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Command Section
MD5(1)                  FreeBSD General Commands Manual                 MD5(1)

NAME
     md5, sha1, sha256, sha384, sha512, sha512t256, rmd160 - calculate a
     message-digest fingerprint (checksum) for a file

SYNOPSIS
     md5 [-pqrtx] [-c string] [-s string] [file ...]
     sha1 [-pqrtx] [-c string] [-s string] [file ...]
     sha256 [-pqrtx] [-c string] [-s string] [file ...]
     sha384 [-pqrtx] [-c string] [-s string] [file ...]
     sha512 [-pqrtx] [-c string] [-s string] [file ...]
     sha512t256 [-pqrtx] [-c string] [-s string] [file ...]
     rmd160 [-pqrtx] [-c string] [-s string] [file ...]

DESCRIPTION
     The md5, sha1, sha256, sha384, sha512, sha512t256 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-384,
     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 have been proven to be vulnerable to
     practical collision attacks and should not be relied upon to produce
     unique outputs, nor should they be used as part of a cryptographic
     signature scheme.  As of 2017-03-02, there is no publicly known method to
     reverse either algorithm, i.e. to find an input that produces a specific
     output.

     SHA-512t256 is a version of SHA-512 truncated to only 256 bits.  On
     64-bit hardware, this algorithm is approximately 50% faster than SHA-256
     but with the same level of security.  The hashes are not interchangeable.

     It is recommended that all new applications use SHA-512 or SKEIN-512
     instead of one of the other hash functions.

     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.

     -c string
             Compare the digest of the file against this string.  (Note that
             this option is not yet useful if multiple files are specified.)

     -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, sha512t256 and rmd160 utilities exit 0 on
     success, 1 if at least one of the input files could not be read, and 2 if
     at least one file does not have the same hash as the -c option.

SEE ALSO
     cksum(1), md5(3), ripemd(3), sha(3), sha256(3), sha384(3), sha512(3)

     R. Rivest, The MD5 Message-Digest Algorithm, RFC1321.

     J. Burrows, The Secure Hash Standard, FIPS PUB 180-2.

     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/cryptval/shs.html.

     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
     <[email protected]>.

FreeBSD 11.1-RELEASE-p4         April 22, 2016         FreeBSD 11.1-RELEASE-p4
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