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# BIP-44 derivation paths
Each coin uses [BIP-44](https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki) derivation path scheme. If the coin is UTXO-based the path should have all five parts, precisely as defined in [BIP-32](https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki). If it is account-based we follow Stellar's [SEP-0005](https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0005.md) - paths have only three parts `44'/c'/a'`. Unfortunately, lot of exceptions occur due to compatibility reasons.
Each coin uses [BIP-44] derivation path scheme. If the coin is UTXO-based the path
should have all five parts, precisely as defined in [BIP-32]. If it is account-based we
follow Stellar's [SEP-0005] - paths have only three parts `44'/c'/a'`. Unfortunately,
lot of exceptions occur due to compatibility reasons.
Keys are derived according to [SLIP-10], which is a superset of the BIP-32 derivation
algorithm, extended to work on other curves.
[bip-44]: https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki
[bip-32]: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki
[sep-0005]: https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0005.md
[slip-10]: https://github.com/satoshilabs/slips/blob/master/slip-0010.md
## List of used derivation paths
| coin | curve | getPublicKey | getAddress | sign tx | derivation | note |
|----------------|----------------|----------------|------------------|------------------|-----------------|--------------|
| Bitcoin | secp256k | 44'/c'/a' | 44'/c'/a'/y/i | 44'/c'/a'/y/i | BIP-32 | [1](#Bitcoin) |
| Ethereum | secp256k | 44'/60'/0' | 44'/60'/0'/0/i | 44'/60'/0'/0/i | BIP-32 | [2](#Ethereum)|
| Ripple | secp256k | - | 44'/144'/a'/0/0 | 44'/144'/a'/0/0 | BIP-32 | [3](#Ripple) |
| Cardano | ed25519 | 44'/1815'/a' | 44'/1815'/a'/{0,1}/i | 44'/1815'/a'/{0,1}/i | [Cardano's own](https://cardanolaunch.com/assets/Ed25519_BIP.pdf)<sup>[4](#Cardano)</sup> | |
| Stellar | ed25519 | - | 44'/148'/a' | 44'/148'/a' | SLIP-0010 | |
| Lisk | ed25519 | 44'/134'/a' | 44'/134'/a' | 44'/134'/a' | SLIP-0010 | |
| NEM | ed25519 | - | 44'/43'/a' | 44'/43'/a' | SLIP-0010 | [5](#NEM) |
| Monero | ed25519 | 44'/128'/a'<sup>[6](#Monero)</sup> | 44'/128'/a' | 44'/128'/a' | SLIP-0010 | |
| Tezos | ed25519<sup>[7](#Tezos)</sup> | 44'/1729'/a' | 44'/1729'/a' | 44'/1729'/a' | SLIP-0010 | |
| coin | curve | path | public node | note |
| -------- | -------- | ------------------ | ----------- | -------------- |
| Bitcoin | secp256k | `44'/c'/a'/y/i` | yes | [1](#Bitcoin) |
| Ethereum | secp256k | `44'/c'/0'/0/a` | yes | [2](#Ethereum) |
| Ripple | secp256k | `44'/144'/a'/0/0` | | [3](#Ripple) |
| Cardano | ed25519 | `44'/1815'/a'/y/i` | yes | [4](#Cardano) |
| Stellar | ed25519 | `44'/148'/a'` | | |
| Lisk | ed25519 | `44'/134'/a'` | | |
| NEM | ed25519 | `44'/43'/a'` | | [5](#NEM) |
| Monero | ed25519 | `44'/128'/a'` | | |
| Tezos | ed25519 | `44'/1729'/a'` | | [6](#Tezos) |
Paths that do not conform to this table are allowed, but user needs to confirm a warning on Trezor. For getPublicKey we do not check if the path is followed by other non-hardened items (anyone can derive those anyway). This is beneficial for Ethereum and its MEW compatibility, which sends `44'/60'/0'/0` for getPublicKey.
`c` stands for the [SLIP-44 id] of the currency, when multiple currencies are handled
by the same code. `a` is an account number, `y` is change address indicator (must be
0 or 1), and `i` is address index.
## Notes
[slip-44 id]: https://github.com/satoshilabs/slips/blob/master/slip-0044.md
1. <a name="Bitcoin"></a> For Bitcoin and its derivatives it is a little bit more complicated. `p` is decided based on the following table:
Paths that do not conform to this table are allowed, but user needs to confirm a warning
on Trezor.
| p | type | input script type |
|-----|--------------|--------------------|
| 44 | legacy | SPENDADDRESS |
| 48 | multisig | SPENDMULTISIG |
| 49 | p2sh segwit | SPENDP2SHWITNESS |
| 84 | native segwit | SPENDWITNESS |
### Public nodes
Other `p` are disallowed. `c` has to be equal to the coin's [slip44 id](https://github.com/satoshilabs/slips/blob/master/slip-0044.md) as for every coin. `y` needs to be 0 or 1.
Some currencies allow exporting a _public node_, which lets the client derive all
non-hardened paths below it. In that case, the conforming path is equal to the
hardened prefix.
2. <a name="Ethereum"></a> We believe this should be `44'/60'/a'`, because Ethereum is account-based, rather than UTXO-based. Unfortunately, lot of Ethereum tools (MEW, Metamask) do not use such scheme and set `a = 0` and then iterate the address index `i`. Therefore for compatibility reasons we use the same scheme: `44'/60'/0'/0/i` and only the `i` is being iterated.
I.e., for Bitcoin's path `44'/c'/a'/y/i`, the allowed public node path is `44'/c'/a'`.
3. <a name="Ripple"></a> Similar to Ethereum this should be `44'/144'/a'`. But for compatibility with other HW vendors we use `44'/144'/a'/0/0`.
Trezor does not check if the path is followed by other non-hardened items (anyone can
derive those anyway). This is beneficial for Ethereum and its MEW compatibility, which
sends `44'/60'/0'/0` for getPublicKey.
4. <a name="Cardano"></a> Which allows non-hardened derivation on ed25519.
### Notes
5. <a name="NEM"></a> NEM's path should be `44'/60'/a'` as per SEP-0005, but we allow `44'/60'/a'/0'/0'` as well for compatibility reasons with NanoWallet.
1. <a name="Bitcoin"></a> For Bitcoin and its derivatives it is a little bit more
complicated. `p` is decided based on the following table:
6. <a name="Monero"></a> Actually it is GetWatchKey for Monero.
| p | type | input script type |
| --- | --------------- | ----------------- |
| 44 | legacy | SPENDADDRESS |
| 48 | legacy multisig | SPENDMULTISIG |
| 49 | p2sh segwit | SPENDP2SHWITNESS |
| 84 | native segwit | SPENDWITNESS |
7. <a name="Tezos"></a> Tezos supports multiple curves, but Trezor currently supports ed25519 only.
Other `p` are disallowed.
2. <a name="Ethereum"></a> We believe this should be `44'/c'/a'`, because Ethereum is
account-based, rather than UTXO-based. Unfortunately, lot of Ethereum tools (MEW,
Metamask) do not use such scheme and set `a = 0` and then iterate the address index
`i`. Therefore for compatibility reasons we use the same scheme.
3. <a name="Ripple"></a> Similar to Ethereum this should be `44'/144'/a'`. But for
compatibility with other HW vendors we use `44'/144'/a'/0/0`.
4. <a name="Cardano"></a> Cardano has a [custom derivation] algorithm that allows
non-hardened derivation on ed25519.
[custom derivation]: https://cardanolaunch.com/assets/Ed25519_BIP.pdf
5. <a name="NEM"></a> NEM's path should be `44'/43'/a'` as per SEP-0005, but we allow
`44'/43'/a'/0'/0'` as well for compatibility reasons with NanoWallet.
6. <a name="Tezos"></a> Tezos supports multiple curves, but Trezor currently supports
ed25519 only.
Sign message paths are validated in the same way as the sign tx paths are.
## Allowed values
For GetPublicKey `a` needs in the interval of \[0, 20]. For GetAddress and signing the longer five-items paths need to have `a` also in range of \[0, 20] and `i` in \[0, 1000000]. If only three-items paths are used (Stellar and Lisk for example), `a` is allowed to be in \[0, 1000000] (because there is no address index `i`).
For UTXO-based currencies, account number `a` needs to be in the interval \[0, 20]
and address index `i` in the interval \[0, 1 000 000].
For account-based currencies (i.e., those that do not use address indexes), account
number `a` needs to be in the interval \[0, 1 000 000]