Native backend

NativeBackend (src/native-backend.ts) is a Node-only thin wrapper that shells out to the compiled ecdsa-spartan2 Rust CLI. Use it when:

• you want to run prepare setup / show setup (the WASM bridge cannot do setup);
• you have proving keys too large for browser memory (≥ 258 MB for the 1k variant);
• you need parity with the CI / benchmark pipeline that lives under wallet-unit-poc/ecdsa-spartan2/.

It is not loaded by OpenAC.init and adds no dependencies for browser bundles — import the class directly:

import { NativeBackend } from "openac-sdk";

const native = new NativeBackend({ workDir: "wallet-unit-poc/ecdsa-spartan2" });

If binaryPath or workDir are omitted, NativeBackend searches relative paths from the SDK install location and process.cwd(). It throws SetupError("KEYS_NOT_FOUND") when neither resolves.

Configuration

Field	Type	Default	Description
binaryPath	string	First match of target/release/ecdsa-spartan2 near the SDK or in cwd().	Absolute path to the compiled CLI binary.
workDir	string	First directory containing Cargo.toml near the SDK or in cwd().	Directory the CLI runs in (keys, artifacts and inputs are resolved relative to it).
inputDir	string	${workDir}/../circom/inputs	Where the input JSONs live (jwt/<size>/default.json, show/default.json).
env	Record<string, string>	RUST_LOG=info plus auto-detected DYLD_LIBRARY_PATH for the witnesscalc dylib.	Extra env vars merged into the child process.

Lifecycle

const native = new NativeBackend();

await native.setup("wallet-unit-poc/circom/inputs/jwt/1k/default.json");
await native.proveAll(
  "wallet-unit-poc/circom/inputs/jwt/1k/default.json",
  "wallet-unit-poc/circom/inputs/show/default.json",
);
const { valid } = await native.verifyPrepare();

Method	CLI command run	Default timeout	Notes
setupPrepare(inputPath?)	prepare setup	20 min	Writes keys/prepare_*.key.
setupShow(inputPath?)	show setup	10 min	Writes keys/show_*.key.
setup(inputPath?)	both	30 min	Convenience for one-shot setup.
provePrepare(inputPath?)	prepare prove	5 min	Reads prepare_proving.key, writes prepare_proof.bin, prepare_instance.bin, prepare_witness.bin.
proveShow(inputPath?)	show prove	2 min	Reads show_proving.key, writes show_* artifacts.
generateSharedBlinds()	generate_shared_blinds	10 min	Writes keys/shared_blinds.bin.
reblindPrepare() / reblindShow()	prepare reblind / show reblind	5 min / 2 min	Applies the shared blinds.
verifyPrepare() / verifyShow()	prepare verify / show verify	10 min	Returns { valid, output } based on a substring check for "Verification successful".
runBenchmark(inputPath?)	benchmark	30 min	Captures stdout/stderr for the benchmark harness.
proveAll(jwtInputPath?, showInputPath?)	composite of the above	inherited	generate_shared_blinds → prove prepare → reblind prepare → prove show → reblind show.

Artifacts

NativeBackend.loadKeys() reads the four *.key files into a KeySet compatible with OpenAC.precompute / OpenAC.present. loadProofs() returns the proof, instance, witness, and shared-blind bytes — useful for transporting Rust-generated artifacts into the WASM verifier.

saveArtifact(filename, data) / loadArtifact(filename) are escape hatches for custom file layouts; they read and write under ${workDir}/keys/.

The keysExist and proofsExist getters do a non-throwing existence check before attempting a CLI command.

Errors

Failure	Thrown
Binary or workDir not found at construction time	SetupError("KEYS_NOT_FOUND")
Non-zero exit from any CLI invocation	ProofError("PROOF_GENERATION_FAILED") with cause set to the underlying execFile error.

The output field on verifyPrepare() / verifyShow() returns the combined stdout+stderr; the CLI prints Verification successful on success, which is the substring NativeBackend looks for.