#!/usr/bin/perl -w

use strict;
use Digest::HMAC;
use Digest::SHA1;
use Digest::MD5;

my %hashes = ( 'OAKLEY_SHA' => 'Digest::SHA1',
	       'OAKLEY_MD5' => 'Digest::MD5'
	       );

my $nonce_i = $ENV{"NONCE_I"}; 
my $nonce_r = $ENV{"NONCE_R"};
my $hashtype = $ENV{"HASHTYPE"};
my $connection = $ENV{"CONN_NAME"};

$nonce_i =~ s/0x(.*)/$1/; $nonce_i = pack('H*', $nonce_i);
$nonce_r =~ s/0x(.*)/$1/; $nonce_r =pack('H*', $nonce_r);

my $key = get_secret($connection);

my $hash_name = $hashes{$hashtype};
if (!defined($hash_name)) {
    print "ERROR=unsupported hash type: $hashtype\n";
    exit(1);
}

my $hmac = Digest::HMAC->new($key, $hash_name);
$hmac->add($nonce_i);
$hmac->add($nonce_r);
my $skeyid = $hmac->hexdigest;

print "SKEYID=0x$skeyid\n";

sub get_secret {
    return "the big hidden secret noone can guess";
}