diff options
| author | Antoine Riard <ariard@student.42.fr> | 2019-12-10 18:08:21 -0500 |
|---|---|---|
| committer | Antoine Riard <ariard@student.42.fr> | 2019-12-18 13:31:32 -0500 |
| commit | f41d58966995fe69df433fa684117fae74a56e66 (patch) | |
| tree | d33b90c0f525fcead4a12777766da32b60fa0e3a | |
| parent | 3d6752779f0504e6435fe682f0c06c60b5c4c33b (diff) | |
Document better -keypool as a look-ahead safety mechanism
If after a backup, an address is issued beyond the initial
keypool range and none of the addresses in this range
is seen onchain, if a wallet is restored from backup, even in
case of rescan, funds may be loss due to the look-ahead
buffer not being incremented and so restored wallet not detecting
onchain out-of-range address as derived from its seed.
This scenario is theoretically unavoidable due to the requirement
of the keypool to have a max size. However, given the default
keypool size, this is unlikely. Document better keypool size
implications to avoid user setting a too low value.
| -rw-r--r-- | src/wallet/init.cpp | 2 | ||||
| -rw-r--r-- | src/wallet/scriptpubkeyman.h | 5 |
2 files changed, 6 insertions, 1 deletions
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp index dd0d2ffbd7..2ebc9aba39 100644 --- a/src/wallet/init.cpp +++ b/src/wallet/init.cpp @@ -46,7 +46,7 @@ void WalletInit::AddWalletOptions() const gArgs.AddArg("-fallbackfee=<amt>", strprintf("A fee rate (in %s/kB) that will be used when fee estimation has insufficient data. 0 to entirely disable the fallbackfee feature. (default: %s)", CURRENCY_UNIT, FormatMoney(DEFAULT_FALLBACK_FEE)), ArgsManager::ALLOW_ANY, OptionsCategory::WALLET); - gArgs.AddArg("-keypool=<n>", strprintf("Set key pool size to <n> (default: %u)", DEFAULT_KEYPOOL_SIZE), ArgsManager::ALLOW_ANY, OptionsCategory::WALLET); + gArgs.AddArg("-keypool=<n>", strprintf("Set key pool size to <n> (default: %u). Warning: Smaller sizes may increase the risk of losing funds when restoring from an old backup, if none of the addresses in the original keypool have been used.", DEFAULT_KEYPOOL_SIZE), ArgsManager::ALLOW_ANY, OptionsCategory::WALLET); gArgs.AddArg("-maxtxfee=<amt>", strprintf("Maximum total fees (in %s) to use in a single wallet transaction; setting this too low may abort large transactions (default: %s)", CURRENCY_UNIT, FormatMoney(DEFAULT_TRANSACTION_MAXFEE)), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST); gArgs.AddArg("-mintxfee=<amt>", strprintf("Fees (in %s/kB) smaller than this are considered zero fee for transaction creation (default: %s)", diff --git a/src/wallet/scriptpubkeyman.h b/src/wallet/scriptpubkeyman.h index 6ed9a4787a..31547ec4d4 100644 --- a/src/wallet/scriptpubkeyman.h +++ b/src/wallet/scriptpubkeyman.h @@ -72,6 +72,11 @@ std::vector<CKeyID> GetAffectedKeys(const CScript& spk, const SigningProvider& p * keys (by default 1000) ahead of the last used key and scans for the * addresses of those keys. This avoids the risk of not seeing transactions * involving the wallet's addresses, or of re-using the same address. + * In the unlikely case where none of the addresses in the `gap limit` are + * used on-chain, the look-ahead will not be incremented to keep + * a constant size and addresses beyond this range will not be detected by an + * old backup. For this reason, it is not recommended to decrease keypool size + * lower than default value. * * The HD-split wallet feature added a second keypool (commit: 02592f4c). There * is an external keypool (for addresses to hand out) and an internal keypool |