============== - -The ``secrets`` module provides the following pseudo-random functions, based -on SystemRandom, which in turn uses the most secure source of randomness your -operating system provides. - - - choice(sequence) - Choose a random element from a non-empty sequence. - - randbelow(n) - Return a random int in the range [0, n). - - randbits(k) - Generates an int with k random bits. - - SystemRandom - Class for generating random numbers using sources provided by - the operating system. See the ``random`` module for documentation. - - -Token functions -=============== - -The ``secrets`` module provides a number of functions for generating secure -tokens, suitable for applications such as password resets, hard-to-guess -URLs, and similar. All the ``token_*`` functions take an optional single -argument specifying the number of bytes of randomness to use. If that is -not given, or is ``None``, a reasonable default is used. That default is -subject to change at any time, including during maintenance releases. - - - token_bytes(nbytes=None) - Return a random byte-string containing ``nbytes`` number of bytes. - - >>> secrets.token_bytes(16) #doctest:+SKIP - b'\\xebr\\x17D*t\\xae\\xd4\\xe3S\\xb6\\xe2\\xebP1\\x8b' - - - token_hex(nbytes=None) - Return a random text-string, in hexadecimal. The string has ``nbytes`` - random bytes, each byte converted to two hex digits. - - >>> secrets.token_hex(16) #doctest:+SKIP - 'f9bf78b9a18ce6d46a0cd2b0b86df9da' - - token_urlsafe(nbytes=None) - Return a random URL-safe text-string, containing ``nbytes`` random - bytes. On average, each byte results in approximately 1.3 characters - in the final result. - - >>> secrets.token_urlsafe(16) #doctest:+SKIP - 'Drmhze6EPcv0fN_81Bj-nA' - - -(The examples above assume Python 3. In Python 2, byte-strings will display -using regular quotes ``''`` with no prefix, and text-strings will have a -``u`` prefix.) - - -Other functions -=============== - - compare_digest(a, b) - Return True if strings a and b are equal, otherwise False. - Performs the equality comparison in such a way as to reduce the - risk of timing attacks. - - See http://codahale.com/a-lesson-in-timing-attacks/ for a - discussion on how timing attacks against ``==`` can reveal - secrets from your application. - - """ __all__ = ['choice', 'randbelow', 'randbits', 'SystemRandom', @@ -100,18 +25,47 @@ randbits = _sysrand.getrandbits choice = _sysrand.choice def randbelow(exclusive_upper_bound): + """Return a random int in the range [0, n).""" 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 os.urandom(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') |