Der default values

DER encoder should not include values that are equual to defaults.

Ref http://luca.ntop.org/Teaching/Appunti/asn1.html:

    DER encoding. Constructed. Contents octets are the same as the BER
    encoding, except that if the value of a component with the DEFAULT
    qualifier is the default value, the encoding of that component is not
    included in the contents octets.
Yes, this one is tricky and only way to compare complex things is comparing it's serialized form.

For primitives this kind of check would work however, so optimisations are possible.