DragonFly On-Line Manual Pages

MD5(1)                 DragonFly General Commands Manual                MD5(1)

NAME
     md5, sha1, sha256, sha512, rmd160 - calculate a message-digest
     fingerprint (checksum) for a file

SYNOPSIS
     md5 [-pqrtx] [-b offset] [-e offset] [-s string] [file ...]
     sha1 [-pqrtx] [-b offset] [-e offset] [-s string] [file ...]
     sha256 [-pqrtx] [-b offset] [-e offset] [-s string] [file ...]
     rmd160 [-pqrtx] [-b offset] [-e offset] [-s string] [file ...]

DESCRIPTION
     The md5, sha1, sha256, sha512 and rmd160 utilities take as input a
     message of arbitrary length and produce as output a "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, SHA-1, SHA-256, SHA-512 and RIPEMD-160
     algorithms are 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.

     The MD5 and SHA-1 algorithms are vulnerable to practical collision
     attacks.

     The following options may be used in any combination and must precede any
     files named on the command line.  The hexadecimal checksum of each file
     listed on the command line is printed after the options are processed.

     -b offset
             When processing file(s), use the specified begin and/or end
             (below) instead of processing each file in its entirety.  Either
             option can be omitted.  Both begin- and end-offsets can be
             specified as just a number (of bytes) or be followed by K, M, or
             G to mean that the number is to be multiplied by 1024 once,
             twice, or thrice respectively.  For example, to start at 512, you
             can use -b 512 or -b 0.5K.

             The use of offsets is implemented using mmap() and will only work
             on regular files and mmap-able devices.

             If the beginning offset is negative, its absolute value is
             subtracted from the file's size.  Zero thus means the very
             beginning of each file, which is also the default if the option
             is omitted entirely.

     -e offset
             If the end-offset is not positive, its absolute value is
             subtracted from the file's size.  Zero thus means the very end of
             each file, which is also the default if the option is omitted
             entirely.

     -s string
             Print a checksum of the given string.

     -p      Echo stdin to stdout and append the checksum to stdout.

     -q      Quiet mode -- only the checksum is printed out.  Overrides the -r
             option.

     -r      Reverses the format of the output.  This helps with visual diffs.
             Does nothing when combined with the -ptx options.

     -t      Run a built-in time trial.

     -x      Run a built-in test script.

EXIT STATUS
     The md5, sha1, sha256, sha512 and rmd160 utilities exit 0 on success, and
     EX_NOINPUT (66) if at least one of the input files could not be read or
     invalid offsets were specified.  A mistake with command line arguments
     results in EX_USAGE (64).

SEE ALSO
     cksum(1), mmap(2)

     R. Rivest, The MD5 Message-Digest Algorithm, RFC 1321.

     J. Burrows, The Secure Hash Standard, FIPS PUB 180-1.

     D. Eastlake and P. Jones, US Secure Hash Algorithm 1, RFC 3174.

     RIPEMD-160 is part of the ISO draft standard "ISO/IEC DIS 10118-3" on
     dedicated hash functions.

     Secure Hash Standard (SHS):
     http://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf.

     The RIPEMD-160 page:
     http://www.esat.kuleuven.ac.be/~bosselae/ripemd160.html.

ACKNOWLEDGMENTS
     This program is placed in the public domain for free general use by RSA
     Data Security.

     Support for SHA-1 and RIPEMD-160 has been added by Oliver Eikemeier
     <eik@FreeBSD.org>.

DragonFly 5.9-DEVELOPMENT       January 9, 2021      DragonFly 5.9-DEVELOPMENT