"Security implications"? Surely it would be just as secure as everyone's favourite language: Perl.

That aside, here's an implementation (complete with syntax checking) for the mini-est language I can think of.

$_ = <>;
die "Syntax Error\n" unless m/^[10]$/;
die "Syntax Error\n" if defined <>;
exit $_;
[download]

I'll leave it up to you to work out what the valid input is.