#!/usr/local/bin/perl

$USAGE = "
SYNOPSIS: generate a random string for passwords
USAGE: mkpw LENGTH LEVEL NUMPASS
Notes:
   LENGTH >0 or 4 default
GPL(C) 1999-11-27 http://www.cs.albany.edu/~mosh
";

my $pwlen = shift; $pwlen = 4 if $pwlen < 4;
my $level = shift || 1;
my $numpw = shift || 1;

my @pwchar1 = split( //, "bcdfghjklmnpqrstvwxyz");
my @pwchar2 = split( //, "/=-.;" );
my @pwchar3 = split( //, "aeiou");
my @pwchar4 = split( //, "0123456789");

my $kindex = 0;
my $krandom = "$ENV{HOME}/knuth/krandoms";
my @krandom;
if( open( RAND, $krandom ) ){
    @krandom = <RAND>;
    foreach( @krandom ){ chomp; }
    close RAND;
}else{
    warn "
        Cannot read krandom file=$krandom.
        krandom generator derived from
        Knuth's http://Sunburn.Stanford.EDU/~knuth/programs/rng.c
        or follow this link http://www-cs-faculty.Stanford.EDU/~knuth\n";
    srand( reverse (time()+ $$) ) ; # broken srand, size of seed matters.
    rand();  # something wrong with first call to rand?
}

while( $numpw-- ){
    print mkpw($pwlen),"\n";
}

# end of main.

# ZZ: Windows/perl/rand: call less then than once/second.
# srand( reverse (time()+ $$) ) ; # broken srand, size of seed matters.
# rand();  # something wrong with first call to rand?

sub mkpw {
    my $pwlen = shift || 4;
    my @otpw;
    my($i);
    for( $i = 0; $i < $pwlen/2 ; $i++ ){
        push( @otpw,  $pwchar1[ krandom($#pwchar1) ] );
        push( @otpw,  $pwchar2[ krandom($#pwchar2) ] ) if $level > 2;
        push( @otpw,  $pwchar3[ krandom($#pwchar3) ] ) unless $level > 2;
        push( @otpw,  $pwchar3[ krandom($#pwchar3) ] ) if $level > 1;
    }
    for( $i = 0; $i < 1 ; $i++ ){
        push( @otpw,  $pwchar2[ krandom($#pwchar2) ] );
    }
    for( $i = 0; $i < 2 ; $i++ ){
        push( @otpw,  $pwchar4[ krandom($#pwchar4) ] );
    }
    return join('',@otpw);
}

sub krandom {
    my $max = shift;
    my $val;
    $max++;
    if( $#krandom ){
        $kindex += 1 + time();
        $val = $krandom[ $kindex % $#krandom ] % $max;
        # warn "ki=$kindex,max=$max,val=$val,kmax=$#krandom\n";
    }else{
        $val = rand($max);
    }
    return $val;
}