How does it work:
1. Creating "subwallet address":
The new btc addresses would be created from the "master address" with the following theoretical formula "master private key" + "master passphrase"
(this is your unique key) = "new btc address" which for reference we will call "subwallets address" .
why does there have to be a deterministic relationship between the master private key and what you later refer to add the subwallet private key?
2. A transaction signed by the "master privatekey" + "subwallet privatekey" will be sent to the blockchain announcing that the created bitcoin address
"subwallet address" is your property, this operation cannot be replaced and will be permanently saved in it. that we will call "owner's btc book"
what's the incentive for people running full nodes to want to store the "owner's btc book"? it's not making them any money but it will be costing them storage space and overhead. plus, there's no limit to the size it could grow and it never gets smaller.
-for transactions greater than "1 btc" it is necessary to sign with the "master privatekey" + "subwallet privatekey", this will be compared with the
owner's btc book.
-for transactions smaller than "1 btc" that we will call "subtransaction", only the signature of the "privatekey subwallet" is necessary (as it currently works).
Another problem with this idea is the arbitrary choice of "1btc". What's 1 btc worth? The blockchain doesn't know. It could be worth alot but it might not be worth much. That depends on its relationship to the US Dollar for example, something the blockchain doesn't know anything about. As if that issue weren't enough, there's the other issue that even if you have some way of adjusting "1btc", the value of "1btc" might have different meaning to different bitcoin users. So while 0.1 btc might be alot for me, it might mean very little to someone else. Your one size fits all valuation doesn't make much sense in that regard and is not useful as a security procedure for that reason also.