BabyJ723 / repository

OnLinE-MulaH-411

[TIP] ==== Many wallets do not allow for the creation of wallets with more than a 12 word mnemonic phrase. You will notice from the tables above that despite the unique lengths of entropy input, the seed size remains the same (512 bits). From a security perspective, the amount of entropy actually used for the production of HD wallets is roughly 128 bits, which equals 12 words. Providing more than 12 words produces additional entropy which is unnecessary, and this _unused_ entropy is not used for the derivation of the seed in the way that one might intially suspect. From a usability perspective, 12 words is also easier to write down, back up, and store. Many wallets do not allow for the creation of wallets with more than a 12 word mnemonic phrase. You will notice from the tables above that despite the unique lengths of entropy input, the seed size remains the same (512 bits). From a security perspective, the amount of entropy actually used for the production of HD wallets is roughly 128 bits, which equals 12 words. Providing more than 12 words produces additional entropy which is unnecessary, and this _unused_ entropy is not used for the derivation of the seed in the way that one might initially suspect. From a usability perspective, 12 words is also easier to write down, back up, and store. ==== [[mnemonic_passphrase]] @@ -478,7 +478,7 @@ However, the little web store became quite successful and attracted many orders Gabriel's HD wallet offers a much better solution through the ability to derive public child keys without knowing the private keys. Gabriel can load an extended public key (xpub) on his website, which can be used to derive a unique address for every customer order. Gabriel can spend the funds from his Trezor, but the xpub loaded on the website can only generate addresses and receive funds. This feature of HD wallets is a great security feature. Gabriel's website does not contain any private keys and therefore does not need high levels of security. To export the xpub, Gabriel uses the web-based software in conjunction with the Trezor hardware wallet. The Trezor device must be plugged in for the public keys to be exported. Note that hardware wallets will never export private keys&#x2014;those always remain on the device. <<export_xpub>> shows the web interface Gabriel uses to export the xpub. To export the xpub, Gabriel uses the Trezor Suite desktop app in conjunction with the Trezor hardware wallet. The Trezor device must be plugged in for the public keys to be exported. Note that hardware wallets will never export private keys&#x2014;those always remain on the device. <<export_xpub>> shows what Gabriel sees in Trezor Suite when exporting the xpub. [[export_xpub]] .Exporting an xpub from a Trezor hardware wallet image::images/mbc2_0512.png["Exporting the xpub from the Trezor"] Gabriel copies the xpub to his web store's bitcoin shop software. He uses _BTCPay Server_, which is an open source web-store for a variety of web hosting and content platforms. BTCPay Server uses the xpub to generate a unique address for every purchase. ((("", startref="gabrielfivetwo"))) ===== Account Discovery and Management Gabriel's business is flourishing. He has provided his extended public key (xpub) to _BTCPay Server_, which is generating unique addresses for customers to his website. Every time a customer to Gabriel's website clicks on the "Checkout" button with a specified payment modality (in this case, bitcoin), _BTCPay Server_ generates a new address for that customer. More specifically, _BTCPay Server_ iterates on the _address_index_ tree to create a new address to display to the customer, as defined by BIP-44. If the customer decides to switch payment methods or abandon the transaction entirely, this Bitcoin address goes unused and will not be used for another customer right away. At a single moment in time, Gabriel's website may have a large volume of outstanding addresses for customers making purchases, some of which may go unused and eventually expire. Once these addresses expire, _BTCPay Server_ will go back to reuse these addresses to fill the gap in _address_index_, but it becomes clear how there can be gaps between the _address_index_ leaves of the hierarchical deterministic tree where the money is actually located. Let's say that Gabriel is interested in viewing his total amount of bitcoin earned on a watch-only wallet (one that allows you to view transaction history, but not spend funds) that is separate from BTCPay Server but also conforms to the BIP-44 standard. How should this separate wallet go about searching for funds in this vast hierarchical tree, and when should it stop looking? Most wallets will typically follow an iterative process that utilizes a predefined limit, known as the _gap limit_. If, while searching for used addresses, the wallet doesn't find used addresses in a row beyond this limit number, it will stop searching the address chain. The default gap limit is typically set to 20. This is detailed in [[bip-44]]https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki[BIP-44]. [TIP] ==== Gap limits explain the phenomenon whereby the importing of a wallet may show an incorrect or zero balance. The funds are not lost, but rather, the wallet importing function has not traversed enough leaves to fully detect funds. Many wallets allow this default gap limit to be changed, and Gabriel may need to increase this limit to allow his wallet to fully import his transaction history.