The answers to this question state that reusing the same address for spending several times seriously compromises my private key so that should never be done. However, isn't this exactly what is happening when I reattach a transaction that was not picked up by the network (which is obviously encouraged)? Isn't it the case that with every reattach attempt my private key becomes easier to "guess"?
The data signed in a transaction don't include parent and branch transaction hash.
So when you reattach a transaction the signature is unchanged. It means that the portion of the private key disclosed when you reattach is exactly the same as the portion disclosed during first "attach to tangle".
This design choice (to not include parent and branch transaction in signed data) make possible several useful things :
- anyone can reattach a transaction to the tangle
- PoW delegation
- re-attachinging don't disclose new portion of the private key