You could do something like:

use strict;

my $to_parse='allow:test1, "@test2" deny:test3,test4 password:"123   4
+56"';
my ($allow,$deny,$password)= $to_parse=~/([^:]+?)deny:([^:]+?)password
+:([^:]+)/;
my $result_hash={};
my @allowlist=map {/([^"]+)/} (split /\s*,\s*/ , $allow);
if (scalar (@allowlist) == 1) {
  $result_hash->{"allow"}=$allowlist[0];
  } else {
  $result_hash->{"allow"}=\@allowlist;
  }
print $result_hash->{"allow"} ."\n";
print $result_hash->{"allow"}->[1];
# and similar for deny and password
[download]

There are obvious ways of improving this: putting in a better regexp with lookahead matches, putting the stanzas (allow, deny, ...) in a hash or array and iterate over that one etc., but this should give you an idea on how to proceed.

CU
Robartes-

Update:After submitting, I saw jj808's solution - that has the better regexp I mentioned, and the commas between "" issue he mentions is also present in my code.