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

NAME
     md5, sha1, sha224, sha256, sha384, sha512, sha512t256, rmd160, skein256,
     skein512, skein1024, md5sum, sha1sum, sha224sum, sha256sum, sha384sum,
     sha512sum, sha512t256sum, rmd160sum, skein256sum, skein512sum,
     skein1024sum - calculate a message-digest fingerprint (checksum) for a
     file

SYNOPSIS
     md5 [-pqrtx] [-c string] [-s string] [file ...]

     md5sum [-pqrtx] [-c file] [-s string] [file ...]

            (All other hashes have the same options and usage.)

DESCRIPTION
     The md5, sha1, sha224, sha256, sha384, sha512, sha512t256, rmd160,
     skein256, skein512, and skein1024 utilities take as input a message of
     arbitrary length and produce as output a "fingerprint" or "message
     digest" of the input.  The md5sum, sha1sum, sha224sum, sha256sum,
     sha384sum, sha512sum, sha512t256sum, rmd160sum, skein256sum, skein512sum,
     and skein1024sum utilities do the same, but default to the reversed
     format of the -r flag.  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 SHA-224 , SHA-256 , SHA-384 , SHA-512, RIPEMD-160, and SKEIN
     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.

     -b      Make the -sum programs separate hash and digest with a blank
             followed by an asterisk instead of by 2 blank characters for full
             compatibility with the output generated by the coreutils versions
             of these programs.

     -c string
             If the program was called with a name that does not end in sum,
             compare the digest of the file against this string.  (Note that
             this option is not yet useful if multiple files are specified.)

     -c file
             If the program was called with a name that does end in sum, the
             file passed as argument must contain digest lines generated by
             the same digest algorithm with or without the -r option (i.e. in
             either classical BSD format or in GNU coreutils format).  A line
             with the file name followed by a colon ":" and either OK or
             FAILED is written for each well-formed line in the digest file.
             If applicable, the number of failed comparisons and the number of
             lines that were skipped since they were not well-formed are
             printed at the end.  The -q option can be used to quiesce the
             output unless there are mismatched entries in the digest.

     -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.  For the -sum versions, this is a nop
             for compatibility with coreutils.

     -x      Run a built-in test script.

EXIT STATUS
     The md5, sha1, sha224, sha256, sha512, sha512t256, rmd160, skein256,
     skein512, and skein1024 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.

EXAMPLES
     Calculate the MD5 checksum of the string "Hello".

           $ md5 -s Hello
           MD5 ("Hello") = 8b1a9953c4611296a827abf8c47804d7

     Same as above, but note the absence of the newline character in the input
     string:

           $ echo -n Hello | md5
           8b1a9953c4611296a827abf8c47804d7

     Calculate the checksum of multiple files reversing the output:

           $ md5 -r /boot/loader.conf /etc/rc.conf
           ada5f60f23af88ff95b8091d6d67bef6 /boot/loader.conf
           d80bf36c332dc0fdc479366ec3fa44cd /etc/rc.conf
           The
           -sum
           variants put 2 blank characters between hash and file name for full compatibility
           with the coreutils versions of these commands.

     Write the digest for /boot/loader.conf in a file named digest.  Then
     calculate the checksum again and validate it against the checksum string
     extracted from the digest file:

           $ md5 /boot/loader.conf > digest && md5 -c $(cut -f2 -d= digest) /boot/loader.conf
           MD5 (/boot/loader.conf) = ada5f60f23af88ff95b8091d6d67bef6

     Same as above but comparing the digest against an invalid string
     ("randomstring"), which results in a failure.

           $ md5 -c randomstring /boot/loader.conf
           MD5 (/boot/loader.conf) = ada5f60f23af88ff95b8091d6d67bef6 [ Failed ]

     If invoked with a name ending in -sum the -c option does not compare
     against a hash string passed as parameter.  Instead, it expects a digest
     file, as created under the name digest for /boot/loader.conf in the
     example above.

           $ md5 -c digest /boot/loader.conf
           /boot/loader.conf: OK

     The digest file may contain any number of lines in the format generated
     with or without the -r option (i.e. in either classical BSD format or in
     GNU coreutils format).  If a hash value does not match the file, FAILED
     is printed instead of OK.

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

BUGS
     All of the utilities that end in `sum' are intended to be compatible with
     the GNU coreutils programs.  However, the long option functionality is
     not provided.

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>.

FreeBSD 13.1-RELEASE-p6          June 29, 2021         FreeBSD 13.1-RELEASE-p6