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Diffstat (limited to 'Doc/lib/libmd5.tex')
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1 files changed, 30 insertions, 27 deletions
diff --git a/Doc/lib/libmd5.tex b/Doc/lib/libmd5.tex index 0dfa65e..bd26f02 100644 --- a/Doc/lib/libmd5.tex +++ b/Doc/lib/libmd5.tex @@ -1,61 +1,64 @@ -\section{Built-in module \sectcode{md5}} +\section{Built-in Module \sectcode{md5}} \bimodindex{md5} This module implements the interface to RSA's MD5 message digest -algorithm (see also the file \file{md5.doc}). Its use is quite -straightforward:\ use the function \code{new} to create an -\dfn{md5}-object. You can now ``feed'' this object with arbitrary -strings. - -At any time you can ask for the ``final'' digest of the object. Internally, -a temporary copy of the object is made and the digest is computed and -returned. Because of the copy, the digest operation is not destructive -for the object. Before a more exact description of the module's use, a small -example will be helpful: -to obtain the digest of the string \code{'abc'}, use \ldots +algorithm (see also Internet RFC 1321). Its use is quite +straightforward:\ use the \code{md5.new()} to create an md5 object. +You can now feed this object with arbitrary strings using the +\code{update()} method, and at any point you can ask it for the +\dfn{digest} (a strong kind of 128-bit checksum, +a.k.a. ``fingerprint'') of the contatenation of the strings fed to it +so far using the \code{digest()} method. + +For example, to obtain the digest of the string {\tt"Nobody inspects +the spammish repetition"}: \bcode\begin{verbatim} >>> import md5 >>> m = md5.new() ->>> m.update('abc') +>>> m.update("Nobody inspects") +>>> m.update(" the spammish repetition") >>> m.digest() -'\220\001P\230<\322O\260\326\226?}(\341\177r' +'\273d\234\203\335\036\245\311\331\336\311\241\215\360\377\351' \end{verbatim}\ecode More condensed: \bcode\begin{verbatim} ->>> md5.new('abc').digest() -'\220\001P\230<\322O\260\326\226?}(\341\177r' +>>> md5.new("Nobody inspects the spammish repetition").digest() +'\273d\234\203\335\036\245\311\331\336\311\241\215\360\377\351' \end{verbatim}\ecode \renewcommand{\indexsubitem}{(in module md5)} \begin{funcdesc}{new}{\optional{arg}} - Create a new md5-object. If \var{arg} is present, an initial - \code{update} method is called with \var{arg} as argument. +Return a new md5 object. If \var{arg} is present, the method call +\code{update(\var{arg})} is made. \end{funcdesc} \begin{funcdesc}{md5}{\optional{arg}} For backward compatibility reasons, this is an alternative name for the -\code{new} function. +\code{new()} function. \end{funcdesc} -An md5-object has the following methods: +An md5 object has the following methods: \renewcommand{\indexsubitem}{(md5 method)} \begin{funcdesc}{update}{arg} - Update this md5-object with the string \var{arg}. +Update the md5 object with the string \var{arg}. Repeated calls are +equivalent to a single call with the concatenation of all the +arguments, i.e.\ \code{m.update(a); m.update(b)} is equivalent to +\code{m.update(a+b)}. \end{funcdesc} \begin{funcdesc}{digest}{} -% XXX The following is not quite clear; what does MD5Final do? - Return the \dfn{digest} of this md5-object. Internally, a copy is made - and the \C-function \code{MD5Final} is called. Finally the digest is - returned. +Return the digest of the strings passed to the \code{update()} +method so far. This is an 8-byte string which may contain +non-\ASCII{} characters, including null bytes. \end{funcdesc} \begin{funcdesc}{copy}{} - Return a separate copy of this md5-object. An \code{update} to this - copy won't affect the original object. +Return a copy (``clone'') of the md5 object. This can be used to +efficiently compute the digests of strings that share a common initial +substring. \end{funcdesc} |