my %hash2 ;
my @keys_origin = keys %hash_origin ;
@hash2{@keys_origin} = (0) x @keys_origin ;
foreach ( @keys ) {
	my $key = $_ ;
	if ( exists $hash2{ $key } ) {
		$hash2{ $key } += $hash_origin{ $key } ;
	}
}
print Dumper( \%hash2 ) ;
__END__
$VAR1 = {
          'key3' => 0,
          'key2' => 3,
          'key1' => 2
        };