Solution: LP-0005 — Private Balance Attestation

[edenbd1]

Implementation of LP-0005: a reusable private token balance attestation primitive for the Logos Execution Zone.

• Repository: https://github.com/edenbd1/lp-0005-private-token-balance-attestation (MIT OR Apache-2.0)
• Narrated demo video: https://youtu.be/Ta18-p3sz3M
• Solution write-up: solutions/LP-0005.md

✅ Deployed live on the public Logos Execution Zone testnet — with a confirmed on-chain gated_check

• Sequencer: https://testnet.lez.logos.co
• Block explorer: https://explorer.testnet.lez.logos.co
• Signer (anchorer): CbgR6tj5kWx5oziiFptM7jMvrQeYY3Mzaao6ciuhSr2r

Public on-chain evidence — every tx independently verifiable via getTransaction JSON-RPC or by clicking the explorer link:

#	Action	Tx hash
1	wallet deploy-program — attestation circuit (Risc0 guest proving balance ≥ N, ImageID dbc40b94…6a9d4d)	4593060b…3db989d
2	wallet deploy-program — verifier program v2 (SPEL, deep gate via ChainedCall, ImageID 7715f791…d8a1db429)	2bf10138…23723a9
3	wallet deploy-program — verifier program v3 (SPEL, shallow gate, ImageID b32c6662…df85952a)	a0ec45bb…d341c5ca
4	✅ spel gated_check CONFIRMED on chain — real Risc0 receipt + real ECDSA-signed challenge → v3 verifier accepts	262bbe95…6babfd5e

Full deployment record (with reproduction commands) in docs/DEPLOYMENT.md.

Summary

A presenter holding a shielded LEZ token account can prove balance ≥ N without revealing the account's npk, exact balance, or identity. Two verification paths:

• On-chain — SPEL #[lez_program] (crates/verifier-program-spel/methods/guest-shallow/src/bin/attestation_verifier_shallow.rs), validates context binding + threshold floor + ECDSA presenter signature. Confirmed end-to-end against the v3 verifier above.
• Off-chain — Rust library (crates/verifier-offchain/) that runs the same check_gate rules locally against a Risc0 receipt delivered over any transport (in-memory backend committed; qt_bridge feature gate for the production Logos Delivery binding).

Highlights vs the spec

• Verifiable public-testnet deployment — the 4 tx hashes above, all live on https://testnet.lez.logos.co. Anyone can getTransaction them or open the explorer link.
• End-to-end on-chain gated_check confirmed — not just a deployed program, but a real ECDSA-signed gate call that the verifier accepted and that landed in a block.
• Real Risc0 proofs — scripts/demo.sh exports RISC0_DEV_MODE=0 as its first non-comment line; the demo prints the banner as its first non-blank output. Composite receipt 300,863 bytes in ~6.5 s; Groth16-wrapped receipt 1,479 bytes (203× smaller) in ~150 s via attest prove --groth16 for Logos Delivery payload-cap compatibility.
• Four reusable crates published on crates.io — attestation-core, attestation-verifier-program, attestation-sequencer-client, attestation-delivery-transport. External builders can cargo add directly.
• Basecamp .lgx published — app/lp-0005-attestation.lgx 2.1 MB, lgx verify ✅, SHA-256 193a903a…94c89770.
• Four reference integrations under integrations/ — governance-gate, chat-gate, premium-features, and nostr-auth-gate (NIP-42 relay AUTH starter for the outside-party port).
• 57 tests passing across the workspace (cargo test --workspace --release), CI green on main.
• 30-second reproducible demo — scripts/demo.sh runs the full pipeline against the public testnet from a clean clone, requires only curl, python3, jq, and cargo.

Per-criterion compliance map

See docs/criteria-checklist.md for the row-by-row mapping from every line of the prize text to the code, test, or transaction hash that satisfies it.

Architecture

LEZ verifier as a SPEL program (justified vs zone-SDK in ADR-001): a single gated_check instruction takes the flattened journal + ECDSA challenge response + caller-pinned context/threshold, runs the host-side gate, and (in the deep variant) declares a ChainedCall so the LEZ PPE pipeline composes the inner Risc0 receipt via env::verify. Three-piece structure (portable kernel + deep guest + shallow guest) covers both the architecturally-ideal path and the confirmable-today path. Decision write-up: ADR-002.

[github-actions]

✅ Validation passed

A reviewer will assess against the prize criteria.
ℹ️ Solution submission for LP-0005.
ℹ️ Checking repo: https://github.com/edenbd1/lp-0005-private-token-balance-attestation

---

Automated check. See solution template and TERMS.