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+:mod:`hmac` --- Keyed-Hashing for Message Authentication
+========================================================
+
+.. module:: hmac
+ :synopsis: Keyed-Hashing for Message Authentication (HMAC) implementation for Python.
+.. moduleauthor:: Gerhard Häring <ghaering@users.sourceforge.net>
+.. sectionauthor:: Gerhard Häring <ghaering@users.sourceforge.net>
+
+
+.. versionadded:: 2.2
+
+This module implements the HMAC algorithm as described by :rfc:`2104`.
+
+
+.. function:: new(key[, msg[, digestmod]])
+
+ Return a new hmac object. If *msg* is present, the method call ``update(msg)``
+ is made. *digestmod* is the digest constructor or module for the HMAC object to
+ use. It defaults to the :func:`hashlib.md5` constructor.
+
+ .. note::
+
+ The md5 hash has known weaknesses but remains the default for backwards
+ compatibility. Choose a better one for your application.
+
+An HMAC object has the following methods:
+
+
+.. method:: hmac.update(msg)
+
+ Update the hmac object with the string *msg*. 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)``.
+
+
+.. method:: hmac.digest()
+
+ Return the digest of the strings passed to the :meth:`update` method so far.
+ This string will be the same length as the *digest_size* of the digest given to
+ the constructor. It may contain non-ASCII characters, including NUL bytes.
+
+
+.. method:: hmac.hexdigest()
+
+ Like :meth:`digest` except the digest is returned as a string twice the length
+ containing only hexadecimal digits. This may be used to exchange the value
+ safely in email or other non-binary environments.
+
+
+.. method:: hmac.copy()
+
+ Return a copy ("clone") of the hmac object. This can be used to efficiently
+ compute the digests of strings that share a common initial substring.
+
+
+.. seealso::
+
+ Module :mod:`hashlib`
+ The python module providing secure hash functions.
+