DESCRIPTION

     The sha256 utility takes as input a message of arbitrary length and pro-
     duces as output a ``fingerprint'' or ``message digest'' of the input.  It
     is conjectured that it is computationally infeasible to produce two mes-
     sages having the same message digest, or to produce any message having a
     given prespecified target message digest.  The 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.

     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.

     -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.

DIAGNOSTICS

     The sha256 utility exits 0 on success, and 1 if at least one of the input
     files could not be read.

SEE ALSO

     cksum(1), md5(1)

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

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

     Secure Hash Standard (SHS): http://csrc.nist.gov/cryptval/shs.html.

ACKNOWLEDGMENTS

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

BSD                              June 6, 2004                              BSD