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XSUM User's Manual XSUM


NNAAMMEE
crc, mdx - generate checksums of a file or files

SSYYNNOOPPSSIISS
ccrrcc [_o_p_t_i_o_n_s | _f_i_l_e_s_p_e_c] _._._.
mmddxx [_o_p_t_i_o_n_s | _f_i_l_e_s_p_e_c] _._._.

VVEERRSSIIOONN
_c_r_c version 11..0077
_m_d_x version 11..0055

DDEESSCCRRIIPPTTIIOONN
_c_r_c and _m_d_x compute the checksum of a file or a set of files.
_c_r_c computes the 32-bit Cyclical Redundancy Check (CCRRCC--3322) and
_m_d_x computes the 128-bit Message Digest (MMDD44 or MMDD55).
Running either one with no parameters will give a quick
summary of function and options.

OOUUTTPPUUTT
The output of both programs is written to standard output
(ssttddoouutt), and can be redirected to a file. The title and
any error messages will be sent to standard error (ssttddeerrrr).

The basic output of _c_r_c is formatted as:

e0c8a642 filename

and the basic output of _m_d_x is formatted as:

e0c8a642e0c8a642e0c8a642e0c8a642 MD_x filename

where _x is replaced by 5 or 4 to indicate MMDD55 or MMDD44.

In addition, each program has an extended output mode where extra
information is given about each file processed. This information
includes the file size, the file time (with seconds) and the file
date (with century).

The extended output of _c_r_c is formatted as:

e0c8a642 1,234,567,890 23:36:18 01-Jan-1980 filename

and the extended output of _m_d_x is formatted as:

e0c8a642e0c8a642e0c8a642e0c8a642 MD_x filename
1,457,664 08:45:58 05-Feb-1995



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XSUM User's Manual XSUM


Be advised that a file which has its seconds set to 62 or its
year set ahead a century (e.g., 2095 instead of 1995) may be
infected with a virus. This is not necessarily the case, but
there are some viruses which mark infected files in this way.

OOPPTTIIOONNSS
_f_i_l_e_s_p_e_c The name of a file or a pattern which matches
several files. The drive and path may be
specified, and there is no limit to the number
of files matched. Also, as many filenames or
patterns as will fit on the command line may
be given.

The following options apply only to _m_d_x:

_-_4 Use the MD4 algorithm.

_-_5 Use the MD5 algorithm (default).

_-_n Don't use the faster 386 code.

_-_n_n Don't check for the presence of a 386 processor.

The _-_4 and _-_5 options may be used more than once on the command
line. Whichever was last given affects which algorithm is used,
so MMDD44 and MMDD55 message digests can be computed on the same run.
For example,

mmddxx --44 **..eexxee **..ccoomm **..ssyyss --55 **..ttxxtt **..ddoocc **..mmaann

would calculate the MMDD44 digests of all the programs in the
current directory, and the MMDD55 digests of all the text. Or,


mmddxx ffoooo..bbaarr --44 ffoooo..bbaarr

would calculate both numbers for the file ffoooo..bbaarr.

The _-_n and _-_n_n options allow you to run the standard MD5 code
instead of the faster 386-specific code. The only reason you
would want to do this is to make a speed comparison. Normally
_m_d_x uses an enhanced 32-bit version of the MMDD55 _t_r_a_n_s_l_a_t_e
function, if it detects a 386 or better processor. Just in case
this causes a problem (which it shouldn't), you can force _m_d_x to
use the slower (but compatible) code with the _-_n switch, or even
suppress the test for the 386 entirely with the _-_n_n switch.




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XSUM User's Manual XSUM


The following options apply to both _m_d_x and _c_r_c:

_-_h show the help screen.

_-_e display extended file information.

The _-_h switch shows the same usage summary that is given if
the programs are run with no parameters.


The _-_e switch selects the extended output format which
includes the file size, time, and date.

EERRRROORRSS
All errors are of the form pprrgg:: mmeessssaaggee where pprrgg is either
_c_r_c or _m_d_x.

pprrgg: error opening file nnaammee

The file nnaammee could not be opened for reading. It
may be locked by another application.

pprrgg: error reading file nnaammee

An error occurred while reading file nnaammee. The
disk may be damaged.

pprrgg: no files found to process

None of the _f_i_l_e_s_p_e_cs given on the command line
matched any files.

pprrgg: program has been modified

On startup, the program checks itself to see if it
has been modified. This provides some protection
against viruses however it will not detect stealth
viruses.

If the self-check fails, the program displays this
message and exits.

pprrgg: integrity cannot be verified

If the self-check cannot be performed then this message
is displayed, and the program continues. This could
happen if the self-checking information is tampered
with, or if the program is run under DOS 2.x.


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XSUM User's Manual XSUM



Note that the self check code is smart enough not to be bothered
by the addition of validation data, which certain anti-virus
programs foolishly append to the executable file, nor is it
bothered if the compressed executables are expanded.

AAUUTTHHOORR
crc and mdx were written by David R. Conrad, who can be reached
in the following ways, in order of preference:

Internet [email protected]
Mail 432 Alter Rd.
Detroit, MI 48215-3105 USA

Users who have sent email to [email protected] will
please note that that address is (temporarily) disabled, and
any mail sent to it may not be read in a timely manner, if at
all. Please use the Greater Detroit FreeNet address instead.

AACCKKNNOOWWLLEEDDGGEEMMEENNTTSS
These programs would not exist without the code of Gary S. Brown
which I obtained by way of Rahul Dhesi, and of course the work
of Ron Rivest, both in developing MMDD44 and MMDD55 and in writing
the reference implementations thereof. I would also like to
thank Phil Karn. Without his mmdd55ttrraannss code _m_d_x would run much
slower. The 386 detection is based on the pp8877tteesstt program by
Terje Mathisen. My special thanks to Vesselin Bontchev who made
several excellent suggestions which have helped with the
development of _m_d_x.

LLEEGGAALLIITTIIEESS
_c_r_c and _m_d_x are Copyright 1993-1995 David R. Conrad.
All rights reserved.

The CCRRCC--3322 implementation used was extracted from the source
of bbrriikk by Rahul Dhesi, and is from the zzmmooddeemm source code,
and is Copyright 1986 Gary S. Brown. Used with permission.

MMDD44 is the RSA Data Security, Inc. MD4 Message-Digest Algorithm,
Copyright 1990 RSA Data Security, Inc. Used with permission.

MMDD55 is the RSA Data Security, Inc. MD5 Message-Digest Algorithm,
Copyright 1991 RSA Data Security, Inc. Used with permission.

MMDD55ttrraannss is a public domain implementation of the MD5 translate
function written by Phil Karn. Used with permission.



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XSUM User's Manual XSUM


David R. Conrad hereby disclaims all warranties relating to
this software, whether express or implied, including without
limitation any implied warranties of merchantability or fitness
for a particular purpose. I will not be liable for any special,
incidental, consequential, indirect or similar damages due to
loss of data or any other reason. In no case can Rahul Dhesi,
Gary S. Brown, Phil Karn, or RSA Data Security, Inc. be held
liable in any way for damages resulting from the use of this
software or otherwise related to this software.

_c_r_c and _m_d_x are freeware, meaning that they are copyrighted
but can be used and distributed free of charge, as long as they
are distributed in an unmodified form.




































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