So point0 is of the form of an uncompressed pubkey. That's fine, but for forwards compatibility, the multiply function should multiply a point with a bignum, not a pubkey with a bignum. I'm not really sure what a "Point" is ultimately going to be in bitcore since no such C++ code for a Point exists yet, but in the meantime maybe this function can be called something like MultiplyUncompressed? That is the same rationale used to call the "add" function "addUncompressed".

Of course ultimately I think both add and multiply belong on entirely different classes ... they should be on Point rather than Key.