rank your "uncrackable" software protection

[mcp]

You can not proof it because nobody knows which attacks appear tomorrow. Just suppose in 10 years quantum computers appear. And almost all current crypto would be trash.
Years ago DES looks uncrackable. Nowadays it is weak.
The same to RSA. Ten years ago RSA-512 was strong. Now it is weak.
Could you make the RSA less or equal to 512 bits which we can not crack? Sure, you cant. Most algos add more rounds to be stronger or increase key sizes or other params.

Of course there is exactly one crypto scheme which is provably secure against any attack (OTP) but I was just arguing against the claim of being able to break any instance of those problems. And that's obviously not true.

HE libraries are very rough. Limited in the operations to Add and Mul in most. Also, it is hard to imagine the use cases which help to protect applications. Could you describe any?
To operate in HE you need both numbers encrypted with private key. To decrypt result you need also public key. Would you store both keys in the software? Or how do you plan to make protection?

Yap, there's a reason why not "everything" just simply switches to (F)HE schemes. There are multiple reasons: a) it is slow as hell b) full HE isn't trivial, most libraries limit themselves to addition and/or multiplication as you said.
Take for example the use case that you want to compute something which must not be revealed to the public, still the computation has to be made on every consumer's device, and the consumers must not know how the computations inner workings look like.
Then again, the weak points of FHE are the input and output values: if these are to be used in other non-HE parts of the program, these clearly must be decrypted.

As always in security, you have to be aware of the "attacker model": FHE per se cannot be used to create any kind of "unbreakable" protection, and no sane person would ever claim that. On the other hand, I strongly disagree with the statement that "everything made by man can be broken". That's too broad of a statement and is simply not true in general.

[Syoma]

Originally Posted by mcp

I strongly disagree with the statement that "everything made by man can be broken".

Sure, it can be. But nobody guarantees it will work after that or even be valid.