The following code, taken from here, worked for me!
# Either build your data as a hashref
my $hashref = {
username => someusername,
etc => ...,
};
# or assign a reference to a hash
my %data = (username => someusername, etc => ...);
my $hashref = \%data;
# Then pass it off
my $valid = verify($hashref);
# You can also pass like so
my $valid = verify(\%data);
# Then, in your verify sub:
sub verify {
my $ref = shift;
# do something with your data
$ref->{'username'} =~ /yourregex/;
return $something;
}