So you can say... with 100% certainty... that there are no "bugs, glitches, backdoors, ... etc that either allows them to be hacked or they screws up on their own, or both." in RAR software... with it's closed sources? 
And for the record... your method would probably fail the "$5 wrench attack":
And for the record... your method would probably fail the "$5 wrench attack":
I would say I have used WinRar for many several years and it never disappoint me, not even once.
All those videos saying WinRar's .rar files can be hacked is fake because they use brute force on negligible passwords like "abc" and "123".
And thank you for bringing up that $5 wrench attack because I came across such argument while writing my article.
Here's the thing, can anyone using hardware wallet be safe from the "$5 wrench attack"?
Here's an honest + objective answer... NO.
And is it better to use my approach vs hardware wallet? Yes.
Why? Using hardware wallet is a physical dead giveaway that you have bitcoin and/or other cryptocurrencies.
Using digitally-encrypted private keys that I suggested is not, unless you try to brag and boost that you are rich because you have plenty of cryptocurrencies, in which case you are the security risk, not my approach.