# BIP-44 derivation paths
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 | 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) |
| EOS | secp256k | `44'/194'/a'/0/0` | | [3](#Ripple) |
| Tron | secp256k | TODO | | TODO |
| Ontology | nist256p1 | TODO | | TODO |
| 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) |
`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.
[slip-44 id]: https://github.com/satoshilabs/slips/blob/master/slip-0044.md
Paths that do not conform to this table are allowed, but user needs to confirm a warning
on Trezor.
### Public nodes
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.
I.e., for Bitcoin's path `44'/c'/a'/y/i`, the allowed public node path is `44'/c'/a'`.
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.
### Notes
1. For Bitcoin and its derivatives it is a little bit more
complicated. `p` is decided based on the following table:
| p | type | input script type |
| --- | --------------- | ----------------- |
| 44 | legacy | SPENDADDRESS |
| 48 | legacy multisig | SPENDMULTISIG |
| 49 | p2sh segwit | SPENDP2SHWITNESS |
| 84 | native segwit | SPENDWITNESS |
Other `p` are disallowed.
2. 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. Similar to Ethereum this should be `44'/c'/a'`. But for
compatibility with other HW vendors we use `44'/c'/a'/0/0`.
4. Cardano has a [custom derivation] algorithm that allows
non-hardened derivation on ed25519.
[custom derivation]: https://cardanolaunch.com/assets/Ed25519_BIP.pdf
5. 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. 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 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]