.\"	$OpenBSD: md5.1,v 1.43 2014/03/07 04:10:55 lteo Exp $
.\"
.\" Copyright (c) 2003, 2004, 2006 Todd C. Miller <Todd.Miller@courtesan.com>
.\"
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.\" copyright notice and this permission notice appear in all copies.
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.\" Sponsored in part by the Defense Advanced Research Projects
.\" Agency (DARPA) and Air Force Research Laboratory, Air Force
.\" Materiel Command, USAF, under agreement number F39502-99-1-0512.
.\"
.Dd $Mdocdate: March 7 2014 $
.Dt MD5 1
.Os
.Sh NAME
.Nm md5
.Nd calculate a message digest (checksum) for a file
.Sh SYNOPSIS
.Nm md5
.Op Fl bcpqrtx
.Op Fl C Ar checklist
.Op Fl h Ar hashfile
.Op Fl s Ar string
.Op Ar
.Nm sha1
.Op Fl bcpqrtx
.Op Fl C Ar checklist
.Op Fl h Ar hashfile
.Op Fl s Ar string
.Op Ar
.Nm sha256
.Op Fl bcpqrtx
.Op Fl C Ar checklist
.Op Fl h Ar hashfile
.Op Fl s Ar string
.Op Ar
.Nm sha512
.Op Fl bcpqrtx
.Op Fl C Ar checklist
.Op Fl h Ar hashfile
.Op Fl s Ar string
.Op Ar
.Sh DESCRIPTION
These utilities take as input a message of arbitrary length and produce
as output a message digest (checksum) of the input.
It is conjectured that it is computationally infeasible to produce
two messages having the same message digest (a collision),
or to produce any message having a given prespecified target message digest.
The algorithm (MD5, SHA-1, SHA-256, SHA-512) is determined by the
name used to invoke the utility.
.Pp
Collisions have now been produced for MD5, and are theorized for SHA-1,
so their use is deprecated.
.Pp
The options for use with each command are as follows:
.Bl -tag -width Ds
.It Fl b
Output checksums in base64 notation, not hexadecimal.
.It Fl C Ar checklist
Compare the checksum of each
.Ar file
against the checksums in the
.Ar checklist .
Any specified
.Ar file
that is not listed in the
.Ar checklist
will generate an error.
.It Fl c
If this option is specified, the
.Ar file
options become checklists.
Each checklist should contain hash results in the normal format,
which will be verified against the specified paths.
Output consists of the digest used, the file name,
and an OK, FAILED, or MISSING for the result of the comparison.
This will validate any of the supported checksums (see
.Xr cksum 1 ) .
If no file is given, stdin is used.
.It Fl h Ar hashfile
Place the checksum into
.Ar hashfile
instead of stdout.
.It Fl p
Echoes stdin to stdout and appends the
checksum to stdout.
.It Fl q
Only print the checksum (quiet mode).
.It Fl r
Reverse the format of the hash algorithm output, making
it match the output format used by
.Xr cksum 1 .
.It Fl s Ar string
Prints a checksum of the given
.Ar string .
.It Fl t
Runs a built-in time trial.
Specifying
.Fl t
multiple times results in the number of rounds being multiplied
by 10 for each additional flag.
.It Fl x
Runs a built-in test script.
.El
.Sh EXIT STATUS
These utilities exit 0 on success,
and \*(Gt0 if an error occurs.
.Sh SEE ALSO
.Xr cksum 1
.Sh STANDARDS
.Rs
.%A R. Rivest
.%D April 1992
.%R RFC 1321
.%T The MD5 Message-Digest Algorithm
.Re
.Rs
.%A J. Burrows
.%O FIPS PUB 180-1
.%T The Secure Hash Standard
.Re
.Pp
.Rs
.%A D. Eastlake
.%A P. Jones
.%D September 2001
.%R RFC 3174
.%T US Secure Hash Algorithm 1 (SHA1)
.Re
.Rs
.%T Secure Hash Standard
.%O FIPS PUB 180-2
.Re
.Sh CAVEATS
Since collisions have been found for MD5,
the use of
.Nm sha256
is recommended instead.