its utxo model.
You send the whole balance and the "change" gets transferred to a new address of your wallet.
So the change is auto protected since its having a new address than before.
But the address you initiated it from, its public key is written in the chain for everyone to︀ see (and qc can calc back the private key from it).
The bitcoin addresses are︁ not public keys but derived by one way functions so you cant calc back from︂ this to its private key (unless its public key has been revealed).
Maybe this changes︃ some day tho.
You send the whole balance and the "change" gets transferred to a new address of your wallet.
So the change is auto protected since its having a new address than before.
But the address you initiated it from, its public key is written in the chain for everyone to︀ see (and qc can calc back the private key from it).
The bitcoin addresses are︁ not public keys but derived by one way functions so you cant calc back from︂ this to its private key (unless its public key has been revealed).
Maybe this changes︃ some day tho.