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96 lines
4.5 KiB
Markdown
96 lines
4.5 KiB
Markdown
# BIP-44 derivation paths
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Each coin uses [BIP-44] derivation path scheme. If the coin is UTXO-based the path
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should have all five parts, precisely as defined in [BIP-32]. If it is account-based we
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follow Stellar's [SEP-0005] - paths have only three parts `44'/c'/a'`. Unfortunately,
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lot of exceptions occur due to compatibility reasons.
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Keys are derived according to [SLIP-10], which is a superset of the BIP-32 derivation
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algorithm, extended to work on other curves.
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[bip-44]: https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki
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[bip-32]: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki
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[sep-0005]: https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0005.md
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[slip-10]: https://github.com/satoshilabs/slips/blob/master/slip-0010.md
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## List of used derivation paths
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| coin | curve | path | public node | note |
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| -------- | --------- | ------------------ | ----------- | -------------- |
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| Bitcoin | secp256k1 | `44'/c'/a'/y/i` | yes | [1](#Bitcoin) |
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| Ethereum | secp256k1 | `44'/c'/0'/0/a` | yes | [2](#Ethereum) |
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| Ripple | secp256k1 | `44'/144'/a'/0/0` | | [3](#Ripple) |
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| EOS | secp256k1 | `44'/194'/a'/0/0` | | [3](#Ripple) |
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| Binance | secp256k1 | `44'/714'/a'/0/0` | | [3](#Ripple) |
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| Tron | secp256k1 | TODO | | TODO |
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| Ontology | nist256p1 | TODO | | TODO |
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| Cardano | ed25519 | `44'/1815'/a'/y/i` | yes | [4](#Cardano) |
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| Stellar | ed25519 | `44'/148'/a'` | | |
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| NEM | ed25519 | `44'/43'/a'` | | [5](#NEM) |
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| Monero | ed25519 | `44'/128'/a'` | | |
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| Tezos | ed25519 | `44'/1729'/a'` | | [6](#Tezos) |
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`c` stands for the [SLIP-44 id] of the currency, when multiple currencies are handled
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by the same code. `a` is an account number, `y` is change address indicator (must be
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0 or 1), and `i` is address index.
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[slip-44 id]: https://github.com/satoshilabs/slips/blob/master/slip-0044.md
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Paths that do not conform to this table are allowed, but user needs to confirm a warning
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on Trezor.
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### Public nodes
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Some currencies allow exporting a _public node_, which lets the client derive all
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non-hardened paths below it. In that case, the conforming path is equal to the
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hardened prefix.
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I.e., for Bitcoin's path `44'/c'/a'/y/i`, the allowed public node path is `44'/c'/a'`.
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Trezor does not check if the path is followed by other non-hardened items (anyone can
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derive those anyway). This is beneficial for Ethereum and its MEW compatibility, which
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sends `44'/60'/0'/0` for getPublicKey.
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### Notes
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1. <a name="Bitcoin"></a> For Bitcoin and its derivatives it is a little bit more
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complicated. `p` is decided based on the following table:
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| p | type | input script type |
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| --- | --------------- | ----------------- |
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| 44 | legacy | SPENDADDRESS |
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| 48 | legacy multisig | SPENDMULTISIG |
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| 49 | p2sh segwit | SPENDP2SHWITNESS |
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| 84 | native segwit | SPENDWITNESS |
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Other `p` are disallowed.
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2. <a name="Ethereum"></a> We believe this should be `44'/c'/a'`, because Ethereum is
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account-based, rather than UTXO-based. Unfortunately, lot of Ethereum tools (MEW,
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Metamask) do not use such scheme and set `a = 0` and then iterate the address index
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`i`. Therefore for compatibility reasons we use the same scheme.
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3. <a name="Ripple"></a> Similar to Ethereum this should be `44'/c'/a'`. But for
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compatibility with other HW vendors we use `44'/c'/a'/0/0`.
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4. <a name="Cardano"></a> Cardano has a [custom derivation] algorithm that allows
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non-hardened derivation on ed25519.
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[custom derivation]: https://cardanolaunch.com/assets/Ed25519_BIP.pdf
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5. <a name="NEM"></a> NEM's path should be `44'/43'/a'` as per SEP-0005, but we allow
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`44'/43'/a'/0'/0'` as well for compatibility reasons with NanoWallet.
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6. <a name="Tezos"></a> Tezos supports multiple curves, but Trezor currently supports
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ed25519 only.
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Sign message paths are validated in the same way as the sign tx paths are.
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## Allowed values
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For UTXO-based currencies, account number `a` needs to be in the interval \[0, 20]
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and address index `i` in the interval \[0, 1 000 000].
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For account-based currencies (i.e., those that do not use address indexes), account
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number `a` needs to be in the interval \[0, 1 000 000]
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