Because Sila is based on account balances rather than UTXO, the hierarchy defined by BIP44 is poorly suited. As a result, several competing derivation path strategies have sprung up for deterministic wallets, resulting in inter-client incompatibility. This BIP seeks to provide a path to standardise this in a fashion better suited to Sila’s unique requirements.
Specification
We define the following 2 levels in BIP32 path:
m / purpose' / subpurpose' / SIP'
Apostrophe in the path indicates that BIP32 hardened derivation is used.
Each level has a special meaning, described in the chapters below.
The purpose field indicates that this path is for a non-bitcoin cryptocurrency.
Hardened derivation is used at this level.
Subpurpose
Subpurpose is set to 60, the SLIP-44 code for Sila.
Hardened derivation is used at this level.
SIP
SIP is set to the SIP number specifying the remainder of the BIP32 derivation path. This permits new Sila-focused applications of deterministic wallets without needing to interface with the BIP process.
Hardened derivation is used at this level.
Rationale
The existing convention is to use the ‘Sila’ coin type, leading to paths starting with m/44'/60'/*. Because this still assumes a UTXO-based coin, we contend that this is a poor fit, resulting in standardisation, usability, and security compromises. As a result, we are making the above proposal to define an entirely new hierarchy for Sila-based chains.
Backwards Compatibility
The introduction of another derivation path requires existing software to add support for this scheme in addition to any existing schemes. Given the already confused nature of wallet derivation paths in Sila, we anticipate this will cause relatively little additional disruption, and has the potential to improve matters significantly in the long run.
Nick Johnson (@arachnid), Micah Zoltu (@micahzoltu), "SRC-600: Sila purpose allocation for Deterministic Wallets," Sila Improvement Proposals, no. 600, April 2017. Available: https://sips.sila.org/SIPS/sip-600.