ref: 34f5a8333090c5090e1d0b6ddbaf900d64340eea
dir: /sys/src/cmd/python/Doc/lib/libhmac.tex/
\section{\module{hmac} ---
Keyed-Hashing for Message Authentication}
\declaremodule{standard}{hmac}
\modulesynopsis{Keyed-Hashing for Message Authentication (HMAC)
implementation for Python.}
\moduleauthor{Gerhard H{\"a}ring}{[email protected]}
\sectionauthor{Gerhard H{\"a}ring}{[email protected]}
\versionadded{2.2}
This module implements the HMAC algorithm as described by \rfc{2104}.
\begin{funcdesc}{new}{key\optional{, msg\optional{, digestmod}}}
Return a new hmac object. If \var{msg} is present, the method call
\code{update(\var{msg})} is made. \var{digestmod} is the digest
constructor or module for the HMAC object to use. It defaults to
the \code{\refmodule{hashlib}.md5} constructor. \note{The md5 hash
has known weaknesses but remains the default for backwards compatibility.
Choose a better one for your application.}
\end{funcdesc}
An HMAC object has the following methods:
\begin{methoddesc}[hmac]{update}{msg}
Update the hmac object with the string \var{msg}. Repeated calls
are equivalent to a single call with the concatenation of all the
arguments: \code{m.update(a); m.update(b)} is equivalent to
\code{m.update(a + b)}.
\end{methoddesc}
\begin{methoddesc}[hmac]{digest}{}
Return the digest of the strings passed to the \method{update()}
method so far. This string will be the same length as the
\var{digest_size} of the digest given to the constructor. It
may contain non-\ASCII{} characters, including NUL bytes.
\end{methoddesc}
\begin{methoddesc}[hmac]{hexdigest}{}
Like \method{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.
\end{methoddesc}
\begin{methoddesc}[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.
\end{methoddesc}
\begin{seealso}
\seemodule{hashlib}{The python module providing secure hash functions.}
\end{seealso}