This is assuming you have the "Amount Key"?
No. The equality
sum(in)-sum(out)-fee=0 is independently verified by every node or any observer without any key.
(...)
Else, you could have the problem of being too opaque, because the network peers would not be able to check if moneros were being created at will.
This is a really big deal. If/once confidential transactions are integrated into Monero, it will be the best cryptocurrency hands down mathematically possible.
The only way to improve upon it would be to enhance it's transaction per second scaling through some yet-unheard-of mathematics, but it's likely such a radical shift would break all the excellent privacy features we have built up so far.
We can handle a theoretical 1600 tx/sec now; perhaps if a way to scale easily to tens of thousands or hundreds of thousands were proposed it would be compatible with the Monero implementation.
As well, we aren't sure if 1600 tx/sec will even be our final maximum (may improve over time with upgrades to software/hardware) and even if it is, that's good enough to serve as a backbone for a giant international settlement mechanism. Visa does 40,000 tx/sec, but by the 2030's we may not be using Monero to buy coffee with - it's possible that it will serve as a financial backbone for other centralized sidechains and centralized/national/NWO currencies. I think that most people wouldn't have as much of a problem with US Dollars, even inflationary ones if the Federal Reserve issued a view key each year and said: "
As you can see, the US Dollar is currently being backed by 34 ore each. If inflation proceeds as planned, considering our mining operations, next year the dollar will each be backed by 33.8 ore each." (or whatever an atomic unit of Monero is designated as in the 2030's
)
That was based on smooth's calculations (with an i7-2600k using 4 cores IIRC). I don't know how he got to 2.5ms per tx, but I assume it's accurate. Unless CPUs hit some kind of brick wall, it's a certainty that that number will improve (obviously that's for a single CPU desktop as well); the 2600k is also 4 series behind the present (or something, Intel has dorked it up).
I believe bandwidth and hard drive space are much more pressing concerns for "big" usage.
A 5 input, 5 ouput, 5 mixin Tx is about 2kB. 1,600 TPS at that made up average size would equal:
25.54 mbps up/down bandwidth (assuming receive/send each Tx once)
~269 GB / day in storage
~96 TB / year
I said somewhere that I thought 100-200 (or more) TB SSDs would be available in ~8 years, so the storage might not actually be that bad. Bandwidth will surely come a long way in 8 years too, and 25.54mbps will likely be inconsequential (which was an idealized case of course).
What's my point? Basically it is that CPUs seem to be 5-10 years "ahead of the curve" as far as cryptocurrency requirements go.