use Digest::MD5;
    my $md5    = Digest::MD5->new;
    my $remote = $ENV{ REMOTE_ADDR } . $ENV{ REMOTE_PORT };
    my $unique = $md5->md5_base64( time, $$, $remote, $email );
    $unique    =~ tr|+/=|-_.|; # Make non-word characters URL-friendly
[download]

That will generate a unique, URL-friendly 22 character string for them.

Cheers,
Ovid

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(Note: this is very close to the scheme that Ovid posted seconds before above.)

#!/usr/bin/perl -wT
use strict;

sub passgen {           # sub to gen random passwd
  my $len = shift;      # one integer param for length of passwd

  my @chars = (0..9,'A'..'Z','a'..'z');          # which chars are leg
+al
  my $passwd;
  $passwd .= $chars[rand @chars] for (1..$len);  # make the passwd
  return $passwd;
}

#### Testing Loop ####
for my $len (6..9) {  # for various lengths
  for my $i (1..3) {  # try it a few times
    my $passwd = passgen($len);
    print "$i.)L=$len randpass = '$passwd'\n";
  }
  print "\n";
}

=sample output
1.)L=6 randpass = 'rqLb1V'
2.)L=6 randpass = 'zdrG8f'
3.)L=6 randpass = '5Rl2mA'

1.)L=7 randpass = 'Z4AiWxX'
2.)L=7 randpass = 'gnx6RFy'
3.)L=7 randpass = 'HbZJ6Zw'

1.)L=8 randpass = 'yp5euXPx'
2.)L=8 randpass = 'JZXNkGui'
3.)L=8 randpass = 'oaVlhw1f'

1.)L=9 randpass = 'DcFWjoSie'
2.)L=9 randpass = 'YMZ5mXOM4'
3.)L=9 randpass = 'm6Kgo8HJu'
[download]

-Blake

#!/usr/bin/perl -w

my $gmtime =join '', gmtime;
my $time = time;
my $rand = rand time;
my @salt = ('.','/','A'..'Z',0..9,'a'..'z');
my $salt = join '', (@salt)[rand @salt, rand @salt];

my $uniquetempass = crypt( $gmtime.$rand.$time, $salt);


print 'gmtime ', $gmtime, "\n";
print 'time ',$time,"\n";
print 'rand ', $rand,"\n";
print 'salt ', $salt, "\n";
print $uniquetempass, "\n";
[download]

 
___crazyinsomniac_______________________________________
Disclaimer: Don't blame. It came from inside the void
perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"

This begs the question - where are you going to store the unique string so when (if) the user comes back you can match the entered string?

If you're using some type of flat file store, or in-memory storage - all the above should work fine. However, if your using a database, most rdbms all ready have this capability built in. Sybase has identity columns and Oracle has sequences (Mysql has ??) these are guarenteed (sp?) to be unique and can be most useful for your situtation.

-derby