--- /dev/null
+%%
+%%
+
+\chapter{Bacula MD5 Algorithm}
+\label{MD5Chapter}
+\addcontentsline{toc}{section}{}
+
+\section{Command Line Message Digest Utility }
+\index{Utility!Command Line Message Digest }
+\index{Command Line Message Digest Utility }
+\addcontentsline{toc}{subsection}{Command Line Message Digest Utility}
+
+
+This page describes {\bf md5}, a command line utility usable on either Unix or
+MS-DOS/Windows, which generates and verifies message digests (digital
+signatures) using the MD5 algorithm. This program can be useful when
+developing shell scripts or Perl programs for software installation, file
+comparison, and detection of file corruption and tampering.
+
+\subsection{Name}
+\index{Name}
+\addcontentsline{toc}{subsubsection}{Name}
+
+{\bf md5} - generate / check MD5 message digest
+
+\subsection{Synopsis}
+\index{Synopsis }
+\addcontentsline{toc}{subsubsection}{Synopsis}
+
+{\bf md5} [ {\bf -c}{\it signature} ] [ {\bf -u} ] [ {\bf -d}{\it input\_text}
+| {\it infile} ] [ {\it outfile} ]
+
+\subsection{Description}
+\index{Description }
+\addcontentsline{toc}{subsubsection}{Description}
+
+A {\it message digest} is a compact digital signature for an arbitrarily long
+stream of binary data. An ideal message digest algorithm would never generate
+the same signature for two different sets of input, but achieving such
+theoretical perfection would require a message digest as long as the input
+file. Practical message digest algorithms compromise in favour of a digital
+signature of modest size created with an algorithm designed to make
+preparation of input text with a given signature computationally infeasible.
+Message digest algorithms have much in common with techniques used in
+encryption, but to a different end; verification that data have not been
+altered since the signature was published.
+
+Many older programs requiring digital signatures employed 16 or 32 bit {\it
+cyclical redundancy codes} (CRC) originally developed to verify correct
+transmission in data communication protocols, but these short codes, while
+adequate to detect the kind of transmission errors for which they were
+intended, are insufficiently secure for applications such as electronic
+commerce and verification of security related software distributions.
+
+The most commonly used present-day message digest algorithm is the 128 bit MD5
+algorithm, developed by Ron Rivest of the
+\elink{MIT}{http://web.mit.edu/}
+\elink{Laboratory for Computer Science}{http://www.lcs.mit.edu/} and
+\elink{RSA Data Security, Inc.}{http://www.rsa.com/} The algorithm, with a
+reference implementation, was published as Internet
+\elink{RFC 1321}{http://www.fourmilab.ch/md5/rfc1321.html} in April 1992, and
+was placed into the public domain at that time. Message digest algorithms such
+as MD5 are not deemed ``encryption technology'' and are not subject to the
+export controls some governments impose on other data security products.
+(Obviously, the responsibility for obeying the laws in the jurisdiction in
+which you reside is entirely your own, but many common Web and Mail utilities
+use MD5, and I am unaware of any restrictions on their distribution and use.)
+
+The MD5 algorithm has been implemented in numerous computer languages
+including C,
+\elink{Perl}{http://www.perl.org/}, and
+\elink{Java}{http://www.javasoft.com/}; if you're writing a program in such a
+language, track down a suitable subroutine and incorporate it into your
+program. The program described on this page is a {\it command line}
+implementation of MD5, intended for use in shell scripts and Perl programs (it
+is much faster than computing an MD5 signature directly in Perl). This {\bf
+md5} program was originally developed as part of a suite of tools intended to
+monitor large collections of files (for example, the contents of a Web site)
+to detect corruption of files and inadvertent (or perhaps malicious) changes.
+That task is now best accomplished with more comprehensive packages such as
+\elink{Tripwire}{ftp://coast.cs.purdue.edu/pub/COAST/Tripwire/}, but the
+command line {\bf md5} component continues to prove useful for verifying
+correct delivery and installation of software packages, comparing the contents
+of two different systems, and checking for changes in specific files.
+
+\subsection{Options}
+\index{Options }
+\addcontentsline{toc}{subsubsection}{Options}
+
+\begin{description}
+
+\item [{\bf -c}{\it signature} ]
+ \index{-csignature }
+ Computes the signature of the specified {\it infile} or the string supplied
+by the {\bf -d} option and compares it against the specified {\it signature}.
+If the two signatures match, the exit status will be zero, otherwise the exit
+status will be 1. No signature is written to {\it outfile} or standard
+output; only the exit status is set. The signature to be checked must be
+specified as 32 hexadecimal digits.
+
+\item [{\bf -d}{\it input\_text} ]
+ \index{-dinput\_text }
+ A signature is computed for the given {\it input\_text} (which must be quoted
+if it contains white space characters) instead of input from {\it infile} or
+standard input. If input is specified with the {\bf -d} option, no {\it
+infile} should be specified.
+
+\item [{\bf -u} ]
+ Print how-to-call information.
+ \end{description}
+
+\subsection{Files}
+\index{Files }
+\addcontentsline{toc}{subsubsection}{Files}
+
+If no {\it infile} or {\bf -d} option is specified or {\it infile} is a single
+``-'', {\bf md5} reads from standard input; if no {\it outfile} is given, or
+{\it outfile} is a single ``-'', output is sent to standard output. Input and
+output are processed strictly serially; consequently {\bf md5} may be used in
+pipelines.
+
+\subsection{Bugs}
+\index{Bugs }
+\addcontentsline{toc}{subsubsection}{Bugs}
+
+The mechanism used to set standard input to binary mode may be specific to
+Microsoft C; if you rebuild the DOS/Windows version of the program from source
+using another compiler, be sure to verify binary files work properly when read
+via redirection or a pipe.
+
+This program has not been tested on a machine on which {\tt int} and/or {\tt
+long} are longer than 32 bits.
+
+\section{
+\elink{Download md5.zip}{http://www.fourmilab.ch/md5/md5.zip} (Zipped
+archive)}
+\index{Archive!Download md5.zip Zipped }
+\index{Download md5.zip (Zipped archive) }
+\addcontentsline{toc}{subsection}{Download md5.zip (Zipped archive)}
+
+The program is provided as
+\elink{md5.zip}{http://www.fourmilab.ch/md5/md5.zip}, a
+\elink{Zipped}{http://www.pkware.com/} archive containing an ready-to-run
+Win32 command-line executable program, {\tt md5.exe} (compiled using Microsoft
+Visual C++ 5.0), and in source code form along with a {\tt Makefile} to build
+the program under Unix.
+
+\subsection{See Also}
+\index{ALSO!SEE }
+\index{See Also }
+\addcontentsline{toc}{subsubsection}{SEE ALSO}
+
+{\bf sum}(1)
+
+\subsection{Exit Status}
+\index{Status!Exit }
+\index{Exit Status }
+\addcontentsline{toc}{subsubsection}{Exit Status}
+
+{\bf md5} returns status 0 if processing was completed without errors, 1 if
+the {\bf -c} option was specified and the given signature does not match that
+of the input, and 2 if processing could not be performed at all due, for
+example, to a nonexistent input file.
+
+\subsection{Copying}
+\index{Copying }
+\addcontentsline{toc}{subsubsection}{Copying}
+
+\begin{quote}
+This software is in the public domain. Permission to use, copy, modify, and
+distribute this software and its documentation for any purpose and without
+fee is hereby granted, without any conditions or restrictions. This software
+is provided ``as is'' without express or implied warranty.
+\end{quote}
+
+\subsection{Acknowledgements}
+\index{Acknowledgements }
+\addcontentsline{toc}{subsubsection}{Acknowledgements}
+
+The MD5 algorithm was developed by Ron Rivest. The public domain C language
+implementation used in this program was written by Colin Plumb in 1993.
+{\it
+\elink{by John Walker}{http://www.fourmilab.ch/}
+January 6th, MIM }
projects / bacula / docs / blobdiff