mirror of
https://github.com/python/cpython.git
synced 2025-11-04 07:31:38 +00:00
57 lines
1.9 KiB
TeX
57 lines
1.9 KiB
TeX
|
\section{\module{sha} ---
|
||
|
|
SHA message digest algorithm}
|
||
|
|
|
||
|
|
\declaremodule{builtin}{sha}
|
||
|
|
\modulesynopsis{NIST's secure hash algorithm, SHA.}
|
||
|
|
\sectionauthor{Fred L. Drake, Jr.}{fdrake@acm.org}
|
||
|
|
|
||
|
|
|
||
|
|
This module implements the interface to NIST's\index{NIST} secure hash
|
||
|
|
algorithm,\index{Secure Hash Algorithm} known as SHA. It is used in
|
||
|
|
the same way as the \refmodule{md5} module:\ use the \function{new()}
|
||
|
|
to create an sha object, then feed this object with arbitrary strings
|
||
|
|
using the \method{update()} method, and at any point you can ask it
|
||
|
|
for the \dfn{digest} of the contatenation of the strings fed to it
|
||
|
|
so far.\index{checksum!SHA} SHA digests are 160 bits instead of 128
|
||
|
|
bits.
|
||
|
|
|
||
|
|
|
||
|
|
\begin{funcdesc}{new}{\optional{string}}
|
||
|
|
Return a new sha object. If \var{string} is present, the method
|
||
|
|
call \code{update(\var{string})} is made.
|
||
|
|
\end{funcdesc}
|
||
|
|
|
||
|
|
|
||
|
|
The following values are provided as constants in the module and as
|
||
|
|
attributes of the sha objects returned by \function{new()}:
|
||
|
|
|
||
|
|
\begin{datadesc}{blocksize}
|
||
|
|
Size of the blocks fed into the hash function; this is always
|
||
|
|
\code{1}. This size is used to allow an arbitrary string to be
|
||
|
|
hashed.
|
||
|
|
\end{datadesc}
|
||
|
|
|
||
|
|
\begin{datadesc}{digestsize}
|
||
|
|
The size of the resulting digest in bytes. This is always
|
||
|
|
\code{20}.
|
||
|
|
\end{datadesc}
|
||
|
|
|
||
|
|
|
||
|
|
A sha object has all the methods the md5 objects have, plus one:
|
||
|
|
|
||
|
|
\begin{methoddesc}[sha]{hexdigest}{}
|
||
|
|
Return the digest value as a string of hexadecimal digits. This may
|
||
|
|
be used to exchange the value safely in email or other non-binary
|
||
|
|
environments.
|
||
|
|
\end{methoddesc}
|
||
|
|
|
||
|
|
|
||
|
|
\begin{seealso}
|
||
|
|
\seetext{The Secure Hash Algorithm is defined by NIST document FIPS
|
||
|
|
PUB 180-1: \emph{Secure Hash Standard}, published in April
|
||
|
|
of 1995. It is available online as plain text at
|
||
|
|
\url{http://csrc.nist.gov/fips/fip180-1.txt} (at least one
|
||
|
|
diagram was omitted) and as PostScript at
|
||
|
|
\url{http://csrc.nist.gov/fips/fip180-1.ps}.}
|
||
|
|
\end{seealso}
|