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I'm concerned about non-web wallets that discard private keys after use.
- Web wallets - share addresses between users, so the user can consider all private keys to be immediately discarded.
- Deterministic wallets - All receiving addresses can be regenerated at any time and so it's impossible to lose funds that are transferred to previous addresses even ancient ones.
- Paper wallets - are essentially permanent addresses, so no issue there beyond user-error.
So this just leaves me with the question of how many non-deterministic wallets discard previous addresses (including change addresses)?
It has been stated that "the BIP 0032 standard for Hierarchical Deterministic Wallets is used by all good wallets as of 2019.". Should I take that assessment literally with regard to non-web wallets, that non-deterministic wallets are uncommon even on mobile?
1Why would you ever discard keys? – Anonymous – 2019-04-04T22:26:16.190
@Anonymous change addresses may not be said to serve a useful purpose once the coins are signed out to another address. change addresses are not created for the express purpose of receiving funds and therefore some wallets may assume that no funds will be received at that address and dispose of the address to save memory/disk space. – Brenda.ZMPOV – 2019-04-05T18:47:15.230
They’re 32 bytes. Nobody is discarding them to save space. – Anonymous – 2019-04-05T18:48:02.970
@Anonymous
– Brenda.ZMPOV – 2019-04-05T18:55:30.310Once that payment is made, the receiving party has no reason to retain the data for the address (technical details simplified) and may discard it.at least one person disagrees with you.The Bitcoin Wiki has never been a particularly solid source of information at the best of times. No software has ever operated like this. – Anonymous – 2019-04-05T18:56:52.493
I think that statement may be more about the fact that the owner of the receiving wallet may decide to move on to other wallet software, and stop caring enough about the old wallet to retain the keys. Thus, while no software will intentionally discard keys, the sender can't assume the receiver person will forever have access to old keys. – Pieter Wuille – 2019-04-06T03:25:09.400