utils-dev/random.sh

   1 #!/bin/sh
   2 # ---------------------------------------------------------------------------
   3 # Multi-Phasic Applications: SquirrelJME
   4 #     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
   5 #     Copyright (C) Multi-Phasic Applications <multiphasicapps.net>
   6 # ---------------------------------------------------------------------------
   7 # SquirrelJME is under the GNU General Public License v3, or later.
   8 # See license.mkd for licensing and copyright information.
   9 # ---------------------------------------------------------------------------
  10 # DESCRIPTION: Outputs some random bytes as hexadecimal
  11
  12 # Force C locale
  13 export LC_ALL=C
  14
  15 # Directory of this script
  16 __exedir="$(dirname -- "$0")"
  17
  18 # Need count?
  19 if [ "$#" -le "0" ]
  20 then
  21         echo "Usage: $0 (count)"
  22         exit 1
  23 fi
  24
  25 # If outputting no bytes, ignore
  26 __count="$1"
  27 if [ "$__count" -le "0" ]
  28 then
  29         exit 0
  30 fi
  31
  32 # Real random source, if it exists
  33 if [ -c /dev/urandom ] || [ -c /dev/random ]
  34 then
  35         # Unblocked
  36         (if [ -c /dev/urandom ]
  37         then
  38                 dd if=/dev/urandom "bs=$__count" count=1
  39
  40         # Normal
  41         else
  42                 dd if=/dev/random "bs=$__count" count=1
  43         fi) 2> /dev/null | hexdump -x |
  44                 sed 's/^[0-9a-fA-F]\{1,\}//g' | tr -d ' ' | tr -d '\n' | tr -d '\t'
  45
  46         # End with newline
  47         echo ""
  48
  49 # Not really random, but something
  50 else
  51         # Seed the random number generator and get a value
  52         __seed="$( (echo -n $$ & echo -n $!; date +%s & echo -n $!) |
  53                 tr -d ' ' | tr -d '\n' | sed 's/[^0-9]*//g' | cut -c 1-8)"
  54
  55         # Loop
  56         __i=0
  57         while [ "$__i" -lt "$__count" ]
  58         do
  59                 # Calculate a value
  60                 __a="$(expr $__seed '*' 1337 | cut -c 1-8)"
  61
  62                 # Set new seed
  63                 echo -n "" &
  64                 __pid="$!"
  65                 __seed="$__a$__pid"
  66
  67                 # Add all of the seed values together
  68                 __rest="$__seed"
  69                 __xa="0"
  70                 __xb="1"
  71                 __j="0"
  72                 while [ -n "$__rest" ]
  73                 do
  74                         __char="$(echo "$__rest" | cut -c 1)"
  75
  76                         # Add to A or B?
  77                         if [ "$__j" -eq "0" ]
  78                         then
  79                                 __xa="$(expr "$__xa" + "$__char")"
  80                                 __j="1"
  81                         else
  82                                 __xb="$(expr "$__xb" + "$__char")"
  83                                 __j="0"
  84                         fi
  85
  86                         # Cut character
  87                         __rest="$(echo "$__rest" | cut -c 2-)"
  88                 done
  89
  90                 # Modulo 16 for hex
  91                 __ya="$(expr $__xa % 16)"
  92                 __yb="$(expr $__xb % 16)"
  93
  94                 # Echo individual hex characters
  95                 for __q in $__ya $__yb
  96                 do
  97                         case $__q in
  98                                 10) printf '%s' "a";;
  99                                 11) printf '%s' "b";;
 100                                 12) printf '%s' "c";;
 101                                 13) printf '%s' "d";;
 102                                 14) printf '%s' "e";;
 103                                 15) printf '%s' "f";;
 104                                 *) printf '%s' "$__q";;
 105                         esac
 106                 done
 107
 108                 # Increment
 109                 __i="$(expr $__i + 1)"
 110         done
 111
 112         # End with newline
 113         echo ""
 114 fi
 115