rob thijssen
e6ff57a334
Three things the tier-1 case matrix needed (quantus/extension#7). **Storage keys and values (#4).** `storage_target` resolves a pallet and item to `twox128(prefix) ‖ twox128(item)` plus each map key hashed by the hasher the entry declares, and reports the value type and the entry's default. `decode_storage_value` reads the result. Nothing here knows that `System::Account` is a `Blake2_128Concat` map over an `AccountId32`; the hashers, both types and the default all come out of the metadata. The `Default` versus `Optional` distinction is carried deliberately. A `Default` entry that the node returns nothing for means the declared default — an account nobody has funded reads as a zero balance — where an `Optional` one means nothing. A wallet that conflated them would report a failure for an account that simply has no money in it. **A call nests inside a call.** A multi-field variant with named fields only accepted a positional array, so `Utility.batch_all` — whose `Vec<RuntimeCall>` holds calls spelled exactly like top-level ones — could not be encoded at all. It now takes the same object form at any depth. **Every integer renders as a decimal string**, whatever its width, and that is now stated rather than incidental. A u128 balance does not survive a JSON number (12 decimal places puts ordinary amounts past 2^53) and `scale_value` widens every unsigned integer to u128, so the width is not available to switch on. Emitting a number when it happens to fit and a string when it does not would make a consumer handle both shapes for the same field depending on the value. All of it proven against Heisenberg: an ML-DSA-65 account funded by a `batch_all` whose payload crossed the 256-byte BLAKE2b threshold, then signing and being included itself. Closes #4. Refs #3 Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_012uDUodEcRbBwNRi3UCmw8f
@quantus/codec
Metadata-driven SCALE encode and decode for the Quantus chain, compiled to WASM.
Nothing in this package names a pallet, a call, a signed extension or a signature
scheme. Everything is read from the metadata the node produced by running
Metadata_metadata against the runtime WASM in a given block's state, which
makes the runtime the oracle rather than this package's author.
Why not @polkadot/api
Three reasons, in increasing order of importance — the evidence is on quantus/api#1.
@polkadot/typesrefuses fixed arrays longer than 2048 bytes. ML-DSA signatures are[u8;5261]and[u8;7219], so every Quantus extrinsic trips it.api.rpc.chain.getBlockthrows on every block of this chain, at the timestamp inherent. The extrinsic preamble byte's top two bits are a type tag (0b00bare,0b10signed,0b01general) and the low six are the version; Quantus emits0x84— signed, v4 — and0x05— bare, v5 — in the same block while the metadata declares version 4. polkadot-js reads that byte as a version.- It guesses that signed extensions it does not recognise contribute nothing
to the signed payload, logging
Unknown signed extensions … treating them as no-effect.
The third is why this package exists rather than a patch. The guess is correct
only while every unrecognised extension happens to be zero-sized. This chain's
encoding has already changed between runtimes — transactionVersion has gone
2 → 3 → 6 across four upgrades, each an extrinsic-format change — and when the
guess stops being correct the wallet keeps signing. Those signatures are
cryptographically valid, over a payload missing bytes the runtime put there, and
the chain reports them as BadProof, which is also what it reports for a wrong
key. Silent, remote, and indistinguishable from the one thing it is not.
Here the registry decides. An extension whose declared type encodes to nothing contributes nothing; anything else must be supplied by the caller or no payload is produced at all.
Use
import { Runtime } from '@quantus/codec';
const runtime = Runtime.fromMetadata(await fetchMetadata()); // state_getMetadata
const call = runtime.encodeCall('Balances', 'transfer_keep_alive', {
dest: { Id: '0x…' },
value: '1000000000'
});
const values = runtime.standardExtensions({
blockHash: genesisHash, // immortal era
genesisHash,
nonce,
specVersion,
transactionVersion
});
const payload = runtime.signerPayload(call, values);
// sign `payload` with @quantus/crypto under the QUANTUS_EXTRINSIC context,
// hashing it first with BLAKE2b-256 if it is longer than 256 bytes
const extrinsic = runtime.encodeExtrinsic(
{ Id: accountId },
signature,
runtime.encodeExtra(values),
call
);
standardExtensions fills in the extensions Substrate itself defines. Anything
else this runtime declares as non-empty is refused by name — see above for why
that is the desired behaviour rather than a limitation.
Build
./scripts/build-quantus.sh quantus-codec
Same constraints as @quantus/crypto: a modern toolchain (separate from
wasm-crypto's 2022 nightly), initSync over base64+zlib for the MV3 CSP,
wasm-bindgen's own glue rather than @polkadot/wasm-bridge, and binaryen 123
— version 105 silently corrupts the output. See
quantus/wasm#1 and
#3.