OVMS3/OVMS.V3/components/wolfssl/wrapper/python/wolfcrypt/docs/mac.rst

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Message Authentication Codes
============================
.. module:: wolfcrypt.hashes
A **message authentication code** (MAC) is a short piece of information used
to authenticate a message — in other words, to confirm that the message came
from the stated sender (its authenticity) and has not been changed in transit
(its integrity).
``wolfcrypt`` implements the **Hash-based message authentication code** (HMAC),
which uses a cryptographic hash function coupled with a secret key to produce
**message authentication codes**.
Hmac Classes
------------
Interface
~~~~~~~~~
All Hmac classes available in this module implements the following
interface:
.. autoclass:: _Hmac
:members:
:inherited-members:
SHA-1
~~~~~
.. attention::
NIST has deprecated SHA-1 in favor of the SHA-2 variants. New applications
are strongly suggested to use SHA-2 over SHA-1.
.. autoclass:: HmacSha
SHA-2 family
~~~~~~~~~~~~
.. autoclass:: HmacSha256
.. autoclass:: HmacSha384
.. autoclass:: HmacSha512
Example
-------
.. doctest::
>>> from wolfcrypt.hashes import HmacSha256
>>>
>>> h = HmacSha256('secret')
>>> h.update("wolf")
>>> h.update("crypt")
>>> h.digest()
b'\x18\xbf*\t9\xa2o\xdf\\\xc8\xe0\xc2U\x94,\x8dY\x02;\x1c<Q\xdf\x8d\xdb\x863\xfb\xc1f#o'
>>> h.hexdigest()
b'18bf2a0939a26fdf5cc8e0c255942c8d59023b1c3c51df8ddb8633fbc166236f'
>>>
>>> h.update("rocks")
>>> h.hexdigest()
b'85dc8c1995d20b17942d52773d8a597d028ad958e5736beafb59a4742f63889e'
>>>
>>> HmacSha256('secret', 'wolfcryptrocks').hexdigest()
b'85dc8c1995d20b17942d52773d8a597d028ad958e5736beafb59a4742f63889e'
>>>
>>> HmacSha256.new('secret', 'wolfcryptrocks').hexdigest()
b'85dc8c1995d20b17942d52773d8a597d028ad958e5736beafb59a4742f63889e'