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58 lines
1.9 KiB
ReStructuredText
58 lines
1.9 KiB
ReStructuredText
:mod:`hmac` --- Keyed-Hashing for Message Authentication
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========================================================
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.. module:: hmac
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:synopsis: Keyed-Hashing for Message Authentication (HMAC) implementation for Python.
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.. moduleauthor:: Gerhard Häring <ghaering@users.sourceforge.net>
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.. sectionauthor:: Gerhard Häring <ghaering@users.sourceforge.net>
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This module implements the HMAC algorithm as described by :rfc:`2104`.
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.. function:: new(key, msg=None, digestmod=None)
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Return a new hmac object. If *msg* is present, the method call ``update(msg)``
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is made. *digestmod* is the digest constructor or module for the HMAC object to
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use. It defaults to the :func:`hashlib.md5` constructor.
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.. note::
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The md5 hash has known weaknesses but remains the default for backwards
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compatibility. Choose a better one for your application.
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An HMAC object has the following methods:
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.. method:: hmac.update(msg)
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Update the hmac object with the string *msg*. Repeated calls are equivalent to
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a single call with the concatenation of all the arguments: ``m.update(a);
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m.update(b)`` is equivalent to ``m.update(a + b)``.
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.. method:: hmac.digest()
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Return the digest of the strings passed to the :meth:`update` method so far.
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This string will be the same length as the *digest_size* of the digest given to
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the constructor. It may contain non-ASCII characters, including NUL bytes.
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.. method:: hmac.hexdigest()
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Like :meth:`digest` except the digest is returned as a string twice the length
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containing only hexadecimal digits. This may be used to exchange the value
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safely in email or other non-binary environments.
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.. method:: hmac.copy()
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Return a copy ("clone") of the hmac object. This can be used to efficiently
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compute the digests of strings that share a common initial substring.
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.. seealso::
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Module :mod:`hashlib`
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The python module providing secure hash functions.
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