mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-11-29 19:08:12 +00:00
53 lines
1.8 KiB
Markdown
53 lines
1.8 KiB
Markdown
|
# Purpose48 derivation scheme
|
||
|
|
|
||
|
|
Per [BIP-43], the first level of the derivation path is used as a "purpose". The purpose
|
||
|
|
number is usually selected to match the BIP number: e.g., BIP-49 uses purpose `49'`.
|
||
|
|
|
||
|
|
There is no officially proposed **BIP-48** standard. Despite that, a de-facto standard
|
||
|
|
for the purpose `48'` exists in the wild and is implemented by several HD wallets, most
|
||
|
|
notably [Electrum]. This standard was never before formally
|
||
|
|
specified, and this document aims to rectify the situation.
|
||
|
|
|
||
|
|
## Motivation
|
||
|
|
|
||
|
|
Purpose48 is intended for multisig scenarios. It allows using multiple script types from
|
||
|
|
a single logical account or root key, while keeping multisig keys separate from
|
||
|
|
single-sig keys.
|
||
|
|
|
||
|
|
## Specification
|
||
|
|
|
||
|
|
The following BIP-32 path levels are defined:
|
||
|
|
|
||
|
|
```
|
||
|
|
m / 48' / coin_type' / account' / script_type' / change / address_index
|
||
|
|
```
|
||
|
|
|
||
|
|
Meaning of all fields except `script_type` is defined in [BIP-44]
|
||
|
|
|
||
|
|
`script_type` can have the following values:
|
||
|
|
|
||
|
|
* `0`: raw [BIP-11] (p2ms) multisig
|
||
|
|
* `1`: p2sh-wrapped segwit multisig (p2wsh-p2sh)
|
||
|
|
* `2`: native segwit multisig (p2wsh)
|
||
|
|
|
||
|
|
The path derivation is hardened up to and including the `script_type` field.
|
||
|
|
|
||
|
|
## Trezor implementation
|
||
|
|
|
||
|
|
`script_type` value `0` corresponds to `SPENDMULTISIG`/`PAYTOMULTISIG`.
|
||
|
|
|
||
|
|
Value `1` corresponds to `SPENDP2SHWITNESS`/`PAYTOP2SHWITNESS`.
|
||
|
|
|
||
|
|
Value `2` corresponds to `SPENDWITNESS`/`PAYTOWITNESS`.
|
||
|
|
|
||
|
|
## References
|
||
|
|
|
||
|
|
Electrum implementation: https://github.com/spesmilo/electrum/blob/9931df9f254e49eb929723be62af61971b3032c8/electrum/keystore.py#L862-L889
|
||
|
|
|
||
|
|
Trezor implementation: TBD
|
||
|
|
|
||
|
|
[Electrum]: https://electrum.org/
|
||
|
|
[BIP-11]: https://github.com/bitcoin/bips/blob/master/bip-0011.mediawiki
|
||
|
|
[BIP-43]: https://github.com/bitcoin/bips/blob/master/bip-0043.mediawiki
|
||
|
|
[BIP-44]: https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki
|