Derivation Path

[Robco87]

Is is possible to modify the derivation path and if so would that be done in BRBIP32sequence.c?

[EBGToo]

You are looking to generate keys for non-bitcoin currencies?

For our latest 'Ethereum' release we define the following:

extern BRKey
derivePrivateKeyFromSeed (UInt512 seed, uint32_t index) {
    BRKey privateKey;
    
    // The BIP32 privateKey for m/44'/60'/0'/0/index
    BRBIP32PrivKeyPath(&privateKey, &seed, sizeof(UInt512), 5,
                       44 | BIP32_HARD,          // purpose  : BIP-44
                       60 | BIP32_HARD,          // coin_type: Ethereum
                       0  | BIP32_HARD,          // account  : <n/a>
                       0,                        // change   : not change
                       index);                   // index    :
    
    privateKey.compressed = 0;
    
    return privateKey;
}

You can define an analogous function for something besides 'Ethereum'. Or call BRBIP32PrivKeyPath() with the arguments you need.

[Robco87]

It would be for bitcoin.
I have a use case that needs to support some legacy addresses that were created using Bip49.
Would using the above method be a simple as updated to:
BRBIP32PrivKeyPath(&privateKey, &seed, sizeof(UInt512), 5,
49 | BIP32_HARD,
0 | BIP32_HARD, //1 for testnet
0 | BIP32_HARD,
0,
index);

[EBGToo]

Yes, it may very well be. Certainly worth a try.

[Robco87]

This could work for the private key path, but when restoring wallets its setting up the master public key. Do I also need to modify the path when a master public key is generated?