How do you go backwards? You don't know the length of the last element/position of the last tag unless you work forward from the front, as far as I can see.
BER is complicated, but no more complicated than rfc-822 style headers, which are also poorly parsed by ad-hoc parsers, and were a wide source of vulnerabilities.
BER is complicated, but no more complicated than rfc-822 style headers, which are also poorly parsed by ad-hoc parsers, and were a wide source of vulnerabilities.