createFromUri now derives ML-DSA pairs from the mnemonic along a hardened BIP44
path rather than from a seed along a junction chain. Lattice keys have no public
derivability, so there is no soft junction to emulate and the chain's own
Pair::derive refuses for the same reason.
The path is m/44'/189189'/<account>'/0'/<0 for 87 | 1 for 65>'. Two things about
it are unusual and both are deliberate: the account index sits at the third level
rather than the last, and the trailing index carries the scheme rather than an
address index. It is what quantus-cli and the mobile wallet already derive, so
anything else produces addresses no other Quantus tool can find.
The ML-DSA branch sits before the existing seeding, not after, because that
seeding is the wrong one for us. mnemonicToMiniSecret is Substrate's variant and
the default reach in this file; using it here yields a perfectly well-formed key
for an account nobody owns. We need the 64-byte BIP39 seed and the HMAC-SHA512
chain keyed with "Dilithium seed", which is what the hdwallet crate does.
Accepted suri forms are nothing (account 0, matching quantus-cli's default),
//<n> for an account index, and //m/44'/… for a full path. Everything else
throws. That matters more than it looks: the syntax was built for curve
junctions, where /foo is soft and //foo hard over arbitrary bytes, and quietly
reinterpreting //Alice as something would hand back an address no other tool
derives and no seed phrase obviously recovers.
A raw hex seed is taken undederived — that is how the dev-genesis accounts are
defined — and combining one with a derivation path is refused rather than
guessed, since whether such a seed is the master or already derived is
unanswerable.
pair.derive() refuses with its own message. Not "not implemented" but not
possible: a child would have to come from this pair's key material, and ML-DSA
keys are not derivable from one another at all. The caller needs the mnemonic, so
the error says so rather than being generically unhelpful.
Verified against quantus-cli for both schemes from the public Substrate dev
phrase, plus index separation, explicit paths agreeing with indices, passphrase
sensitivity, and every refusal.
Refs quantus/common#4
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012uDUodEcRbBwNRi3UCmw8f
