H1: Add two-level BIP-32 derivation with 62-bit entropy for V3+ projects#912
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DavidGershony wants to merge 1 commit into
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H1: Add two-level BIP-32 derivation with 62-bit entropy for V3+ projects#912DavidGershony wants to merge 1 commit into
DavidGershony wants to merge 1 commit into
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Add DeriveProjectIndicesV2() that splits 62 bits of a SHA-256d hash into
two 31-bit indices, enabling a two-level hardened derivation path that
reduces collision probability from ~46k projects to ~2 billion.
Add BuildProjectSubPath() that returns the appropriate path component:
- V1/V2: single level '{upi}' (31-bit, backward compatible)
- V3+: two levels '{hi}/{lo}' (62-bit)
All derivation methods (DeriveInvestorKey, DeriveFounderRecoveryKey,
DeriveNostrPubKey, DeriveAngorKey, etc.) now have version-aware overloads
that default to V1 behavior for backward compatibility.
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Summary
Add two-level BIP-32 hardened derivation paths for V3+ projects, increasing path entropy from 31 bits (~46k collision threshold) to 62 bits (~2 billion collision threshold).
Problem
The current single-level derivation uses 31 bits of entropy from SHA-256d(founderKey), giving a Birthday-bound collision probability of ~46k projects before a 50% chance of path collision.
Solution
DeriveProjectIndicesV2(founderKey)that splits 62 bits into two 31-bit indices (each valid for BIP-32 hardened derivation, max 2^31-1)BuildProjectSubPath(founderKey, projectVersion)that returns:{upi}'(single level, backward compatible){hi}'/{lo}'(two levels, 62-bit entropy)DeriveAngorKeyalso supports V3+ with two-levelDerive(hi).Derive(lo)Version Gating
Uses
projectVersionparameter (defaults to 1). Callers pass the project's version when creating V3+ projects. Existing V1/V2 projects continue using the single-level path.Testing
All 154 shared tests pass.