hashlib.rst

:mod:`hashlib` --- Secure hashes and message digests

.. module:: hashlib
   :synopsis: Secure hash and message digest algorithms.

.. moduleauthor:: Gregory P. Smith <greg@krypto.org>

.. sectionauthor:: Gregory P. Smith <greg@krypto.org>

Source code: :source:`Lib/hashlib.py`

.. index::
   single: message digest, MD5
   single: secure hash algorithm, SHA1, SHA224, SHA256, SHA384, SHA512

.. testsetup::

   import hashlib

---

This module implements a common interface to many different secure hash and message digest algorithms. Included are the FIPS secure hash algorithms SHA1, SHA224, SHA256, SHA384, and SHA512 (defined in FIPS 180-2) as well as RSA's MD5 algorithm (defined in internet RFC 1321). The terms "secure hash" and "message digest" are interchangeable. Older algorithms were called message digests. The modern term is secure hash.

Note

If you want the adler32 or crc32 hash functions, they are available in the :mod:`zlib` module.

Warning

Some algorithms have known hash collision weaknesses, refer to the "See also" section at the end.

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:`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 :meth:`hexdigest` methods.

Note

For better multithreading performance, the Python :term:`GIL` is released for data larger than 2047 bytes at object creation or on update.

Note

Feeding string objects into :meth:`update` is not supported, as hashes work on bytes, not on characters.

.. index:: single: OpenSSL; (use in module hashlib)

Constructors for hash algorithms that are always present in this module are :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 or blocked 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.

.. versionchanged:: 3.9
   All hashlib constructors take a keyword-only argument *usedforsecurity*
   with default value ``True``. A false value allows the use of insecure and
   blocked hashing algorithms in restricted environments. ``False`` indicates
   that the hashing algorithm is not used in a security context, e.g. as a
   non-cryptographic one-way compression function.

   Hashlib now uses SHA3 and SHAKE from OpenSSL 1.1.1 and newer.

For example, to obtain the digest of the byte string b"Nobody inspects the spammish repetition":

>>> import hashlib
>>> m = hashlib.sha256()
>>> m.update(b"Nobody inspects")
>>> m.update(b" the spammish repetition")
>>> m.digest()
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.hexdigest()
'031edd7d41651593c5fe5c006fa5752b37fddff7bc4e843aa6af0c950f4b9406'

More condensed:

>>> hashlib.sha256(b"Nobody inspects the spammish repetition").hexdigest()
'031edd7d41651593c5fe5c006fa5752b37fddff7bc4e843aa6af0c950f4b9406'

.. function:: new(name[, data], *, usedforsecurity=True)

   Is a generic constructor that takes the string *name* of the desired
   algorithm as its first parameter.  It also exists to allow access to the
   above listed hashes as well as any other algorithms that your OpenSSL
   library may offer.  The named constructors are much faster than :func:`new`
   and should be preferred.

Using :func:`new` with an algorithm provided by OpenSSL:

>>> h = hashlib.new('sha256')
>>> h.update(b"Nobody inspects the spammish repetition")
>>> h.hexdigest()
'031edd7d41651593c5fe5c006fa5752b37fddff7bc4e843aa6af0c950f4b9406'

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.  Note that 'md5' is in this list despite
   some upstream vendors offering an odd "FIPS compliant" Python build that
   excludes it.

   .. versionadded:: 3.2

.. data:: algorithms_available

   A set containing the names of the hash algorithms that are available in the
   running Python interpreter.  These names will be recognized when passed to
   :func:`new`.  :attr:`algorithms_guaranteed` will always be a subset.  The
   same algorithm may appear multiple times in this set under different names
   (thanks to OpenSSL).

   .. versionadded:: 3.2

The following values are provided as constant attributes of the hash objects returned by the constructors:

.. data:: hash.digest_size

   The size of the resulting hash in bytes.

.. data:: hash.block_size

   The internal block size of the hash algorithm in bytes.

A hash object has the following attributes:

.. attribute:: hash.name

   The canonical name of this hash, always lowercase and always suitable as a
   parameter to :func:`new` to create another hash of this type.

   .. versionchanged:: 3.4
      The name attribute has been present in CPython since its inception, but
      until Python 3.4 was not formally specified, so may not exist on some
      platforms.

A hash object has the following methods:

.. method:: hash.update(data)

   Update the hash object with the :term:`bytes-like object`.
   Repeated calls are equivalent to a single call with the
   concatenation of all the arguments: ``m.update(a); m.update(b)`` is
   equivalent to ``m.update(a+b)``.

   .. versionchanged:: 3.1
      The Python GIL is released to allow other threads to run while hash
      updates on data larger than 2047 bytes is taking place when using hash
      algorithms supplied by OpenSSL.

.. method:: hash.digest()

   Return the digest of the data passed to the :meth:`update` method so far.
   This is a bytes object of size :attr:`digest_size` which may contain bytes in
   the whole range from 0 to 255.

.. method:: hash.hexdigest()

   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.

.. method:: hash.copy()

   Return a copy ("clone") of the hash object.  This can be used to efficiently
   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.

File hashing

The hashlib module provides a helper function for efficient hashing of a file or file-like object.

.. function:: file_digest(fileobj, digest, /)

   Return a digest object that has been updated with contents of file object.

   *fileobj* must be a file-like object opened for reading in binary mode.
   It accepts file objects from  builtin :func:`open`, :class:`~io.BytesIO`
   instances, SocketIO objects from :meth:`socket.socket.makefile`, and
   similar. The function may bypass Python's I/O and use the file descriptor
   from :meth:`~io.IOBase.fileno` directly. *fileobj* must be assumed to be
   in an unknown state after this function returns or raises. It is up to
   the caller to close *fileobj*.

   *digest* must either be a hash algorithm name as a *str*, a hash
   constructor, or a callable that returns a hash object.

   Example:

      >>> import io, hashlib, hmac
      >>> with open(hashlib.__file__, "rb") as f:
      ...     digest = hashlib.file_digest(f, "sha256")
      ...
      >>> digest.hexdigest()  # doctest: +ELLIPSIS
      '...'

      >>> buf = io.BytesIO(b"somedata")
      >>> mac1 = hmac.HMAC(b"key", digestmod=hashlib.sha512)
      >>> digest = hashlib.file_digest(buf, lambda: mac1)

      >>> digest is mac1
      True
      >>> mac2 = hmac.HMAC(b"key", b"somedata", digestmod=hashlib.sha512)
      >>> mac1.digest() == mac2.digest()
      True

   .. versionadded:: 3.11

Key derivation

Key derivation and key stretching algorithms are designed for secure password hashing. Naive algorithms such as sha1(password) are not resistant against brute-force attacks. A good password hashing function must be tunable, slow, and include a salt.

.. function:: pbkdf2_hmac(hash_name, password, salt, iterations, dklen=None)

   The function provides PKCS#5 password-based key derivation function 2. It
   uses HMAC as pseudorandom function.

   The string *hash_name* is the desired name of the hash digest algorithm for
   HMAC, e.g. 'sha1' or 'sha256'. *password* and *salt* are interpreted as
   buffers of bytes. 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`.

   The number of *iterations* should be chosen based on the hash algorithm and
   computing power. As of 2022, hundreds of thousands of iterations of SHA-256
   are suggested. For rationale as to why and how to choose what is best for
   your application, read *Appendix A.2.2* of NIST-SP-800-132_. The answers
   on the `stackexchange pbkdf2 iterations question`_ explain in detail.

   *dklen* is the length of the derived key. If *dklen* is ``None`` then the
   digest size of the hash algorithm *hash_name* is used, e.g. 64 for SHA-512.

   >>> from hashlib import pbkdf2_hmac
   >>> our_app_iters = 500_000  # Application specific, read above.
   >>> dk = pbkdf2_hmac('sha256', b'password', b'bad salt' * 2, our_app_iters)
   >>> dk.hex()
   '15530bba69924174860db778f2c6f8104d3aaf9d26241840c8c4a641c8d000a9'

   Function only available when Python is compiled with OpenSSL.

   .. versionadded:: 3.4

   .. versionchanged:: 3.12
      Function now only available when Python is built with OpenSSL. The slow
      pure Python implementation has been removed.

.. 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 :term:`bytes-like objects
   <bytes-like object>`.  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 MiB).
   *dklen* is the length of the derived key.

   .. versionadded:: 3.6

BLAKE2

.. sectionauthor:: Dmitry Chestnykh

.. index::
   single: blake2b, blake2s

BLAKE2 is a cryptographic hash function defined in RFC 7693 that comes in two flavors:

• BLAKE2b, optimized for 64-bit platforms and produces digests of any size between 1 and 64 bytes,
• BLAKE2s, optimized for 8- to 32-bit platforms and produces digests of any size between 1 and 32 bytes.

BLAKE2 supports keyed mode (a faster and simpler replacement for HMAC), salted hashing, personalization, and tree hashing.

Hash objects from this module follow the API of standard library's :mod:`hashlib` objects.

Creating hash objects

New hash objects are created by calling constructor functions:

.. function:: blake2b(data=b'', *, digest_size=64, key=b'', salt=b'', \
                person=b'', fanout=1, depth=1, leaf_size=0, node_offset=0,  \
                node_depth=0, inner_size=0, last_node=False, \
                usedforsecurity=True)

.. function:: blake2s(data=b'', *, digest_size=32, key=b'', salt=b'', \
                person=b'', fanout=1, depth=1, leaf_size=0, node_offset=0,  \
                node_depth=0, inner_size=0, last_node=False, \
                usedforsecurity=True)

These functions return the corresponding hash objects for calculating BLAKE2b or BLAKE2s. They optionally take these general parameters:

• data: initial chunk of data to hash, which must be :term:`bytes-like object`. It can be passed only as positional argument.
• digest_size: size of output digest in bytes.
• key: key for keyed hashing (up to 64 bytes for BLAKE2b, up to 32 bytes for BLAKE2s).
• salt: salt for randomized hashing (up to 16 bytes for BLAKE2b, up to 8 bytes for BLAKE2s).
• person: personalization string (up to 16 bytes for BLAKE2b, up to 8 bytes for BLAKE2s).

The following table shows limits for general parameters (in bytes):

Hash	digest_size	len(key)	len(salt)	len(person)
BLAKE2b	64	64	16	16
BLAKE2s	32	32	8	8

Note

BLAKE2 specification defines constant lengths for salt and personalization parameters, however, for convenience, this implementation accepts byte strings of any size up to the specified length. If the length of the parameter is less than specified, it is padded with zeros, thus, for example, b'salt' and b'salt\x00' is the same value. (This is not the case for key.)

These sizes are available as module constants described below.

Constructor functions also accept the following tree hashing parameters:

• fanout: fanout (0 to 255, 0 if unlimited, 1 in sequential mode).
• depth: maximal depth of tree (1 to 255, 255 if unlimited, 1 in sequential mode).
• leaf_size: maximal byte length of leaf (0 to 2**32-1, 0 if unlimited or in sequential mode).
• node_offset: node offset (0 to 2**64-1 for BLAKE2b, 0 to 2**48-1 for BLAKE2s, 0 for the first, leftmost, leaf, or in sequential mode).
• node_depth: node depth (0 to 255, 0 for leaves, or in sequential mode).
• inner_size: inner digest size (0 to 64 for BLAKE2b, 0 to 32 for BLAKE2s, 0 in sequential mode).
• last_node: boolean indicating whether the processed node is the last one (False for sequential mode).

See section 2.10 in BLAKE2 specification for comprehensive review of tree hashing.

Constants

.. data:: blake2b.SALT_SIZE

.. data:: blake2s.SALT_SIZE

Salt length (maximum length accepted by constructors).

.. data:: blake2b.PERSON_SIZE

.. data:: blake2s.PERSON_SIZE

Personalization string length (maximum length accepted by constructors).

.. data:: blake2b.MAX_KEY_SIZE

.. data:: blake2s.MAX_KEY_SIZE

Maximum key size.

.. data:: blake2b.MAX_DIGEST_SIZE

.. data:: blake2s.MAX_DIGEST_SIZE

Maximum digest size that the hash function can output.

Examples

Simple hashing

To calculate hash of some data, you should first construct a hash object by calling the appropriate constructor function (:func:`blake2b` or :func:`blake2s`), then update it with the data by calling :meth:`update` on the object, and, finally, get the digest out of the object by calling :meth:`digest` (or :meth:`hexdigest` for hex-encoded string).

>>> from hashlib import blake2b
>>> h = blake2b()
>>> h.update(b'Hello world')
>>> h.hexdigest()
'6ff843ba685842aa82031d3f53c48b66326df7639a63d128974c5c14f31a0f33343a8c65551134ed1ae0f2b0dd2bb495dc81039e3eeb0aa1bb0388bbeac29183'

As a shortcut, you can pass the first chunk of data to update directly to the constructor as the positional argument:

>>> from hashlib import blake2b
>>> blake2b(b'Hello world').hexdigest()
'6ff843ba685842aa82031d3f53c48b66326df7639a63d128974c5c14f31a0f33343a8c65551134ed1ae0f2b0dd2bb495dc81039e3eeb0aa1bb0388bbeac29183'

You can call :meth:`hash.update` as many times as you need to iteratively update the hash:

>>> from hashlib import blake2b
>>> items = [b'Hello', b' ', b'world']
>>> h = blake2b()
>>> for item in items:
...     h.update(item)
>>> h.hexdigest()
'6ff843ba685842aa82031d3f53c48b66326df7639a63d128974c5c14f31a0f33343a8c65551134ed1ae0f2b0dd2bb495dc81039e3eeb0aa1bb0388bbeac29183'

Using different digest sizes

BLAKE2 has configurable size of digests up to 64 bytes for BLAKE2b and up to 32 bytes for BLAKE2s. For example, to replace SHA-1 with BLAKE2b without changing the size of output, we can tell BLAKE2b to produce 20-byte digests:

>>> from hashlib import blake2b
>>> h = blake2b(digest_size=20)
>>> h.update(b'Replacing SHA1 with the more secure function')
>>> h.hexdigest()
'd24f26cf8de66472d58d4e1b1774b4c9158b1f4c'
>>> h.digest_size
20
>>> len(h.digest())
20

Hash objects with different digest sizes have completely different outputs (shorter hashes are not prefixes of longer hashes); BLAKE2b and BLAKE2s produce different outputs even if the output length is the same:

>>> from hashlib import blake2b, blake2s
>>> blake2b(digest_size=10).hexdigest()
'6fa1d8fcfd719046d762'
>>> blake2b(digest_size=11).hexdigest()
'eb6ec15daf9546254f0809'
>>> blake2s(digest_size=10).hexdigest()
'1bf21a98c78a1c376ae9'
>>> blake2s(digest_size=11).hexdigest()
'567004bf96e4a25773ebf4'

Keyed hashing

Keyed hashing can be used for authentication as a faster and simpler replacement for Hash-based message authentication code (HMAC). BLAKE2 can be securely used in prefix-MAC mode thanks to the indifferentiability property inherited from BLAKE.

This example shows how to get a (hex-encoded) 128-bit authentication code for message b'message data' with key b'pseudorandom key':

>>> from hashlib import blake2b
>>> h = blake2b(key=b'pseudorandom key', digest_size=16)
>>> h.update(b'message data')
>>> h.hexdigest()
'3d363ff7401e02026f4a4687d4863ced'

As a practical example, a web application can symmetrically sign cookies sent to users and later verify them to make sure they weren't tampered with:

>>> from hashlib import blake2b
>>> from hmac import compare_digest
>>>
>>> SECRET_KEY = b'pseudorandomly generated server secret key'
>>> AUTH_SIZE = 16
>>>
>>> def sign(cookie):
...     h = blake2b(digest_size=AUTH_SIZE, key=SECRET_KEY)
...     h.update(cookie)
...     return h.hexdigest().encode('utf-8')
>>>
>>> def verify(cookie, sig):
...     good_sig = sign(cookie)
...     return compare_digest(good_sig, sig)
>>>
>>> cookie = b'user-alice'
>>> sig = sign(cookie)
>>> print("{0},{1}".format(cookie.decode('utf-8'), sig))
user-alice,b'43b3c982cf697e0c5ab22172d1ca7421'
>>> verify(cookie, sig)
True
>>> verify(b'user-bob', sig)
False
>>> verify(cookie, b'0102030405060708090a0b0c0d0e0f00')
False

Even though there's a native keyed hashing mode, BLAKE2 can, of course, be used in HMAC construction with :mod:`hmac` module:

>>> import hmac, hashlib
>>> m = hmac.new(b'secret key', digestmod=hashlib.blake2s)
>>> m.update(b'message')
>>> m.hexdigest()
'e3c8102868d28b5ff85fc35dda07329970d1a01e273c37481326fe0c861c8142'

Randomized hashing

By setting salt parameter users can introduce randomization to the hash function. Randomized hashing is useful for protecting against collision attacks on the hash function used in digital signatures.

Randomized hashing is designed for situations where one party, the message preparer, generates all or part of a message to be signed by a second party, the message signer. If the message preparer is able to find cryptographic hash function collisions (i.e., two messages producing the same hash value), then they might prepare meaningful versions of the message that would produce the same hash value and digital signature, but with different results (e.g., transferring $1,000,000 to an account, rather than $10). Cryptographic hash functions have been designed with collision resistance as a major goal, but the current concentration on attacking cryptographic hash functions may result in a given cryptographic hash function providing less collision resistance than expected. Randomized hashing offers the signer additional protection by reducing the likelihood that a preparer can generate two or more messages that ultimately yield the same hash value during the digital signature generation process --- even if it is practical to find collisions for the hash function. However, the use of randomized hashing may reduce the amount of security provided by a digital signature when all portions of the message are prepared by the signer.

(NIST SP-800-106 "Randomized Hashing for Digital Signatures")

In BLAKE2 the salt is processed as a one-time input to the hash function during initialization, rather than as an input to each compression function.

Warning

Salted hashing (or just hashing) with BLAKE2 or any other general-purpose cryptographic hash function, such as SHA-256, is not suitable for hashing passwords. See BLAKE2 FAQ for more information.

>>> import os
>>> from hashlib import blake2b
>>> msg = b'some message'
>>> # Calculate the first hash with a random salt.
>>> salt1 = os.urandom(blake2b.SALT_SIZE)
>>> h1 = blake2b(salt=salt1)
>>> h1.update(msg)
>>> # Calculate the second hash with a different random salt.
>>> salt2 = os.urandom(blake2b.SALT_SIZE)
>>> h2 = blake2b(salt=salt2)
>>> h2.update(msg)
>>> # The digests are different.
>>> h1.digest() != h2.digest()
True

Personalization

Sometimes it is useful to force hash function to produce different digests for the same input for different purposes. Quoting the authors of the Skein hash function:

We recommend that all application designers seriously consider doing this; we have seen many protocols where a hash that is computed in one part of the protocol can be used in an entirely different part because two hash computations were done on similar or related data, and the attacker can force the application to make the hash inputs the same. Personalizing each hash function used in the protocol summarily stops this type of attack.

(The Skein Hash Function Family, p. 21)

BLAKE2 can be personalized by passing bytes to the person argument:

>>> from hashlib import blake2b
>>> FILES_HASH_PERSON = b'MyApp Files Hash'
>>> BLOCK_HASH_PERSON = b'MyApp Block Hash'
>>> h = blake2b(digest_size=32, person=FILES_HASH_PERSON)
>>> h.update(b'the same content')
>>> h.hexdigest()
'20d9cd024d4fb086aae819a1432dd2466de12947831b75c5a30cf2676095d3b4'
>>> h = blake2b(digest_size=32, person=BLOCK_HASH_PERSON)
>>> h.update(b'the same content')
>>> h.hexdigest()
'cf68fb5761b9c44e7878bfb2c4c9aea52264a80b75005e65619778de59f383a3'

Personalization together with the keyed mode can also be used to derive different keys from a single one.

>>> from hashlib import blake2s
>>> from base64 import b64decode, b64encode
>>> orig_key = b64decode(b'Rm5EPJai72qcK3RGBpW3vPNfZy5OZothY+kHY6h21KM=')
>>> enc_key = blake2s(key=orig_key, person=b'kEncrypt').digest()
>>> mac_key = blake2s(key=orig_key, person=b'kMAC').digest()
>>> print(b64encode(enc_key).decode('utf-8'))
rbPb15S/Z9t+agffno5wuhB77VbRi6F9Iv2qIxU7WHw=
>>> print(b64encode(mac_key).decode('utf-8'))
G9GtHFE1YluXY1zWPlYk1e/nWfu0WSEb0KRcjhDeP/o=

Tree mode

Here's an example of hashing a minimal tree with two leaf nodes:

  10
 /  \
00  01

This example uses 64-byte internal digests, and returns the 32-byte final digest:

>>> from hashlib import blake2b
>>>
>>> FANOUT = 2
>>> DEPTH = 2
>>> LEAF_SIZE = 4096
>>> INNER_SIZE = 64
>>>
>>> buf = bytearray(6000)
>>>
>>> # Left leaf
... h00 = blake2b(buf[0:LEAF_SIZE], fanout=FANOUT, depth=DEPTH,
...               leaf_size=LEAF_SIZE, inner_size=INNER_SIZE,
...               node_offset=0, node_depth=0, last_node=False)
>>> # Right leaf
... h01 = blake2b(buf[LEAF_SIZE:], fanout=FANOUT, depth=DEPTH,
...               leaf_size=LEAF_SIZE, inner_size=INNER_SIZE,
...               node_offset=1, node_depth=0, last_node=True)
>>> # Root node
... h10 = blake2b(digest_size=32, fanout=FANOUT, depth=DEPTH,
...               leaf_size=LEAF_SIZE, inner_size=INNER_SIZE,
...               node_offset=0, node_depth=1, last_node=True)
>>> h10.update(h00.digest())
>>> h10.update(h01.digest())
>>> h10.hexdigest()
'3ad2a9b37c6070e374c7a8c508fe20ca86b6ed54e286e93a0318e95e881db5aa'

Credits

BLAKE2 was designed by Jean-Philippe Aumasson, Samuel Neves, Zooko Wilcox-O'Hearn, and Christian Winnerlein based on SHA-3 finalist BLAKE created by Jean-Philippe Aumasson, Luca Henzen, Willi Meier, and Raphael C.-W. Phan.

It uses core algorithm from ChaCha cipher designed by Daniel J. Bernstein.

The stdlib implementation is based on pyblake2 module. It was written by Dmitry Chestnykh based on C implementation written by Samuel Neves. The documentation was copied from pyblake2 and written by Dmitry Chestnykh.

The C code was partly rewritten for Python by Christian Heimes.

The following public domain dedication applies for both C hash function implementation, extension code, and this documentation:

To the extent possible under law, the author(s) have dedicated all copyright and related and neighboring rights to this software to the public domain worldwide. This software is distributed without any warranty.

You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see https://creativecommons.org/publicdomain/zero/1.0/.

The following people have helped with development or contributed their changes to the project and the public domain according to the Creative Commons Public Domain Dedication 1.0 Universal:

• Alexandr Sokolovskiy

.. seealso::

   Module :mod:`hmac`
      A module to generate message authentication codes using hashes.

   Module :mod:`base64`
      Another way to encode binary hashes for non-binary environments.

   https://blake2.net
      Official BLAKE2 website.

   https://csrc.nist.gov/csrc/media/publications/fips/180/2/archive/2002-08-01/documents/fips180-2.pdf
      The FIPS 180-2 publication on Secure Hash Algorithms.

   https://en.wikipedia.org/wiki/Cryptographic_hash_function#Cryptographic_hash_algorithms
      Wikipedia article with information on which algorithms have known issues and
      what that means regarding their use.

   https://www.ietf.org/rfc/rfc8018.txt
      PKCS #5: Password-Based Cryptography Specification Version 2.1

   https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf
      NIST Recommendation for Password-Based Key Derivation.