ose;
use Digest::SHA qw/hmac_sha256/;
use Digest::MD5 qw/md5_hex/;
use MIME::Base64::URLSafe;
use JSON;
use Carp qw/croak/;
use namespace::autoclean;
has canvas_param => (
isa => 'Str',
is => 'ro'
d) = split('\.', $facebook_data);
my $sig = urlsafe_b64decode($encoded_sig);
my $data = decode_json(urlsafe_b64decode($payload));
my $expected_sig = hmac_sha256($payload, $app_secret);
if ($sig