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256 lines
6.2 KiB
Plaintext
<pre>
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BIP: 48
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Layer: Applications
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Title: Multi-Script Hierarchy for Multi-Sig Wallets
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Author: Fontaine <dentondevelopment@protonmail.com>
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Comments-Summary: No comments
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Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0048
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Status: Final
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Type: Standards Track
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Created: 2020-12-16
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License: MIT
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</pre>
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==Abstract==
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This BIP defines a logical hierarchy for deterministic multi-sig wallets based on an algorithm
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described in BIP-0067 (BIP67 from now on), BIP-0032 (BIP32 from now on), purpose scheme described in
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BIP-0043 (BIP43 from now on), and multi-account hierarchy described in
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BIP-0044 (BIP44 from now on).
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This BIP is a particular application of BIP43.
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==Copyright==
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This BIP falls under the MIT License.
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==Motivation==
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The motivation of this BIP is to define the existing industry wide practice of utilizing m/48'
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derivation paths in hierarchical deterministic multi-sig wallets so that other developers may
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benefit from a standard. This BIP allows for future script types to easily be appended to the
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specification so that a new BIP is not required for every future script type.
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The hierarchy proposed in this paper is quite comprehensive. It allows the handling of
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multiple accounts, external and internal chains per account, multiple script types and
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millions of addresses per chain.
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This paper was inspired from BIP44.
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==Backwards compatibility==
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Currently a number of wallets utilize the <code>m/48'</code> derivation scheme for HD multi-sig accounts.
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This BIP is intended to maintain the *existing* real world use of the <code>m/48'</code> derivation.
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No breaking changes are made so as to avoid "loss of funds" to existing users.
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Wallets which currently support the <code>m/48'</code> derivation will not need to make any changes
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to comply with this BIP.
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==Specification==
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===Key sorting===
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Any wallet that supports BIP48 inherently supports deterministic key sorting as per BIP67 so that all possible
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multi-signature addresses/scripts are derived from deterministically sorted public keys.
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===Path levels===
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We define the following 6 levels in BIP32 path:
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<pre>
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m / purpose' / coin_type' / account' / script_type' / change / address_index
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</pre>
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<code>h</code> or <code>'</code> in the path indicates that BIP32 hardened derivation is used.
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Each level has a special meaning, described in the chapters below.
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===Purpose===
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Purpose is a constant set to 48' following the BIP43 recommendation.
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It indicates that the subtree of this node is used according to this specification.
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Hardened derivation is used at this level.
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===Coin type===
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One master node (seed) can be used for multiple Bitcoin networks.
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Sharing the same space for various networks has some disadvantages.
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Avoiding reusing addresses across networks and improving privacy issues.
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Coin type <code>0</code> for mainnet and <code>1</code> for testnet.
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Hardened derivation is used at this level.
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===Account===
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This level splits the key space into independent user identities, following the BIP44 pattern,
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so the wallet never mixes the coins across different accounts.
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Users can use these accounts to organize the funds in the same
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fashion as bank accounts; for donation purposes (where all
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addresses are considered public), for saving purposes,
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for common expenses etc.
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Accounts are numbered from index 0 in sequentially increasing manner.
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This number is used as child index in BIP32 derivation.
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Hardened derivation is used at this level.
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===Script===
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This level splits the key space into two separate <code>script_type</code>(s). To provide
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forward compatibility for future script types this specification can be easily extended.
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Currently the only script types covered by this BIP are Native Segwit (p2wsh) and
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Nested Segwit (p2sh-p2wsh).
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The following path represents Nested Segwit (p2sh-p2wsh) mainnet, account 0:
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<code>1'</code>: Nested Segwit (p2sh-p2wsh) <code>m/48'/0'/0'/1'</code></br>
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The following path represents Native Segwit (p2wsh) mainnet, account 0:
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<code>2'</code>: Native Segwit (p2wsh) <code>m/48'/0'/0'/2'</code></br>
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The recommended default for wallets is pay to witness script hash <code>m/48'/0'/0'/2'</code>.
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===Change===
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Constant 0 is used for external chain and constant 1 for internal chain (also
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known as change addresses). External chain is used for addresses that are meant
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to be visible outside of the wallet (e.g. for receiving payments). Internal
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chain is used for addresses which are not meant to be visible outside of the
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wallet and is used for return transaction change.
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Public derivation is used at this level.
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===Index===
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Addresses are numbered from index 0 in sequentially increasing manner.
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This number is used as child index in BIP32 derivation.
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Public derivation is used at this level.
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==Examples==
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{|
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|network
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|account
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|script
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|chain
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|address
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|path
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|-
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|mainnet
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|first
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|p2sh-p2wsh
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|external
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|first
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|m / 48' / 0' / 0' / 1' / 0 / 0
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|-
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|mainnet
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|first
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|p2wsh
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|external
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|first
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|m / 48' / 0' / 0' / 2' / 0 / 0
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|-
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|mainnet
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|first
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|p2wsh
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|external
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|second
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|m / 48' / 0' / 0' / 2' / 0 / 1
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|-
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|mainnet
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|first
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|p2wsh
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|change
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|first
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|m / 48' / 0' / 0' / 2' / 1 / 0
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|-
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|mainnet
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|first
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|p2wsh
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|change
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|second
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|m / 48' / 0' / 0' / 2' / 1 / 1
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|-
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|mainnet
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|second
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|p2wsh
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|external
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|first
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|m / 48' / 0' / 1' / 2' / 0 / 0
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|-
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|mainnet
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|second
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|p2wsh
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|external
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|second
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|m / 48' / 0' / 1' / 2' / 0 / 1
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|-
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|testnet
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|first
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|p2sh-p2wsh
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|external
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|first
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|m / 48' / 1' / 0' / 1' / 0 / 0
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|-
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|testnet
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|first
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|p2wsh
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|external
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|second
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|m / 48' / 1' / 0' / 2' / 0 / 1
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|-
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|testnet
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|first
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|p2wsh
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|change
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|first
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|m / 48' / 1' / 0' / 2' / 1 / 0
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|-
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|testnet
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|first
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|p2wsh
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|change
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|second
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|m / 48' / 1' / 0' / 2' / 1 / 1
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|-
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|testnet
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|second
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|p2wsh
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|external
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|first
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|m / 48' / 1' / 1' / 2' / 0 / 0
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|-
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|testnet
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|second
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|p2wsh
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|external
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|second
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|m / 48' / 1' / 1' / 2' / 0 / 1
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|-
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|testnet
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|second
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|p2wsh
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|change
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|first
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|m / 48' / 1' / 1' / 2' / 1 / 0
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|-
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|testnet
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|second
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|p2wsh
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|change
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|second
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|m / 48' / 1' / 1' / 2' / 1 / 1
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|}
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==Reference==
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* [[bip-0067.mediawiki|BIP67 - Deterministic Pay-to-script-hash multi-signature addresses through public key sorting]]
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* [[bip-0032.mediawiki|BIP32 - Hierarchical Deterministic Wallets]]
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* [[bip-0043.mediawiki|BIP43 - Purpose Field for Deterministic Wallets]]
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* [[bip-0044.mediawiki|BIP44 - Multi-Account Hierarchy for Deterministic Wallets]]
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