NAME

       sharand - generate cryptographically secure pseudo random file

SYNOPSIS

           sharand key
           sharand key count-of-bytes

DESCRIPTION

       SHA1-RANDOM generates cryptographically secure pseudo random files which should not be
       compressible by any algorithm that does not know the key used to generate it. Without
       knowing the key, it is believed to be impossible to compress this file.

       The command:

          sharand key

       prints the SHA1 hash of the key, which can be any ASCII string.  If the string has spaces,
       then enclose it in quotes.

       Command:

          sharand key n

       works as above and also creates the file "sharand.out" with length n bytes containing
       cryptographically secure pseudo random numbers. Given all but one bit of the file, it is
       not possible to guess the remaining bit with probability greater than 1/2 unless you know
       the key.

       The output is a series of 20 byte strings, x[1], x[2], ... x[n/20] such that:

         x[i] = SHA1(x[i-1] + key)

       where x[0] is a string of 0 bytes, and + denotes concatenation.

OPTIONS

       None.

EXAMPLES

       Basic use:

         $ sharand abc 50

         Key hash = A9 99 3E 36 47 06 81 6A BA 3E 25 71 78 50 C2 6C 9C D0 D8 9D
         Wrote sharand.out (50 bytes)

       The contents of sharnad.out

         $ od -x sharand.out

         7D DF 37 9E  DB 9F 0E 14  1F 6D AD EF  EC 28 F0 60
         2B 2A 76 A8  49 54 13 F2  6E DA 0F 19  CD D9 26 6C
         46 8A 2D 17  8B 76 24 C0  0D D1 80 4F  E7 22 6C 2A
         9A C9

ENVIRONMENT

       None.

FILES

       Program's output is written to "sharnad.out".

STANDARDS

       "US Secure Hash Algorithm 1 (SHA1)" http://www.rfc-editor.org/rfc/rfc3174.txt

SEE ALSO

       crypt(1)

AUTHORS

       Program was written by Matt Mahoney <matmahoney@yahoo.com>

       This manual page was written by Jari Aalto <jari.aalto@cante.net>.  Released under license
       GNU GPL version 2 or (at your option) any later version. For more information about
       license, visit <http://www.gnu.org/copyleft/gpl.html>.