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Diffstat (limited to 'Doc/library/hashlib.rst')
| -rw-r--r-- | Doc/library/hashlib.rst | 79 |
1 files changed, 70 insertions, 9 deletions
diff --git a/Doc/library/hashlib.rst b/Doc/library/hashlib.rst index a2e96ca..2cb3c78 100644 --- a/Doc/library/hashlib.rst +++ b/Doc/library/hashlib.rst @@ -44,8 +44,8 @@ Hash algorithms --------------- There is one constructor method named for each type of :dfn:`hash`. All return -a hash object with the same simple interface. For example: use :func:`sha1` to -create a SHA1 hash object. You can now feed this object with :term:`bytes-like +a hash object with the same simple interface. For example: use :func:`sha256` to +create a SHA-256 hash object. You can now feed this object with :term:`bytes-like objects <bytes-like object>` (normally :class:`bytes`) using the :meth:`update` method. At any point you can ask it for the :dfn:`digest` of the concatenation of the data fed to it so far using the :meth:`digest` or @@ -64,21 +64,33 @@ concatenation of the data fed to it so far using the :meth:`digest` or .. index:: single: OpenSSL; (use in module hashlib) Constructors for hash algorithms that are always present in this module are -:func:`md5`, :func:`sha1`, :func:`sha224`, :func:`sha256`, :func:`sha384`, -and :func:`sha512`. Additional algorithms may also be available depending upon -the OpenSSL library that Python uses on your platform. +:func:`sha1`, :func:`sha224`, :func:`sha256`, :func:`sha384`, +:func:`sha512`, :func:`blake2b`, and :func:`blake2s`. +:func:`md5` is normally available as well, though it +may be missing if you are using a rare "FIPS compliant" build of Python. +Additional algorithms may also be available depending upon the OpenSSL +library that Python uses on your platform. On most platforms the +:func:`sha3_224`, :func:`sha3_256`, :func:`sha3_384`, :func:`sha3_512`, +:func:`shake_128`, :func:`shake_256` are also available. + +.. versionadded:: 3.6 + SHA3 (Keccak) and SHAKE constructors :func:`sha3_224`, :func:`sha3_256`, + :func:`sha3_384`, :func:`sha3_512`, :func:`shake_128`, :func:`shake_256`. + +.. versionadded:: 3.6 + :func:`blake2b` and :func:`blake2s` were added. For example, to obtain the digest of the byte string ``b'Nobody inspects the spammish repetition'``:: >>> import hashlib - >>> m = hashlib.md5() + >>> m = hashlib.sha256() >>> m.update(b"Nobody inspects") >>> m.update(b" the spammish repetition") >>> m.digest() - b'\xbbd\x9c\x83\xdd\x1e\xa5\xc9\xd9\xde\xc9\xa1\x8d\xf0\xff\xe9' + b'\x03\x1e\xdd}Ae\x15\x93\xc5\xfe\\\x00o\xa5u+7\xfd\xdf\xf7\xbcN\x84:\xa6\xaf\x0c\x95\x0fK\x94\x06' >>> m.digest_size - 16 + 32 >>> m.block_size 64 @@ -107,7 +119,9 @@ Hashlib provides the following constant attributes: .. data:: algorithms_guaranteed A set containing the names of the hash algorithms guaranteed to be supported - by this module on all platforms. + by this module on all platforms. Note that 'md5' is in this list despite + some upstream vendors offering an odd "FIPS compliant" Python build that + excludes it. .. versionadded:: 3.2 @@ -181,6 +195,28 @@ A hash object has the following methods: compute the digests of data sharing a common initial substring. +SHAKE variable length digests +----------------------------- + +The :func:`shake_128` and :func:`shake_256` algorithms provide variable +length digests with length_in_bits//2 up to 128 or 256 bits of security. +As such, their digest methods require a length. Maximum length is not limited +by the SHAKE algorithm. + +.. method:: shake.digest(length) + + Return the digest of the data passed to the :meth:`update` method so far. + This is a bytes object of size ``length`` which may contain bytes in + the whole range from 0 to 255. + + +.. method:: shake.hexdigest(length) + + Like :meth:`digest` except the digest is returned as a string object of + double length, containing only hexadecimal digits. This may be used to + exchange the value safely in email or other non-binary environments. + + Key derivation -------------- @@ -221,6 +257,29 @@ include a `salt <https://en.wikipedia.org/wiki/Salt_%28cryptography%29>`_. Python implementation uses an inline version of :mod:`hmac`. It is about three times slower and doesn't release the GIL. +.. function:: scrypt(password, *, salt, n, r, p, maxmem=0, dklen=64) + + The function provides scrypt password-based key derivation function as + defined in :rfc:`7914`. + + *password* and *salt* must be bytes-like objects. Applications and + libraries should limit *password* to a sensible length (e.g. 1024). *salt* + should be about 16 or more bytes from a proper source, e.g. :func:`os.urandom`. + + *n* is the CPU/Memory cost factor, *r* the block size, *p* parallelization + factor and *maxmem* limits memory (OpenSSL 1.1.0 defaults to 32 MB). + *dklen* is the length of the derived key. + + Availability: OpenSSL 1.1+ + + .. versionadded:: 3.6 + + +BLAKE2 +------ + +BLAKE2 takes additional arguments, see :ref:`hashlib-blake2`. + .. seealso:: @@ -230,6 +289,8 @@ include a `salt <https://en.wikipedia.org/wiki/Salt_%28cryptography%29>`_. Module :mod:`base64` Another way to encode binary hashes for non-binary environments. + See :ref:`hashlib-blake2`. + http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf The FIPS 180-2 publication on Secure Hash Algorithms. |