NAME
          md5 - RSA Data Security, Inc. MD5 Message-Digest Algorithm

     SYNOPSIS
          md5 [ -cdhiqtx ][ -pprefix ][ -Pprfile ][ -sstr ] file ...

     DESCRIPTION
          The md5 utility implements the RSA Data Security, Inc. MD5
          Message-Digest Algorithm (MD5).  It produces 128-bit MD5
          Digests of files, strings or data read on stdin.  If no file
          is given, and no string is to be digested (-s) then stdin
          will be digested.  By default, a digests are printed as 40
          hex characters without a leading 0x.

          The algorithm takes as input an input message of arbitrary
          length and produces as output a 128-bit ``fingerprint'' or
          ``message digest'' of the input. It is conjectured that it
          is computationally infeasible to produce two messages having
          the same message digest, or to produce any message having a
          given prespecified target message digest. The MD5 algorithm
          is intended for digital signature applications, where a
          large file must be ``compressed'' in a secure manner before
          being encrypted with a private (secret) key under a public-
          key cryptosystem such as RSA.

          If a str (string) argument is given, then the digest for
          str, followed by a space, followed by str enclosed double
          quotes is written to stdout.  Any file arguments are
          ignored.

          If one or more file if given, a separate digest if produced
          for each file.  By default, file digests are followed by a
          space and the filename.

          If no str or file arguments are given, then a digest of
          stdin is written to stdout.

          -c   Print C style hex digests with a leading 0x.

          -d   Compute dual digests.

               Data is divided into two streams and digested
               separately.  Each successive octet is assigned an index
               starting with 0.  The even stream consists of octets
               with even indices.  The odd stream consists of octets
               with odd indices.  The even stream digest, followed by
               a space, followed by the odd stream digest is written
               to stdout.

          -h   Print a help and usage message.

          -i   Compute inode digests of files.
               Prepend the filename and various inode information to
               the file data being digested.  The inode information
               prepended includes information such as the device
               (st_dev), inode number (st_ino), mode (st_mode), link
               count (st_nlink), uid (st_uid), gid (st_gid), size
               (st_size), modification time (st_mtime) and change time
               (st_ctime).  The prepended data is padded with zeros to
               make it a multiple of 64 bytes long.  Both a stat(2)
               and a lstat(2) information are both used.

               The -i flag allows one to include various inode
               information in the digest. This option is useful in
               detecting file tampering.  For example, the following
               will produce different digests:

                    md5 -i /tmp/chongo
                    cp /tmp/chongo /tmp/was_here
                    cp /tmp/was_here /tmp/chongo
                    md5 -i /tmp/chongo

               Note that a -i digest is portable to other systems.
               This is because inode information will likely change as
               the contents of a file are copied from machine to
               machine.

               To mark a -i digest as a special value, .0 is prepended
               onto the digest output.

               One may only compute inode digests of files.  Use of -i
               disables reading from stdin.  The -i flag is not
               compatible with -s.

          -pprefix

          -Pprfile
               Insert a prefix into the data to be digested.

               By using -pprefix, one may prepend any set of data with
               a string. The digest produced is equivalent to digest
               that is produced with the string pretended to the data.
               Thus the following two commands produce the same
               digest:

                    md5 -p curds -s whey
                    md5 -s curdswhey

               By use of the -Pprfile interface, one may prepend using
               up to the 32k of a file. This interface allows one to
               prepend using binary data. The following produces the
               same digest:

                    md5 -P /usr/bin/awk /bin/ls
                    dd if=/usr/bin/awk of=/tmp/foo bs=32k count=1
                    cat /tmp/foo /bin/ls > /tmp/ls
                    md5 /tmp/ls

               Knowledge of the original prepend data is only kept in
               the digest. Thus one may use the prepend string as a
               ``salt'' making it intractable for someone else to
               reproduce the digest of a file without knowledge of the
               prepend data.

               For sightly faster performance, use prepend data that
               is a multiple of 64 bytes long. The easy way to do this
               is to use -P on a file that is at least 32k bytes in
               length.

               This feature works in conjunction all modes of
               operation except the -t and -x modes.

          -q   Output only digests.  The filename or string will not
               be written to stdout.

          -sstr
               Digest str as if it were a string.

               The trailing NUL byte is not digested.  No files are
               digested.  The str is written to stdout enclosed in
               double quotes.

          -t   Time the user cpu seconds needed to digest several
               megabytes of data.  The number of megabytes, followed
               by the digest produced, followed by the number of user
               cpu seconds followed by the number of characters per
               user second is written to stdout.

               On some systems with certain virtual memory
               characteristics, you may need to run the performance
               test several times, ignoring the first result.  The
               default amount of data tested is 16 megabytes.  On some
               systems, this amount may differ.  One may change the
               number of megabytes processed by changing the value of
               TEST_MEG in the file md5drvr.c and recompiling.

          -v   Print the version.

          -x   Perform an extended standard SHS test suite.

               The test suite will first look in the current directory
               for file1.  If it is not found, it will look in
               ${DESTDIR} (usually /usr/local/lib/md5).  It is assumes
               that file2 is in the same location as

               The standard test suite been extended. The initial
               string now says:

                    md5 test suite results

               instead of:

                    SHA test suite results

               to reflect the utility name instead of the algorithm
               implemented.  This also helps distinguish this version
               from much older versions which did not have the -v
               flag.  Also the original test file foo which contained
               the string  "abc" (with no newline) was renamed file1.

     SEE ALSO
          shs(1), stat(2), lstat(2)

     FILES
          ${DESTDIR}/file1    alternate test file location
          ${DESTDIR}/file2    alternate test file location

          The typical value of ${DESTDIR} is /usr/local/lib/md5, or
          /usr/local/lib.

     AUTHOR
          Much of this code was written, re-written or modified by:

              Landon Curt Noll     ({chongo,noll}@{toad,sgi}.com)  /\../\

          Part of this code code is based on code by Peter C. Gutmann.

     NOTICE
          LANDON CURT NOLL DISCLAIMS ALL WARRANTIES WITH REGARD TO
          THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
          MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL LANDON CURT
          NOLL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
          DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
          USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
          NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
          CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

          Parts of this code are:

          Copyright (C) 1990, RSA Data Security, Inc. All rights
          reserved.

          License to copy and use this software is granted provided
          that it is identified as the "RSA Data Security, Inc. MD5
          Message- Digest Algorithm" in all material mentioning or
          referencing this software or this function.

          License is also granted to make and use derivative works
          provided that such works are identified as "derived from the
          RSA Data Security, Inc. MD5 Message-Digest Algorithm" in all
          material mentioning or referencing the derived work.

          RSA Data Security, Inc. makes no representations concerning
          either the merchantability of this software or the
          suitability of this software for any particular purpose.  It
          is provided "as is" without express or implied warranty of
          any kind.

          These notices must be retained in any copies of any part of
          this documentation and/or software.

     BUGS
          The command:

               md5 -s '/\"O/\'

          writes to stdout, the following line:

               ae8b1f8db9eaa95693164bd224291da0 "/\"O/\"

          The string written in double quotes by -s may not be a valid
          string according to C or shell syntax.